LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA 


PROF,  WJB.  RISING 

Class 


ELEMENTS 


OF 


CHEMISTRY, 


IJf    THK 


<>RIH:K   or   TIM:    LECTURES   GIVEN 


YALE    COLLEGE. 


BY  liK  \JAMIK  SIL.LJMAN, 

PROCESSOR  or  «:HEMIS TRY,  PHARMACY,  MINERALOGY  AND  GKOLOOT. 


IN  TWO  VOLUMES, 


NEW  HAVEN: 

KD  AND  PUBLISHED  BY  UEZEKIAH  HOWE. 


DISTRICT  OF  CONNECTICUT,  ss. 

*********       BE  IT  REMEMBERED,  That  on  the  eighteenth  day  of  February  in 

*  L.  S.  !  tne  nfty  fourth  year  of  the  Independence  of  the  United  States  of  Amer- 

*  ica,  BENJAMIN  SILLIMAN,  of  the  said  District,  hath  deposited  in  this 

*********  Office  the  title  of  a  Book,  the  right  whereof  he  claims  as  Author  in  the 

words  following,  to  wit : 

"  Elements  of  Chemistry,  in  the  order  of  the  lectures  given  in  Yale  College.  By 
Benjamin  Silliman,  Professor  of  Chemistry,  Pharmacy,  Mineralogy  and  Geology. 
In  two  volumes." 

In  conformity  to  the  Act  of  Congress  of  the  United  States,  entitled,  "  An  Act  for 
the  encouragement  of  learning,  by  securing  the  copies  of  Maps,  Charts,  and  Books, 
to  the  authors  and  proprietors  of  such  copies,  during  the  times  therein  mentioned." 
And  also  to  the  Act,  entitled,  "An  Act  supplementary  to  an  Act,  entitled,  'An  Act 
for  the  encouragement  of  learning,  by  securing  the  copies  of  Maps,  Charts,  and 
Books,  to  the  Authors  and  Proprietors  of  such  copies  during  the  times  therein  men- 
tioned,' and  extending  the  benefits  thereof  to  the  arts  of  designing,  engraving,  and 
etching  historical  and  other  prints." 

CHARLES  A.  INGERSOLL, 

Clerk  of  the  District  of  Connecticut. 
A  true  copy  of  Record,  examined  and  sealed  by  me, 

CHARLES  A.  INGERSOLL, 

Clerk  of  the  District  of  Connecticut, 


PREFACE. 


THE  object  of  this  work  is  to  present  the  science  of  Chemistry  in 
the  most  intelligible  form,  to  those  who  are  learning  its  elements ; 
and  for  the  convenience  of  the  classes  in  Yale  College,  the  topics 
are  arranged  in  the  order  in  which  they  are  now  discussed,  in  the 
lectures  given  in  that  Institution.  As  the  Medical  Class  constitutes  a 
part  of  the  audience,  the  most  important  pharmaceutical  prepara- 
tions, and  leading  uses  of  such  substances  as  belong  both  to  the  Ma- 
teria  Medica,  and  to  Chemistry,  are  briefly  mentioned  ;  and  in  gen- 
eral, throughout  the  work,  practical  facts  are  interwoven  with  scien- 
tific principles.  The  attempt  has  been  made,  to  unite  copiousness 
with  condensation  ;  perspicuity  with  brevity  ;  and  a  lucid  order,  and 
due  connexion  of  subordinate  parts,  with  a  general  unity  of  design. 

By  numerals*  and  letters,  the  topics  have  been  digested  under 
appropriate  heads ;  and  by  the  use  of  large  and  small  capitals,  and 
italics,  the  writer's  impression,  as  to  the  relative  importance  of  the 
leading  facts  and  propositions,  has  been  indicated. 

It  is  supposed  that  these  mechanical  helps,  not  novel  indeed,  but 
in  this  work,  more  extensively  employed  than  usual,  may  facilitate 
the  progress  of  the  student,  by  enabling  him  to  take,  at  pleasure,  a 
more  general,  a  more  particular,  or  a  detailed  review  ;  and  the  same 
facility  is,  of  course,  presented  to  the  instructor. 

Exact  accounts  of  processes  and  manipulations  have  been  given ; 
and  Dr.  Hare,  having  kindly  permitted  the  introduction  of  the  cuts,f 
from  his  Compendium,  his  own  language,  sometimes  abridged,  has 
been  generally  employed  in  the  descriptions  of  his  figures.  The  val- 
uable illustrations,  thus  derived  from  his  liberality,  render  it  unne- 
cessary to  apologize  for  the  frequent  use  of  his  name. 


*  Adopted,  to  some  extent,  by  Dr.  F.  Bache,  in  his  System  of  Chemistry  for  Med- 
ical Students,  and  more  fully  by  Dr.  Henry. 
t  The  more  complex  figures  have  been  omitted. 

237474 


IV  PREFACE. 

The  materials  of  this  work  have  been  gradually  accumulating  since 
1802.  They  have  been  drawn  from  Scientific  Journals,  from  the 
Transactions  of  Learned  Societies,  and  from  the  principal  writers  who 
have  flourished  since  the  middle  of  the  last  century — the  Augustan 
age  of  Chemistry.  From  works  of  an  earlier  date,  light  has  been  oc- 
casionally derived,  as  well  as  from  notes  and  recollections  of  the  in- 
structions of  the  distinguished  teachers,  to  whom  the  author  was 
formerly  so  happy  as  to  listen.  In  this  view,  he  takes  particular 
satisfaction  in  naming  the  late  Dr.  Murray,  of  Edinburgh,  and  Prof. 
Thomas  C.  Hope,  still  a  distinguished  ornament  of  the  University  in 
the  same  city. 

Various  notices,  derived  from  the  author's  own  experience,  and 
from  his  personal  communications  with  others,  are  introduced,  with 
occasional  figures,  for  illustration  ;  and  in  the  notes,  many  miscella- 
neous facts  are  preserved. 

In  the  immediate  preparation  of  this  work  for  the  press,  the  origi- 
nal memoirs  of  authors  and  discoverers  have  been  often  consulted, 
and  the  abstract  has  been  frequently  drawn  from  them,  rather  than  from 
the  elementary  books  ;  but  the  analyses  contained  in  the  latter  have 
not  unfrequently  been  adopted ;  sometimes  even  after  a  careful  ex- 
amination of  the  original,  and  for  this  reason,  among  others,  that  the 
statements  contained  in  them  could  be  often,  without  injury,  still 
farther  abridged.  In  such  cases,  several  eminent  elementary  writers 
have  been  diligently  compared,  on  the  same  subject  ;  and  thus 
omissions  have  been  supplied,  and  obscurity  has  been  removed,  either 
by  the  comparison,  or  by  resorting  to  the  first  record. 

References  to  the  original  memoirs  have  always  been  preserved, 
where  such  memoirs  were  attainable  ;  and  when  the  books  contain- 
ing them  were  not  at  hand,  the  citations  have  been  copied  from  the 
latest  systematical  writers.  Credit  has  also,  in  most  instances,  been 
given  to  elementary  writers,  for  materials  drawn  from  their  pages ; 
but  for  brevity,  and  especially  where  the  facts  are  the  common 
stock  of  the  science,  the  references  have  been  sometimes  omitted, 
or  an  initial  letter  only  retained.  There  are,  however,  some  works 
to  which  a  more  particular  acknowledgment  is  due.  Those  of 
Bergman  and  Scheele  ;  the  Lectures  of  Dr.  Black,  by  Robison  ; 
the  System  of  Dr.  Thomson,  in  all  its  editions,  and  also  his  more 
recent  work  on  the  First  Principles  of  Chemistry  ;  the  Dictionaries 


PREFACE.  V 

of  Nicholson,  Aikins,  and  Ure,  the  Compendium  of  Dr.  Hare,  the 
Dispensatory  of  Dr.  Coxe,  the  Technology  of  Dr.  Bigelow,  the 
Operative  Chemist  of  Gray,  and  the  Chemical  Manipulation  of  Mr. 
Faraday  ;  the  System  of  the  late  Dr.  Murray,  and  his  Elements,  ably 
edited  by  his  son  ;  as  also  the  writings  of  Mr.  Dalton ;  the  works  of 
Lavoisier,  Chaptal,  Berthollet,  and  Fourcroy,  the  System  of  Thenard, 
in  its  most  recent  edition,  and  his  miscellaneous  writings,  especially 
in  connexion  with  Gay-Lussac ;  and  those  of  Dr.  Priestley,  Bishop 
Watson,  Mr.  Parkes,  Prof.  Berzelius,  and  Sir  H.  Davy,  including 
also  his  Elements — these  are  among  the  leading  authorities,  although 
it  would  be  easy  to  increase  the  catalogue.* 

A  recent  work  by  Dr.  Turner,  of  the  London  University,  has 
been  of  great  utility.  It  is  highly  scientific  and  very  exact,  particu- 
larly on  the  facts  and  doctrines  of  definite  and  multiple  proportions, 
and  combining  equivalents  ;  and  many  of  its  details  have  been  adopted. 

But  the  work  to  which,  more  than  to  any  other,  the  author  of  this 
is  indebted,  is  the  Elements  of  Dr.  Henry.  All  its  numerous  edi- 
tions have  been  attentively  studied,  and  among  the  facts  that  have 
been  cited  from  it,  the  statements  of  the  proportions  of  bodies,  and 
especially  of  the  salts,  are  the  most  prominent.  In  numerous  critical 
comparisons,  made  between  it  and  the  original  memoirs,  abundant 
evidence  has  been  obtained  of  the  great  exactness  of  the  respectable 
author,  whose  abstract  always  reflects  an  image  of  the  original, 
diminished  indeed,  but  perfect  in  every  feature.  No  writer  on 
chemistry,  in  the  English  language,  surpasses  Dr.  Henry  in  fidelity, 
perspicuity  and  good  judgment.  For  twenty  years,  his  work  was  the 
text  book  of  the  classes  in  this  Institution,  and  it  ceased  to  be  used 
here  only  when,  on  account  of  its  increased  size  and  cost,  it  ceased 
to  be  reprinted.  Three  editionsf  of  it  with  notes,  were  published  ex- 
pressly for  the  students  of  Yale  College ;  there  have  been  three 
English  editions  since  the  latest  American,  J  and  the  author's  eleventh, 
with  his  last  revision,  has,  through  his  kindness,  been  just  received. 


*  Many  French  as  well  as  English  Journals  of  Science  have  been  also  examined. 

t  Besides  two  subsequently,  by  Professors  Coxe  and  Hare,  of  the  Univ.  of  Penn. 

t  Since  it  has  become  difficult  to  obtain  this  work,  the  valuable  Manual  of  Dr. 
Webster,  on  the  basis  of  Brande,  has  'been  recommended  to  the  classes.  Few 
works  on  Chemistry  contain  so  much  important  information. 


VI  PREFACE. 


To  the  following  gentlemen,  the  author  of  this  work  tenders  his 
acknowledgments;  to  Prof.  Edward  Hitchcock  and  Prof.  J.  W. 
Webster,  who  were  consulted  in  the  revisal  of  the  earlier  proofs ; 
but  to  Professors  Griscom,  Torrey  and  Olmsted,  and  to  Mr.  C.  U. 
Shepard,  assistant  in  the  chemical  department  of  Yale  College,  a 
more  particular  expression  of  thanks  is  due,  for  the  trouble  which 
they,  by  request,  have  taken,  in  reading  nearly  all  the  proofs.  Their 
individual  suggestions  are  occasionally  designated ;  and  while  the 
work  has  been  much  benefitted  by  their  judicious  criticisms,  they  are 
fully  exonerated  from  any  responsibility  either  for  its  errors,  or  its 
deficiences.  The  errors  that  have  been  detected,  and  which  were 
of  such  a  character  as  to  affect  the  sense,  have  been  registered,  as 
usual,  in  a  table  of  errata,  although  the  corrections  for  most  of 
them  are  generally  obvious  from  the  context.  As  other  errors  will 
doubtless  be  observed,  the  author  requests,  as  a  particular  favor, 
that  they  may  be  promptly  communicated  to  him. 

If  it  does  not  excuse,  it  may  account  for,  some  inadvertencies, 
when  it  is  known,  that  an  arduous  and  responsible  work  was  written 
and  printed,  under  the  unremitting  pressure  of  absorbing  and  often 
conflicting  duties.  Life  is  flying  fast  away,  while,  in  the  hope  of 
discharging  more  perfectly  our  obligations  to  our  fellow  men,  we 
wait  in  vain,  for  continued  seasons  of  leisure  and  repose,  in  which 
we  may  refresh  and  brighten  our  faculties,  and  perfect  our  know- 
ledge. After  we  are  once  engaged  in  the  full  career  of  duty,  such 
seasons  never  come ;  our  powers  and  our  time  are  placed  in  inces- 
sant requisition ;  there  is  no  discharge  in  our  warfare  ;  and  we  must 
fight  our  battles,  not  in  the  circumstances  and  position  which  we 
would  have  chosen,  but  in  those  that  are  forced  upon  us,  by  impe- 
rious necessity. 
Yale  College,  1830. 


CONTENTS  OF  VOLUME  I. 


Page. 

PLAN  OF  THE  WORK,  -            -            1 

INTRODUCTION,                                           -  -            .            -      7 

PART  I. — IMPONDERABLE  AGENTS. 

Sec.  I. — LIGHT,  .             .          35 

Its  materiality — velocity,  -             -25 

Its  refraction,  .             -          26 

Solar  phosphori,  -             -             -    29 

Its  chemical  agency,  -          31 

"   action  on  animals  and  vegetables,  -             -             -    32 

"       "        "    mineral  bodies,  -          33 

"   connection   with   magnetism — sources  of  light — 

Leslie's  Photometer,  -             -             -    34 

Sec.  II. — HEAT  OR  CALORIC,  .           35 

General  nature,  -  ~                " 

Conclusions,                                      -  42 

Effects,  .    44 

1.  Expansion,                       -  " 
Thermometers,  -      -      -    54 

2.  Distribution  of  Temperature,     -  63 
Conduction — Radiation,       -  -    65 

3.  Congelation  and  Liquefaction,   -  82 

4.  Vaporization  and  Gasification,  -    84 
Steam  Engines,  92 

5.  Spontaneous  evaporation,    -  -  104 
Effects— cold,  &c.  105 
Wollaston's  cryophorus,       -  116 

6.  Ignition  or  Incandescence,  117 

7.  Capacity  for  Heat — Specific  Heat,  -  1 19 

8.  Combustion,      -  126 
Sec.  III. — APPENDIX  TO  CALORIC — SOURCES  OF  HEAT   AND 

COLD,  127 

Blowpipe,  128 

Table  of  freezing  mixtures,      -  136 

Sec.  IV. — ATTRACTION,        -  137 

Gravitation,     - 

Magnetism — Galvanism,    -  138 

Cohesion  and  Aggregation,      -  139 

Crystallization,      -  141 

Chemical  Attraction  or  Affinity,  151 

Definite  proportions,  160 


Vlll  CONTENTS. 

Page. 

Chemical  equivalents,  164 

Appendix  to  Attraction,  172 

Rules  of  Philosophizing,   -  173 

Apparatus  and  Operations,       -  174 

Specific  gravity,  method  of  ascertaining,  -       177 

Pneumatic  Cisterns,        -  181 

Gazometers,  -       183 

PART  II. — PONDERABLE  BODIES. 

Sec.  I. — OXYGEN, 

Action  on  Combustibles,     -  187 

Relation  to  animal  life,  190 

Sec.  II. — NITROGEN  OR  AZOTE,  -      r        -       193 

Atmosphere,      -  195 

Sec.  III.— HYDROGEN,  -       201 

Properties,  &c.  202 

Water — synthesis,  -  -       207 

"          analysis,  209 

"          its  properties,  -       211 

Deutoxide  of  Hydrogen,  215 

Eudiometry  by  Hydrogen,  -       217 

"            "    spongy  Platinum,  221 

Hare's  Oxy-Hydrogen  Blowpipe,  -                          -      224 

ALKALIES. 

Preliminary  Remarks  and  Statement,  -  228 

Sec.  I. — AMMONIA,  -  -  230 

Composition,  -  233 

Sec.  II.— POTASSA,  -  -  238 

Properties,  240 

Uses,  &c.    - 

Potassium,  -  . 

Decomposition  of  Potassa  and  Soda,  -       244 

Properties  of  Potassium,  247 

Sec.  III.— SODA,  -  251 

Sodium,  253 

Sec.  IV.— LITHIA,  -  -  257 

EARTHS. — Introductory  Remarks,  259 

EARTHS. 

I.— LIME,           ...  -       261 

Calcium,  264 

II.— BARYTA,      -  -       267 

Barium,  268 

HI. — STRONTIA,  270 

Strontium,          ....  271 


CONTENTS.  IX 

Page. 

IV. — MAGNESIA,  -       272 

Magnesium,        -  274 

V.— SILICA,  -      274 

Silicon,                                                                   -  277 

Glass,  -       279 

VI.— ALUMINA,                                                               -  283 

Porcelain  and  Pottery,         -             -  -       286 

Aluminium,                                                 -             -  293 

VII.— ZIRCONIA, 295 

Zirconium,         .....  297 

VIII.— GLUCINA,    ......       298 

Glucinium,  299 

IX.— YTTRIA,      -             -  " 

Yttrium,  301 

X.— THORINA — Thorium,                        -  " 

SIMPLE    INFLAMMABLE    AND    ACIDIFIABLE    BODIES,    (not  metallic,)  AND 
THEIR    COMBINATIONS    WITH    THE    PRECEDING    BODIES. 

Sec.  I.— HYDROGEN,  (see  p.  201,)  -      302 

Sec.  II. — SULPHUR,            .....  « 

ACIDS. — Preliminary  Remarks,  -       305 

General  Properties — their  nomenclature,  307 

Sulphuric  Acid,        -  «' 

Sulphurous  "     -             -             -             -             -  313 

SALTS. — Introductory  Remarks,       -  -       318 

Nomenclature,                 -                                        -  319 

Sulphates  of  Alkalies  and  Earths,  -       321 

Sulphate  of  Potassa,  " 

Bi-sulphate  of  do.     -  -       323 

Sulphate  of  Soda,  324 

"            Ammonia,          -  -      325 

"             Lime,           -            -            -  326 

"             Baryta,                                         -  -      328 

"             Strontia,  330 

"             Magnesia,                                   -  -      331 

"             Alumina  and  Alum,              -             -  334 

Sulphites  of  Alkalies  and  Earths,                 -  -      337 

Sulphite  of  Lime — of  Baryta,      -  " 
"             Strontia,   Magnesia,   Alumina,   Potassa, 

Soda,  and  Ammonia,                    -  -       338 

Hypo-Sulphurous  Acid,              -  339 

Hypo-Sulphites,       -  -         " 

Hypo-Sulphuric  Acid  and  Hypo-Sulphates,  340 

Sulphuretted  Hydrogen,       -  -       341 

Bi-Sulphuretted  Do.       -  344 

VOL.  II.  2 


X  CONTENTS. 

Page. 

Hydro-Sulphurets,  345 

"                    of  Potassa,  346 
"   ^                of  Soda,  Ammonia,  Lime,  Baryta,      347 

"                     of  Strontia,  Magnesia,  348 
Sulphuretted  Hydro-Sulphurets — General  Characters,       " 
of  Potassa, 

of  Soda,  Ammonia,  Lime,  349 

of  Baryta,  Strontia,  -       350 

of  Magnesia,  351 
Sulphurets  of  Alkalies  and  Alkaline  Earths, 

Sec.  III.— CARBON,  355 

Charcoal,     -  356 

Uses,      -  360 
Sulphuret  of  Carbon, 

Carbonic  Acid,                                -  365 

Carbonates,  375 

of  Potassa,  376 
Bi-Carbonate  of  Do. 

Carbonate  of  Soda,  (soda-water)  379 
Bi-Carbonate  of  Do. 
Carbonates  of  Ammonia, 

"            Lime,  •       387 

Baryta,  389 

Strontia,  -       391 

"            Magnesia,  392 

Carbonic  Oxide,       -  -       395 

Carburetted  Hydrogen  Gases — Olefiant  Gases,  399 

Naphthaline,       -  407 

Coal  and  Oil  Gas,     -  -       408 

Davy's  Safety  Lamp,      - 

Cyanogen,  417 
Prussic  or  Hydro-Cyanic  Acid, 
Sec.  IV.— PHOSPHORUS, 

History — preparation—properties,  -       418 

Atmospheric  Eudiometer  by  Phosphorus,  420 
Phosphoric  Acid,      - 

Phosphorous  Acids,  425 
Hypo-Phosphorous  Acid,     - 

Phosphates,  429 

Phosphate  and  Bi-Phosphate  of  Potassa,      -  -       430 

Phosphate  of  Soda,  431 

"          and  Bi-Phosphate  of  Ammonia,  433 

"          of  Soda  and  Ammonia — of  Lime,       -  434 

"          of  Baryta,  -       437 

"          of  Strontia — of  Magnesia,      -  438 

"          of  Ammonia  and  Magnesia,  439 


CONTENTS.  XI 

Page. 
Binary  Compounds  of  Phosphorus    with   various 

bases,  -       440 
Phosphuretted  Hydrogen  and  varieties,  " 

Phosphuret  of  Sulphur,  -       444 
"                Lime,       -  445 

Sec.  V. — NITROGEN — its  Combinations  with  preceding  simple 

bodies,  -       446 
Nitric  Acid,                                                   -  «« 

Deutoxide  of  Nitrogen  or  Nitrous  Gas,  -       453 
Nitrous  Acids — general  explanation,       -  456 

Hypo-Nitrous  Acid,  -       457 
Nitrous  Acid,      -  459 

Appendix  to  History  of  the  Nitrous  Acids,  -      461 
Nitrates  of  Alkalies,  464 

"  Potassa,  -  " 

Soda,  -  -  473 

"  Ammonia,  -       474 

Nitrous  Oxide  or  Protoxide  of  Nitrogen,  476 

Nitrates  of  the  Earths,  -  -       486 

Baryta,  -  « 

Strontia,  -       486f 
Lime,                                                    -  487 

Magnesia,  ....       43$ 

Magnesia  and  Ammonia — of  Alumina,  489 

Nitr  tes,  -  -  -  -  •    * 

Recapitulation  of  Compounds  of  Oxygen  and  Nitro- 
gen, .....  «• 
Sec.  VI.— BORON  and  BORACIC  ACID,                                                   491 
Boracic  Acid,                          -  " 
Boron,                 -     .                                                            494 

Borate  of  Potassa — Bi-Borate  of  Soda  or  Borax,  -       496 
"        Ammonia — Baryta — Strontia,                -  498 

"        Lime — Magnesia — Alumina,  -       499 
Sec.VII.-FLUORic  ACID,  " 

Fluo-Silicic  Acid  Gas,  -  -  -       502 

Fluo-Boric  Acid  Gas,      -  505 

Fluoric  Principles,  -       506 
Fluates — General  Characters,     -  508 

Fluate  and  Bi-Fluate  of  Potassa,       -  -  -       509 

"      of  Soda — of  Ammonia,     -  510 

"          Baryta — Strontia — Lime,  -       511 
"          Magnesia — Alumina,  512 

Silica,        -  -       513 
Sec.  VIII.— SELENIUM,       •  " 

Oxide  of  Selenium,  -       515 
Selenious  Acid,  516 

Selenic  Acid,         -  517 


ERRATA — VOL.  I. 


Page  49, 1.  6  fr.  top,  after  with,  dele  one  of;  and  after  another,  insert  of  the  same. 
— p.  58, 1.  7  fr.  bot.  dele  or  melting  snow. — p.  128, 1. 15  fr.  bot.  for  illustrating,  read 
illustrated. — p.  139,  (g.)  after  chlorine,  read  and  bromine. — p.  148, 1.  19  fr.  top,  after 
which,  read  have. — p.  155, 1.  4  fr.  top,  dele  except  the  first. — p.  161, 1.  3  and  4  fr.  top, 
for  40,  read  78 ;  and  for  78,  read  40.— p.  162, 1.  7  fr.  top,  for  1,  read  2.— p.  168, 1. 10  fr. 
top,  after  +  0.0694  x  3  =,  add  1.1804. — p.  169, 1.  27  fr.  top,  before  acid,  read  oxygen 
of  the.— p.  180,  1.  5  fr.  top,  for  x  18,  read  +18.— p.  186,  4(c.)  before  for,  read  grs.— 
p.  201,  2(a.)  after  muriatic,  read  acid. — p.  202,  4(c.)  for  0.694,  read  .0694 ;  and  p. 
310, 1.  11  fr.  bot,  373, 1.  5  and  6  fr.  bot.,  403,  (6.),  408, 1.  9  fr.  bot.  tbe  dec.  point 
is  either  misplaced  or  omitted. — p.  232,  (6.)  for  weight  18.17  grs.,  read  weight 
of  100  cub:  in.  is,  18.17  grs.— p.  241, 1.  15  fr.  top,  after  of  the,  read  ashes  of 
the. — p.  248, 1.  18  fr.  top,  before  potash,  read  nitrate  of. — p.  262,  1.  17  fr.  top, 
after  32°  for  .  A  read  ,  a. — p.  288, 1.  10  from  bot.  before  conical,  read  and. — p.  297, 
(c.)  (in  a  few  copies,)  for  zirconia,  read  zirconium. — p.  315,  (fe.)  for  -  31,  read  +  31. 
— p.  326,  1.  2  fr.  top,  interchange  1  and  2. — p.  332,  (i.)  dele  carbonate  of. — p.  337, 
1.  1  fr.  bot.  for  40,  read  32.— p.  338, 1.  11  and  12  from  bot.  for  9  =  108  =  172,  read  8 
=  72  =  136.— p.  339, 1. 16  and  17  fr.  top.  for  32,  read  16  and  for  40,  read  24.— p.  340, 
1.  4  fr.  bot.  for  1,  read  2;  1.  25  fr.  top,  for  ous,  read  ic,  and  vice  versa,  p.  426, 1. 
10. — p.  355, 2  (a.)  1. 18  fr.  top,  for  it,  read  charcoal. — p.  357, 1.  20  fr.  top,  for  oxide  35, 
read  acid  35.— p.  361,  (kk.)  1. 16  fr.  top,  for  of  iron,  read  of  lime.— p.  371, 1.  21  fr.  top, 
(n.)  for  fluid,  read  ice  and  omit  the  paragraph  (<?.) — p.  383,  bot.  1.  after  once,  read  in. 
— p.  392, 1.  15  fr.  top,  interchange  70  and  30. — p.  399, 1. 17  fr.  top,  after  containing, 
read  in  proportion  to  the  oxygen. — p.  424,  1.  21  fr.  top,  for  are,  read  is. — p.  425, 
bot.  dele  note  marked  t. — p.  427, 1.  7  fr.  top,  for  phosphorus,  read  phosphorous. — p. 
439, 1.  10  fr.  top,  interchange  20  and  28.— p.  506, 1. 24  from  top,  after/or,  add  future 
trial.— p.  517, 1.  21  fr.  top,  for  selenic,  read  selenious. 


PLAN  OF  THE  WORK. 


I.  INTRODUCTORY  REMARKS,  on  the  general  nature  and  objects  of 
the  physical  sciences,  especially  of  chemistry,  and  on  its  connexion 
with  the  other  departments  of  natural  knowledge. 

II.  THE  IMPONDERABLE  AGENTS. 

An  outline  of  the  great  powers  which  produce,  influence  and  mod- 
ify chemical  phenomena,  exhibiting  their  nature  as  far  as  it  is  under- 
stood, and  their  effects  as  far  as  they  are  ascertained. 

They  are  treated  of  in  the  following  order — 

1.  Light, 

2.  Heat  or  caloric, 

3.  Galvanism, 

4.  Attraction. 

Galvanism,  including  electricity  and  magnetism,  as  far  as  they  are 
chemical  agents,  is  only  sketched  in  a  very  general  way,  in  the  early 
part  of  the  work  :  the  fuller  development  is  reserved  for  the  conclu- 
sion, after  all  the  facts  of  the  science  have  been  explained,  and  when, 
as  the  illustrations  are  drawn  from  every  part  of  chemistry,  they  will 
of  course  be  best  understood. 

III.  THE  PONDERABLE  BODIES. 

I.  Inorganic  bodies,  including  all  that  do  not  belong  to  the  animal 
and  vegetable  kingdoms. 

1 .  Oxygen;  one  of  the  bodies  that  exist  in  greatest  abundance,  and 
whose  functions  and  relations  are  the  most  important,  is  first  describ- 
ed ;  and  its  properties  are  continually  illustrated  in  the  progress  of 
the  work. 

I  have  not  thought  it  best  to  describe  the  simple  substances  in  un- 
interrupted succession.  Such  a  method  does  not  appear  to  me  to 
present  advantages,  sufficient  to  compensate  for  the  inconvenience 
of  plunging,  at  once,  into  the  most  complex  parts  of  the  science, 
which  must  be  done,  if  we  would  draw  the  elementary  bodies  from 
their  combinations,  and  present  them,  in  the  beginning,  in  a  connect- 
ed view. 

For  this  reason,  chlorine  with  all  its  complex  relations,  and  difficult 
theoretical  points,  is  reserved  until  the  student  has  become  familiar 

1 


2  PLAN  OF  THE  WORK. 

with  numerous  important  chemical  facts,  and  until  those  substan- 
ces by  whose  aid  it  must  be  obtained,  have  been  exhibited.  It  is 
then  easy  to  revert  both  to  the  simple  and  compound  bodies  that  have 
preceded,  and  to  explain  the  relations  of  chlorine  to  them ;  and  the 
similarity  between  chlorine  and  oxygen,  as  supporters  of  combustion, 
can  then  be  made  even  more  intelligible,  than  in  the  outset. 

It  is  obvious,  that  wherever  chlorine  may  be  placed,  iodine  must 
follow,  because  of  the  great  similarity  in  the  properties  of  the  two  bo- 
dies, and  because,  alone,  iodine  would  be  less  intelligible  than  chlo- 
rine. Upon  this  plan  also,  the  origin  of  iodine  from  the  marine 
plants  and  other  natural  sources,  admits  of  more  intelligible  explana- 
tion. The  new  body  bromine,  from  its  character  and  affinities,  nat- 
urally comes  in  immediately  after  chlorine  and  iodine.  It  has  been 
the  practice,  of  late  years,  to  rank  oxygen,  chlorine,  and  iodine  to- 
gether, because  they  have  similar  electrical  and  chemical  relations : 
and  fluorine,  a  principle  which  is,  as  yet,  known  only  in  name,  ha? 
been  added  to  the  list.  As  our  evidence  of  the  simplicity  of  any 
body  is  merely  negative,  it  is  possible  that  all  the  bodies  now  re- 
ceived as  simple,  may  be  hereafter  decomposed,  and  every  table  of 
simple  bodies  must  be  regarded  as  an  assumption,  founded  on  the 
negative  fact,  that  those  bodies  have  not  yet  been  decomposed. 

The  natural  process  of  acquiring  knowledge  is  the  analytical,  or 
the  progress  from  the  complex  to  the  simple,  from  the  whole  to  its 
parts ;  the  shortest  is  the  synthetic,  that  is,  from  the  simple  to  the 
complex ;  from  the  parts  to  the  whole ;  and  diis  is  the  course  now 
more  generally  pursued  in  chemistry.  If  our  knowledge  were  per- 
fect, this  would  be  not  only  the  most  obvious,  but  the  best  process  ; 
and  perhaps  that  mode  will  be  found  to  combine  most  advantages 
which  unites  them  both.  With  this  view,  I  have,  therefore  some- 
times adopted  the  one  and  sometimes  the  other,  aiming  to  present  the 
most  important  elements  and  combinations  as  early  as  possible. 

The  atmosphere  and  water  are  concerned  in  nearly  all  chemical 
phenomena. 

2"!  I  have  therefore  introduced,  after  oxygen,  an  account  of  nitro- 
gen, and  then,  at  the  next  step,  the  composition  and  leading  mechan- 
ical properties  of  the  atmosphere. 

3.  Then  follows  hydrogen,  with  the  composition  and  properties  of 
water ;  and  as  a  natural  appendage,  the  compound  or  oxy-hydrogen 
blowpipe.     We  are  thus  early  put  in  possession  of  this  useful  and 
splendid  instrument.* 

4.  The  alkalies  and  acids  are  among  the  most  important  of  the 
chemical  agents,  and  it  is  necessary  that  their  properties  should  be 

*  This  instrument  is  in  my  laboratory,  kept  in  readiness,  and  is  used  as  occasion? 
require,  through  the  whole  course. 


PLAN  OF  THE  WORK.  3. 

understood  as  early  as  possible.  It  is  perhaps  not  quite  obvious 
which  should  be  first  presented  to  the  student.  Here,  however,  as 
well  as  in  every  other  arrangement,  it  is  as  desirable,  as  it  is  difficult* 
to  avoid  anticipatipn :  begin  where  we  may,  something  must  be 
brought  into  view  that  has  not  been  explained ;  the  only  proper 
course  is,  to  anticipate  as  little  as  possible,  and  when  it  is  unavoida- 
ble, to  give,  at  the  moment,  the  explanation  necessary  to  render  the 
step  intelligible ;  or  to  refer  to  the  proper  source  whence  it  may  be 
obtained.  In  teaching,  I  have,  with  respect  to  the  priority  of  acids 
and  alkalies,  tried  both  methods,  and  have  concluded,  that  the  alka- 
lies are  presented  first,  with  most  advantage.  The  earths,  of  course, 
follow  in  the  train  of  the  alkalies. 

I  have  not  thought  it  advantageous  to  break  up  the  natural  classes 
of  alkalies  and  earths,  and  place  them  among  the  metallic  oxides.* 
Strict  logic  would  justify,  perhaps  require  such  a  method ;  but  the 
convenience  of  teaching  and  learning,  is  in  my  view,  decidedly 
against  it ;  and  there  is  in  fact,  no  more  difficulty  in  learning  the  pro- 
perties of  potassium  and  sodium  under  potassa  and  soda,  man  of  the 
latter  under  the  former.  Still,  when  the  list  of  the  metals  is  given, 
these  two  metals  and  others  of  a  similar  character  can  be  included, 
and  a  proper  reference  can  be  made  to  the  places  where  the  de- 
scription of  them  will  be  found. f 

In  teaching,  the  great  object  should  be,  to  find  our  way  into  the 
mind  of  the  pupil^  and  to  fix  there>  the  knowledge  that  we  present 
to  him.  He  is,  ordinarily,  no  judge  of  our  theoretical  views  with  re- 
gard to  classification  and  arrangement ;  he  will,  in  most  cases,  even  fail 
to  understand  us,  when  we  discuss  them ;  and  he  will  be  best  sat- 
isfied, with  that  course  which,  in  the  most  interesting  and  intelligible 
manner,  presents  to  him  the  greatest  amount  of  useful  knowledge. — 
Both  in  my  public  courses  of  lectures,  and  in  the  present  work,  I  have 
therefore,  considered  this  object  as  paramount  in  importance  to  ev- 
ery other. 

5.  The  simple ,  non-metallic  combustible  bodies  are  next  intro- 
duced, both  because  their  history  is  remarkably  interesting  and  in- 
structive, and  because  they  are  the  bases  of  the  most  important  acids, 
whose  history  is  easily  and  naturally  developed,  in  connexion  with 
that  of  these  combustibles.  Hydrogen,  already  described  along 
with  water,  comes  again  into  view  as  the  basis  of  muriatic ,  acid. 
Nitrogen,f  although,  in  a  popular  sense,  strictly  a  non-combustible  ; 


*  Since  the  metallic  oxides  include  bodies  of  such  widely  different  properties,  I 
can  see  no  impropriety  in  distributing  them  into  classes.  I  am  supported  in  this  ar- 
rangement by  the  late  edition  of  Murray. 

t  The  new  vegetable  alkaline  principles  are  so  peculiar  in  most  of  their  properties, 
that  there  would  be  no  advantage  in  classing  them  with  the  alkalies  commonly  so 
called. 

t  Also  before  described  in  coanexion  with  the  history  of  the  atmosphere. 


4  PLAN  OF  THE  WORK. 

still,  because  it  possesses  affinities,  and  produces  in  combination,  re- 
sults entirely  similar  to  those  of  the  combustibles,  is  thrown  into  the 
same  class,  for  the  purpose  of  bringing  forward  the  important  acids 
and  oxides  of  which  it  is  the  basis. 

Two  of  the  least  important  of  the  simple  combustibles,  boron  and 
selenium,  are  reserved  until  this  period  :  their  history  bears  no  very 
important  relation  to  that  of  most  of  the  other  bodies,  but,  as  they  too 
form  acids,  they  are  disposed  of  in  the  train  of  the  other  combustibles, 
and  of  the  great  agents  that  sustain  combustion. 

Fluoric  acid,  which  although  undecomposed,  has  without  doubt,  a 
combustible  base,  is  naturally  assigned  to  the  same  place,  in  the  class- 
ification, and  from  its  combining,  in  an  interesting  manner,  with  boron, 
it  comes  immediately  after  that  body,  and  before  selenium,  whose 
character  is  rather  anomalous,  but  more  allied  perhaps  to  the  combus- 
tibles than  to  the  metals,  where  many  have  placed  it. 

6.  Chlorine  and  Iodine  and  Bromine  are  introduced  after  the  ele- 
mentary non-metallic  combustibles  have  been  described,  and  at  a  pe- 
riod when,  as  already  intimated,  their  history  becomes  intelligible. 

The  history  of  bodies,  thus  far  described,  embraces  a  great  part 
of  the  philosophy  of  chemistry,  and  no  small  part  of  the  most  im- 
portant facts  of  the  science.  If  we  were  to  name  any  portion  of 
chemistry,  that  is  more  splendid  in  its  experiments,  and  more  afflu- 
ent in  important  results,  than  another,  it  would  be  that  which  is  in- 
cluded in  the  history  of  the  elementary  combustible  bodies,  especial- 
ly when  we  add  their  relation  to  chlorine  and  iodine,  which  follow  im- 
mediately after  the  simple  inflammables. 

7.  The  metals  come  next,  and  their  history  includes  all  the  re- 
maining elementary  bodies.     There  is  a  general  agreement  among 
authors,  as  to  the  place  which  most  of  the  metals  are  to  occupy  in  a 
systematic  arrangement,  and  no  one  at  present  thinks  of  presenting 
them,  as  some  formerly  did,  in  the  beginning,  along  with  other  ele- 
mentary bodies.     It  is  true  that  some  of  them  are  used  in  the  de- 
monstrations that  precede,  but  as  most  of  the  facts  are  familiar,  and 
the  phenomena  intelligible,  this  creates  no  difficulty ;  every  one  can 
understand,  for  instance,  how  iron  decomposes  water,  and  he  will 
comprehend  how  sulphuric  acid  aids  in  that  process,  just  as  well  be- 
fore as  after  he  has  studied  the  properties  of  iron  and  of  the  other 
metals. 

II.  ORGANIC  BODIES. 

They  owe  their  particular  modes  of  existence,  to  the  joint  action 
of  the  laws  of  life  and  of  matter. 

There  is,  of  course,  nothing  elementary  in  this  part  of  the  subject. 
Both  animals  and  plants  must  derive  their  elements  from  the  unor- 


PLAN  OF  THE  WORK.  £ 

ganized  kingdom;  and,  in  relation  to  them,  our  most  interesting 
task  is,  to  trace  the  various  proximate  principles,  in  which  the  ele- 
ments are  combined.  This  part  of  chemistry  is  less  splendid  than 
the  preceding ;  but  it  is  fruitful  in  important  information,  and  much 
of  it  is  applicable  to  common  wants  and  occurrences. 

1.   Vegetable  Bodies. 

We  have  here  only  oxygen,  carbon,  and  hydrogen,  as  essential  to 
the  constitution  of  most  plants ;  nitrogen  is  found  in  some,  and  the 
number  containing  it  is  greater  than  was  formerly  supposed  ;  but 
the  proximate  principles  are  numerous  and  important,  and  the  student 
is  astonished  to  find,  that  such  diversified  results  are  obtained  from  the 
union,  in  different  modes  and  proportions,  of  three  or  four  .elements. 

2.  Animal  Bodies. 

The  few  remarks,  just  made,  are  applicable  here  with  some  quali- 
fications. 

The  same  elements  are  found  as  in  vegetables;  and  nitrogen, 
instead  of  being  an  occasional,  is  nearly  a  constant  principle.  The 
number  of  proximate  principles  is  however  more  limited  than  in  the 
vegetable  kingdom,  but  their  history  is  instructive  and  important. 

All  are  agreed  in  giving  a  late  place  to  the  chemistry  of  organ- 
ized bodies ;  for  it  is  obvious,  that  it  would  not  be  intelligible  at  an 
earlier  period. 

GALVANISM. 

It  has  been  already  stated,  that  this  power,  although  mentioned 
and  described,  generally,  among  the  imponderable  agents,  is  better 
understood,  after  the  student  has  been  made  acquainted  with  all  the 
Qther  facts  in  chemistry. 

As  a  general  power,  its  most  important  function  is,  in  the  decom- 
position of  bodies,  ending  in  the  transfer  of  their  elements  and  prin- 
ciples, to  its  respective  poles.  This  being,  in  the  begining,  ex- 
plained, and  experimentally  proved,  in  connexion  with  the  history  of 
the  other  imponderable  agents,  there  is  no  difficulty  in  marking  and 
understanding  the  polarity  of  each  body  as  we  proceed,  and  when 
we  come  to  present  Galvanism,  in  form  and  in  fulness,  at  the  end 
of  the  course,  thislgeneral  arrangement  of  both  elements  and  prox- 
imate principles  can  be  recapitulated,  and  experimentally  illustrated 
in  detail,  with  great  advantage. 


(3  PLAN  OF  THE  WORK. 

Neither  is  there  any  thing  in  the  earlier  parts  of  the  course  that 
renders  it  necessary  to  exhibit  the  deflagrations,  ignition,*  and  mus- 
cular shocks  produced  by  this  agent ;  and  which,  when  presented  at 
the  conclusion,  with  the  aid  of  powerful  apparatus,  terminate  a 
long  course  of  demonstrations  and  reasoning,  with  the  most  brilliant 
finish  that  can  be  desired. 

So  far  as  the  natural  history  of  bodies,  and  their  analysis,  and  ap- 
plications to  use  are  proper  subjects  of  attention  in  a  concise  Manual, 
I  have  thought  it  better,  in  general,  to  give  the  facts,  in  connexion 
with  the  different  articles  to  which  they  belong,  rather  than  at  the  end 
of  the  work. 

The  numerical  tables  that  are  not  given  in  the  body  of  the  work, 
are  of  course  contained  in  an  appendix.  They  are  necessarily  se- 
lected from  different  authors,  and  although  little  used  by  the  student 
of  mere  elements,  are  important  for  occasional  reference. 


*  Dr.  Hare  however  uses  a  small  calorimotor  to  explode  gases ;  and  his  larger  in- 
struments exhibit  results,  more  splendid  and  interesting,  than  any  other  Galvanic 
apparatus  with  which  I  am  acquainted. 


INTRODUCTION.* 


I.  PHENOMENA  AND  SCIENCES  CONNECTED  WITH  NATURAL  OB- 

.'JECTS. — As  man  is,  necessarily  and  constantly,  conversant  with 
natural  objects,  he  cannot,  if  he  would,  be  wholly  withdrawn  from 
the  physical  phenomena,  which  are  perpetually  exhibiting  the  relations 
of  material  things. 

In  ancient  times,  every  thing  relating  to  natural  bodies  was  inclu- 
ded under  PHYSICS,  and  this  term  therefore,  comprised  NATURAL  HIS- 
TORY, NATURAL  PHILOSOPHY,  and  CHEMISTRY.  Since  the  more  ex- 
tended cultivation  of  natural  science,  and  particularly  since  the  time 
of  Bacon  and  Newton,  the  external  appearances!  of  natural  bodies 
have  been  included  under  NATURAL  HISTORY,  and  their  analysis  and 
composition  are  assigned  to  CHEMISTRY. 

1 .  NATURAL  PHILOSOPHY  occupies  itself  with  the  general  affections 
and  mechanical  laws  of  bodies,  with  the  physical f  laws  of  light,  heat, 
magnetism  and  electricity,  and  in  short,  with  all  that  is  not  inclu- 
ded in  the  two  other  great  divisions  of  natural  science.  It  is  a 
science  of  high  importance ;  it  is  in  every  university,  a  regular 
branch  of  education,  and  in  every  enlightened  country,  an  object  of 
diligent  cultivation.  It  is  founded  on  observation  and  experiment, 
and  the  application  of  the  mathematics,  in  aid  of  its  researches,  has 
given  them  both  dignity  and  certainty. 

The  mathematics  are  applied  to  most  of  the  physical  sciences, 
not  excepting  Chemistry. 

They  are  founded  on  intuitive  truths,  and  embrace  the  relations  of 
magnitude  and  number.  In  these  relations,  every  one  is  interested, 
and  were  there  no  other  use  in  mathematics  than  to  supply  us  with 
precise  ideas  and  terms,  for  the  forms  of  external  things,  and  with 
correct  expressions  for  the  distances  and  positions  of  objects,  they 
would  relieve  us  from  much  obscurity  and  confusion.  The  study 
of  the  mathematics,  greatly  invigorates  and  sharpens  the  understand- 
ing, by  establishing  habits  of  patient  investigation,  of  exact  method, 
and  close  reasoning,  besides  conducting  us  also  to  many  important 
practical  results.  The  mensuration  of  heights  and  distances,  the 
computations  of  quantity,  both  superficial  and  solid,  and  the  linear 

*  Revised  and  abridged  from  an  introductory  lecture  of  the  author,  published  iu 
October,  1828. 

t  In  part  also  under  Natural  Philosophy. 
i  As  distinguished  from  the  chemical  laws. 


$  INTRODUCTION, 

and  angular  measurements  of  perspective,  and  of  navigation,  survey- 
ing and  astronomy,  are  among  its  most  familiar  and  obvious  ap- 
plications. 

To  return  to  Natural  Philosophy,  the  student  in  this  science  learns, 
with  pleasure  and  surprise,  that  the  same  power  which  retains  Jupi- 
ter in  his  orbit,  precipitates  a  falling  drop ;  that  a  feather,  a  balloon 
and  a  ship  of  the  line  are  floated  by  statical  pressure ;  that  the  same 
power  causes  a  narrow  column  of  water,  sustained  in  a  tube,  to  raise 
a  weight,  many  thousand  times  greater  than  its  own ;  that  by  its 
means  a  cascade  falls  through  the  atmosphere,  which  in  its  turn, 
raises  a  column  of  water  in  a  pump ;  and  that  gravity  exerts  an 
uninterrupted  dominion  over  atoms,  planets  and  systems.  It  is  seen 
also  by  the  learner,  that  the  mechanical  powers,  so  indispensable  to 
our  existence  and  efficiency,  and  that  the  motions  of  animals  are  de- 
pendent upon  similar  principles,  and  gravity  is  not  unfrequently  the 
immediate  agent. 

The  phenomena  of  LIGHT  are  among  the  most  beautiful  and  in- 
structive of  those  belonging  to  Natural  Philosophy.  The  rainbow 
is  a  splendid  example  of  the  decomposition  of  the  solar  beam,  ef- 
fected by  the  refractive  power  of  the  drops  of  water ;  still,  magnifi- 
cent and  beautiful  as  it  is,  it  excites  perhaps  less  astonishment  in 
the  beholder,  than  the  colors  exhibited  by  the  common  prism  in  a 
darkened  room,  where  the  iris,  although  very  small,  compared  with 
the  bow,  is  more  intense,  and  is  brought  within  our  more  immediate 
view.  The  astonishing  results  produced  by  the  solar  focus,  in  which 
the  concentrated  beams  melt  and  dissipate  metals  and  stones ;  the 
surprising  and  beautiful  effects  of  the  common,  the  lucernal,  and 
the  solar  microscope,  in  whose  fields  of  vision  motes  become  beams, 
and  animalculse  rival  the  gigantic  animals ;  the  wonderful  illustrations 
of  the  eye,  on  whose  retina,  either  uncovered  by  dissection,  or  imi- 
tated by  art,  are  seen  painted  distinctly,  in  all  their  varieties  of  color 
and  of  form,  the  fields,  the  groves,  the  sky,  the  faces  of  men,  and  all 
the  objects  that  surround  us  ;  the  power  of  the  telescope,  by  which 
we  penetrate  into  the  awful  darkness  of  space,  and  look  through  the 
veil  that  covers  the  heavenly  bodies ;  these  are  a  few  of  the  won- 
ders which  natural  philosophy  teaches  respecting  light,  that  incom- 
prehensible emanation,  without  which  the  creation  would  become 
cheerless  and  desolate,  and  animated  beings  would  dwindle  and  die. 

THE  ATMOSPHERE,  in  tranquillity,  is  little  regarded  except  as  af- 
fording the  means  of  comfortable  respiration  to  the  whole  animal 
world  ;  but,  disturbed  in  its  statical  pressure,  by  the  influence  of 
heat,  it  generates  not  only  land  and  sea  breezes,  monsoons,  and  trade 
winds,  but  the  hurricane  and  the  tornado.  Navies  are  overwhelmed 
in  the  waves ;  the  oak  and  the  cedar  are  prostrated ;  and  man  and 
his  works,  his  towers  of  strength,  ami  his  pinnacles  of  pride  are  level- 


INTRODUCTION.  9 

led  with  the  dust.  The  same  atmosphere,  although  invariably  the 
residence  of  the  electric  fluid,  exhibits,  only  occasionally,  decisive 
proof  of  an  energy,  which  pervades  the  material  world.  Excited 
by  causes,  which,  except  in  their  proximate  operation,  are  unknown 
to  us,  the  electric  fluid  fills  the  atmosphere  with  thunder  and  light- 
ning. It  was  reserved  for  Dr.  Franklin  to  prove,  that  lightning  is 
identical  with  the  spares  which  are  obtained  by  friction  from  glass 
or  resin,  or  from  dry  fur,  from  our  apparel  of  silk  or  woollen,  and 
from  many  other  sources.  In  short,  we  now  know  that  all  things  are 
full  of  the  electrical  influence ;  that  we  can  bring  it  down  from  the 
clouds  by  kites,  metallic  rods  and  wires ;  that  we  can  evolve  it  by  our 
machines  of  glass  and  metals,  and  that  by  the  power  called  Galvan- 
ism, using  certain  arrangements  of  metals,  acids,  and  other  substances, 
we  can  produce  it  at  pleasure,  connected  more  or  less  with  the  other 
imponderable  fluids,  in  entire  independence  of  the  weather,  and  of 
the  state  of  the  atmosphere  ;  and  at  the  same  time  we  can  render 
sensible  the  attraction  and  repulsion,  which  are  inseparable  from  its 
excitement. 

Although  the  experiments,  exhibiting  these  facts,  are  sufficiently 
curious,  the  importance  of  the  subject  has,  only  within  a  few  years, 
been  perceived  in  its  full  extent ;  for  it  is  now  believed,  that  the  par- 
ticles of  matter  are  constantly  under  the  influence  of  these  attractions 
and  repulsions,  and  that  they  are  producing,  without  cessation,  de- 
compositions and  new  arrangements. 

Associated,  every  where,  with  electricity,  HEAT  both  modifies  its 
effects,  and  produces  peculiar  phenomena.  The  mild  radiations  of 
the  sun,  and  the  gentle  fluctuations  of  temperature  are  subjects  of 
common  experience,  and  excite  no  particular  surprise.  But  the 
amazing  energy  of  VOLCANIC  ACTION,  far  surpasses  every  other  ex- 
ample of  natural  heat.  Science  is  now  in  a  condition  to  reason,  with 
considerable  probability,  as  to  the  causes  of  volcanic  heat,  and  still 
more,  regarding  those  of  the  accompanying  phenomena  of  earth- 
quakes :  but  leaving  these  for  the  present  out  of  view,  our  attention 
is  arrested  by  the  grandeur  of  the  events,  associated  with  volcanic 
agency. 

The  convulsion  of  the  ground,  not  only  in  the  immediate  vicinity, 
but  often  in  distant  countries ;  the  subterranean  noises,  like  internal 
thunder,  and  the  grating  sound  produced  by  the  rending  of  the  solid 
strata ;  the  violent  emission  of  gases,  steam,  ashes,  sand,  ignited 
stones  and  rocks,  and  eventually  of  the  current  of  lava,  which  flows 
in  a  stream  of  fire  down  the  mountain,  and  over  the  nether  country ; 
the  overthrow  of  the  structures  of  man,  or  their  inhumation  beneath 
the  lava  and  ashes ;  the  lightning  and  thunder,  in  and  above  the  cra- 
ter ;  the  violent  flux  and  reflux  of  the  tides  and  the  strong  agita- 
tion of  the  sea,  alternately  inundating  and  draining  the  adjacent 


10  INTRODUCTION. 

shores ;  the  deluging  torrents  of  rain  and  mud,  and  the  delusive  pe* 
riods  of  repose,  between  the  eruptions,  sometimes  extending  to  years, 
and  centuries,  are  among  the  principal  circumstances  which  charac- 
terise volcanos. 

ATTRACTION  AND  REPULSION,  although  less  obvious  than  some  of 
those  phenomena  that  have  been  mentioned,  are  undoubtedly,  more 
important  in  relation  to  the  system  of  things,  than  any  or  all  other 
natural  causes  and  events. 

Gravitation  is  the  bond  which  connects,  equally,  the  greatest  and 
the  minutest  parts  of  our  system.  Every  particle  of  matter  gravi- 
tates towards  every  other ;  every  mass,  however  large,  is  attracted 
by  every  particle  ;  every  member  of  our  system,  and  every  sys- 
tem, in  the  great  system  of  systems  is  affected,  reciprocally,  by 
every  other :  projectile  power,  or  immense  distance  and  counter- 
balancing attractions  keep  them  from  rushing  together  in  ruinous  col- 
lision ;  and  the  whole  creation  of  matter  is  afloat  in  space,  suspend- 
ed and  sustained  by  the  energy  of  almighty  power. 

It  would  be  foreign  to  our  present  purpose,  to  designate  the  de- 
tails of  the  various  kinds  of  attraction — the  gravitating,  the  electri- 
cal, the  cohesive,  the  chemical,  and  the  magnetic. 

The  magnetic  is  universally  known,  and  by  its  aid  we  traverse  the 
ocean  and  pathless  deserts.  It  presents  the  most  striking  and  famil- 
iar example  of  repulsion,  a  power,  which,  springing  from  various 
causes,  and  operating  under  various  forms,  is,  although  unseen,  every 
where  active  around  us.  We  do  not  certainly  know,  that  magne- 
tism can  be  permanently  attached  to  any  other  substances  than  iron 
and  nickel,*  although  we  can  no  longer  entertain  a  doubt,  that  it 
holds  a  permanent  connexion  with  heat,  light  and  electricity. 

Attraction  is  only  a  name  for  an  unknown  cause,  of  which  we  have 
no  other  knowledge  than  that  it  depends  on  the  will  of  God.  Mys- 
terious indeed  It  is,  but  it  is  not  more  so  than  the  connexion  of  our 
intelligent  minds  with  our  living  bodies.  The  Creator  can  endue  mat- 
ter with  any  properties,  and  there  are,  undoubtedly,  many  possible 
qualities,  which  he  has  not  bestowed,  and  many  actual  ones,  which 
we  have  not  discovered. 

ASTRONOMY  examines  the  heavenly  bodies,  and  the  construction  and 
relations  of  the  celestial  systems.  It  has  taught  us  that  the  diffuse  light 
of  the  Galaxy  is  composed  of  the  mingled  effulgence  of  innumerable 
stars,  each  of  which  is,  probably,  the  centre  of  a  system,  and  the  con- 
tinually increasing  power  of  penetrating  into  space,  acquired  by  the 
modern  improvements  of  the  telescope,  evinces,  that  we  have  only 
begun  to  number  the  stars,  and  that  we  shall  never  be  able  to  call 


Some  add  cobalt. 


INTRODUCTION.  1 1 

them  all  by  their  names.  But  we  have  measured  the  distances  and 
the  dimensions  of  the  planets  and  the  periods  and  the  rapidity  of 
their  revolutions  ;  and  we  have  ascertained  their  absolute  and  relative 
weight.  We  know  not  where  discovery  will  stop  ;  the  noble  science 
of  astronomy  is  now  cultivated  with  an  ardor  not  surpassed  even  by 
that  of  the  age  of  Newton,  and  with  means  far  superior.  Innumera- 
ble discoveries  of  new  stars  have  been  made  ;  and  it  is  ascertained, 
that  a  part  of  the  fixed  stars  have  a  revolution  indicating  the  move- 
ments of  the  members  of  particular  systems.  This  is  true,  especial- 
ly of  what  are  called  the  double  stars,  and  the  sublime  conception 
is  entertained,  that  the  whole  stellary  system,  with  its  myriads  of 
planetary  worlds,  revolves  in  the  course  of  ages  around  a  common 
centre. 

Astronomy  is,  not  without  reason,  regarded,  by  mankind,  as  the 
sublimest  of  the  natural  sciences.  Its  objects,  so  frequently  visible, 
and  therefore  familiar,  being  always  remote  and  inaccessible,  do  not 
lose  their  dignity. 

Although  Newton,  a  century  ago,  unfolded  the  structure  of  the 
universe  ;  Herschel,  La  Place,  La  Lande,  and  other  distinguished 
astronomers  have  continued  to  enlarge  our  knowledge  of  the  heavens* 
and  the  Astronomical  Society  of  London  diligently  collects  and  com- 
pares all  discoveries,  while  some  of  its  members  are  ardently  engaged 
in  making  new  observations. 

The  practical  applications  of  astronomy,  in  determining  the  latitude 
and  longitude  especially  at  sea,  are  highly  important ;  the  exact  cal- 
culation and  prediction  of  some  of  its  more  striking  phenomena  have 
removed  the  superstitious  dread  of  eclipses,  and  substituted  a  rational 
comprehension  of  their  cause ;  while  the  transits  of  the  planets  and 
the  measurement  of  arcs  of  great  circles  of  the  heavens  in  different 
latitudes,  have  been  thought  sufficiently  important  to  justify  voyages 
and  journeys  to  the  most  distant  and  inhospitable  regions.  It  may  be 
mentioned  also,  without  impropriety,  that  the  observation  of  the  heaven- 
ly bodies  is  a  rational  source  of  amusement.  In  a  fine  night,  the  teles- 
cope, although  not  like  that  of  Herschel,  of  immoderate  size  and  ex- 
pense, is  an  interesting  companion,  and  we  contemplate  with  delight  the 
mild  lustre  of  the  evening  star,  the  fiery  face  of  Mars,  the  silver  orb  of 
Jupiter,  his  belts  and  his  satellites,  and  the  incomprehensible  rings  of 
Saturn. f 


*  Chalmers,  with  his  own  peculiar  eloquence,  has  arrayed  astronomy  in  new  at- 
tractions, by  connecting  its  physical  features  with  our  moral  instruction. 

t  In  this  connexion  we  ought  not  to  forget  Dollond,  Lerebours,  Fraunhofer  and 
other  distinguished  artists  without  whose  aid  the  science  of  astronomy  must  have 
t>een  arrested  in  its  course. 


12  INTRODUCTION. 

2.  NATURAL  HISTORY  describes  the  external  appearance  or  at 
least  the  distinctive  characters  of  all  natural  bodies.  Its  numerous 
sub-divisions,  are  all  included  under  Zoology,  Mineralogy  and  Botany. 

ZOOLOGY,  which  includes  the  whole  animal  world,  comprehends 
also  a  great  number  of  subdivisions,  e.  g.  ornithology,  ichthyology, 
herpetology,  entomology,  conchology,  &c.  As  it  is  conversant  about 
animated  beings,  it  inquires  also  into  their  habits,  their  food,  their  re- 
production, their  decay  and  their  death.  Strictly,  man  is  at  the  head 
of  this  department  of  Natural  History.  Zoology  begins  with  man 
and  ends  with  the  snail  and  the  oyster  ;  and  in  its  course  it  embraces 
the  elephant  and  the  mouse,  the  lion  and  the  mole,  the  whale  and 
the  minim,  the  eagle  and  the  gnat. 

Among  gigantic  animals,  the  whale,  the  larger  seals,  the  rhinoce- 
ros, the  hippopotamus,  the  wild  buffalo,  the  giraffe,  the  camel  and 
the  elephant,  are  signal  examples,  and  among  the  reptiiia,  the  boa 
constrictor  and  the  anaconda  are  sometimes  of  enormous  size.  In 
zoology,  living  animals  are  of  course  more  interesting  and  more  in- 
structive subjects  of  study  than  dead  ones,  however  wrell  preserved. 

A  menagerie,  is  one  of  the  most  gratifying  kinds  of  museums,  and 
these  exhibitions,  as  regards  especially  the  larger  and  more  perfect 
wild  animals,  afford  very  fine  opportunities  for  the  study  of  zoology. 
The  panthers  and  the  elks  of  America,  the  rein  deer  of  Lapland, 
the  lions,  the  camelopards  and  the  zebras  of  Africa,  and  the  royal 
tigers,  the  hyenas  and  the  elephants  of  Asia,  torn  from  their  native 
forests  and  dens,  are  imprisoned  not  only  in  the  apartments  of  Exe- 
ter 'Change,  of  the  Tower  of  London,  and  of  the  Garden  of  Plants 
of  Paris,  but  in  the  cages  of  the  travelling  caravans  which  have  now 
become  common  in  this  country. 

But,  where  all  opportunities  from  museums,  whether  of  dead  or 
living  animals,  are  wanting,  zoology  may  still  be  studied,  with  good 
advantage,  by  the  aid  of  the  numerous  works  on  this  science,  illus- 
trated as  most  of  them  are  by  accurate  engravings. 

MINERALOGY  AND  GEOLOGY  comprise  all  that  relates  to  the  satehil 
constitution  of  our  planet,  including  its  atmosphere  and  vari©iik» gases, 
as  well  as  its  waters,  its  metals,  its  salts,  its  combustibles,  arftfitEJ  garthy 
combinations.  The  study  embraces  not  only  mountain^  #dd  conti- 
nents, but  the  pebbles  under  our  feet,  the  sand  ofl'M  Chores  and 
the  dust  that  is  borne  on  the  winds.  It  attempts  to  account  for  the 
origin  and  causes  of  the  present  state  of  things,  and  it  contemplates 
the  impending  changes,  decay  and  dissolution  of  the  firm  substratum 
of  our  globe.  Minerals,  although  to  some  extent  constantly  before 
us,  are,  for  the  greater  part,  far  more  inaccessible  than  vegetables 
and  animals.  Many  of  them  are  drawn  from  the  recesses  of  the 
earth,  from  the  caverns  and  mines  remote  from  the  light  of  day. — 
In  this  department  then,  although  something  may  be  done  with  the 


INTRODUCTION.  13 

aids  of  such  things  as  we  can  every  where  obtain,  still,  a  cabinet  or 
museum  is  peculiarly  necessary,  and  as  this  study  is  acknowledged 
to  be  both  important  and  interesting,  collections  in  mineralogy  are 
found  in  colleges  and  universities  more  generally  than  any  other  sub- 
jects of  natural  history.  They  have  the  very  important  advantage 
of  being,  with  few  exceptions,  not  liable  to  destruction,  nor  to  any 
spontaneous  changes.  They  need  no  preparation,  but  when  detach- 
ed from  their  native  situations,  and  reduced  to  a  proper  size,  are 
ready  for  the  museum.  This  department  of  nature  affords  much  of 
the  wealth  of  nations,  many  of  the  comforts  of  civilized  and  polished 
society,  nearly  all  the  instruments  of  physical  and  philosophical  re- 
search, and  most  of  those  of  the  ornamental  and  useful  arts.  Civili- 
zation, social  refinement  and  science  cannot  exist  where  the  mine- 
ral kingdom  is  not  explored  and  understood,  and  especially  where 
iron  and  some  of  the  other  metals  are  not  known  and  used. 

Although  no  aliment  for  living  beings  is  obtained  from  this  king- 
dom, very  important  remedies  are  derived  from  it,  especially  from 
several  of  the  earths  and  metals.  Plants  and  animals  are  probably 
more  attractive  to  the  eyes  of  most  persons  than  the  greater  part 
of  minerals  ;  still,  among  crystals  are  found  objects  of  extreme 
beauty,  whose  polish  and  whose  form  rival  the  finest  works  of  art, 
and  some  of  the  gems  have  ever  been  selected  to  adorn  diadems 
and  crowns. 

GEOLOGY,  which  reveals  to  us  the  actual  structure  of  the  globe, 
and  the  natural  position,  relation  and  associations  of  its  productions, 
affords  important  light  in  the  research  for  useful  minerals ;  and  it  ex- 
hibits, in  the  arrangement  and  contrivance  of  the  mineral  strata,  de- 
cisive proofs  of  the  power,  wisdom  and  design  of  its  author. 

BOTANY  is  the  natural  history  of  plants.  It  is  a  beautiful  and  em- 
inently useful  branch  of  knowledge.  It  is  constantly  extending  its  re- 
searches and  adding  new  species  to  the  great  number,*  which  have 
been  already  discovered. 

The  loftiest  forest  tree  and  the  humblest  shrub  are  equally  within 
its  domain,  and  every  climate,  and  every  continent  and  island,  are 
visited  for  the  discovery  of  new  species.  The  plants  that  grow  in 
mountains  indicate,  with  great  accuracy,  the  climates  that  belong  to 
the  different  elevations ;  the  plants  and  fruits  of  tropical  regions  may 
grow  at  the  foot,  and  the  stunted  evergreens  of  the  polar  circle  may 
crown  the  summit. 

In  this  elegant  department  of  knowledge,  a  sufficient  number  of  its 
subjects  is  scattered  every  where  around  us,  to  afford  the  means  of 
comprehending  the  outlines  of  the  science  and  of  prosecuting  it  with 


Fifty-six  thousand,  or  more. 


14  INTRODUCTION. 

considerable  advantage.  Its  dried  specimens  are  preserved  with  in-' 
comparably  more  ease  than  those  of  animals,  and  it  is  thought  to  be  an 
object  worthy  even  of  princely  munificence  to  found  collections  of 
living  plants,  and  to  preserve  them  in  the  Botanical  Gardens,  as  is 
seen  in  the  Royal  establishment  of  Kew  in  England,  and  of  the  Gar- 
den of  Plants  in  Paris.  Even  public  spirited  individuals*  have,  either 
by  their  own  efforts,  or  by  the  assistance  of  private  citizens,  like  them- 
selves, formed  botanical  gardens,  of  signal  beauty  and  utility ;  pre- 
senting in  one  grand  perspective,  the  vegetable  glories  of  the  world. 
The  study  of  the  science  is  thus  facilitated,  in  a  surprising  degree, 
and  the  botanical  student  finds,  within  the  bounds  of  at  most  a  few 
acres,  the  plants,  to  have  seen  which,  in  their  native  soils,  would  have 
demanded  a  life  of  adventure.  The  vegetable  kingdom  affords  most 
of  the  food  of  men  and  animals,  many  medicines,  and  many  materials 
for  the  arts. 

3.  CHEMISTRY. — The  remaining  branch  of  science  relating  to  nat- 
ural bodies,  begins  where  Natural  Philosophy  and  Natural  History 
stop.  As  the  gleanings  of  its  early  history  may  be  found  in  the  pre- 
faces of  the  larger  elementary  works  on  chemistry,  we  shall  here  omit 
the  vague  annals  of  its  infancy,  and  the  delusions  of  its  middle  age. 
.  It  would  exceed  our  limits  to  trace  the  progress  of  chemistry 
from  age  to  age ;  to  unfold  the  delusions  of  ALCHEMY,  whose  ob- 
ject was  to  discover  the  philosopher's  stone,  an  imaginary  substance, 
which,  it  was  supposed,  would  convert  the  baser  metals  into  gold 
and  silver ;  or,  to  speak  of  the  equally  delusive  pursuit,  after  the 
GRAND  CATHOLICON,  or  universal  remedy,  which  was  to  remove  eve- 
ry disease ;  to  avert  death,  and  confer  terrestrial  immortality  upon 
man ;  or  to  mention  the  imaginary  ALCAHEST,  or  universal  solvent;, 
whose  power  it  was  supposed  nothing  could  resist.  The  alchem- 
ist indeed  imagined,  that  these  miraculous  virtues  resided  in  one 
and  the  same  substance,  and  during  the  dark  ages,  most  of  the  cut 
tivators  of  what  was  then  called  chemistry,  smitten  with  the  deli-, 
rium  of  alchemy,  pursued  their  occult  processes,  in  cells  and  caverns, 
remote  from  the  light  of  heaven,  and  wasted  their  days  and  nights, 
their  talents  and  their  fortunes,  in  a  vain  pursuit.  The  alchemist 
however  accumulated  many  valuable  facts,  which  have  been  em- 
ployed, with  good  advantage,  in  laying  the  foundations  of  modern 
chemical  science. 

Some  knowledge  of  chemical  arts  is  coeval  with  the  earliest  stages 
of  human  society,  and  it  has  happened  with  this,  as  with  other  branch- 
es of  natural  knowledge,  that  many  facts  were  discovered,  and  accu- 


*As  was  done  by  Mr.  Roscoe  and  Dr.  Currie  of  Liverpool,  Dr.  Hope  of  Edin- 
burgh, Mr.  Bartram  of  Philadelphia,  and  Dr.  Hosack  of  New  York. 


INTRODUCTION.  15 

mulated,  in  the  practice  of  the  arts,  and  in  domestic  economy,  long 
before  any  general  truths  were  established,  by  a  course  of  inductive 
reasoning,  upon  the  phenomena. 

The  arts  are  all  either  mechanical  or  chemical,  and  not  unfrequent- 
ly  both  are  involved  in  the  same  processes.  The  practices  of  the 
arts  may  be  regarded  as  experiments  in  natural  philosophy  and  chem- 
istry. The  object  of  the  artist  is  usually  gain  ;  but  he,  or  any  other 
person,  who  views  the  facts  correctly,  may  reason  upon  them  advan- 
tageously, and  thus  obtain  important  instruction. 

Glass  is  a  chemical  compound,  usually  of  siliceous  earth  and  fixed 
alkali,  or  in  a  more  extended  view,  of  alkaline,  saline,  metallic  and 
earthy  materials.  These,  after  being  duly  proportioned,  are  com- 
bined by  the  effect  of  fire,  and  various  adventitious  matters  are  added, 
to  impart  color  or  to  discharge  it,  to  increase  the  density,  or  to  dimm- 
ish the  hardness,  or  for  various  other  purposes. 

The  production  of  the  materials  of  the  glass  depends  therefore 
upon  chemical  principles,  and  is  thus  far,  a  chemical  art.  But,  the 
fabrication  of  the  vessels  depends  upon  mechanical  causes,  principally 
the  breath  of  the  artist,  injected  through  an  iron  tube,  to  which  the 
melted  glass  is  made  to  adhere.  The  subsequent  cutting,  grinding, 
and  polishing  of  the  glass  are  also  mechanical,  and  thus  glass  is  a 
production  both  of  chemistry  and  mechanism. 

Soap,  (except  the  mere  act  of  mingling  the  oil  and  the  alkali,)  is  a 
production  of  chemistry  alone ;  a  watch  is  a  result  of  mechanism,  but 
the  metals  of  which  it  is  made  are  prepared  by  chemistry  and  me- 
chanism united ;  wool  is  carded,  spun,  woven,  fulled  and  sheared  by 
mechanical  means,  but  it  is  scoured  and  dyed  by  chemical  processes, 
and  thus  through  a  multitude  of  instances,  the  purposes  of  society  are 
accomplished,  by  the  application  of  the  principles  of  one  or  of  the 
other,  or  of  both  of  these  sciences. 

The  science  of  chemistry  considered  as  a  collection  of  elementary 
truths  derived  from  the  study  of  facts,  can  scarcely  be  referred  to  a  pe- 
riod much  beyond  the  commencement  of  the  last  century,  and  its  prin- 
cipal triumphs  have  been  achieved,  since  the  middle  of  that  period. 
It  would  be  premature,  to  detail,  on  the  present  occasion,  the  partic- 
ular discoveries,  which,  like  stars,  rising  successively,  above  the  hor- 
izon, have  broken  forth  in  rapid  succession.  Those  discoveries,  their 
periods  and  authors  will  be  mentioned,  in  giving  the  history  of  each 
particular  substance.  At  present,  it  would  not  be  proper  to  attempt 
any  thing  more  than  to  convey  to  those  to  whom  the  subject  may  be 
new,  a  general  conception  of  the  nature,  extent  and  objects  of  the 
science  of  chemistry,  reserving  the  details  for  the  time  when  they 
will  be  both  the  most  intelligible  and  the  most  interesting.  > 


16  INTRODUCTION. 

DEFINITION.* — CHEMISTRY  is  THAT  SCIENCE  WHICH  INVESTI- 
GATES THE  COMPOSITION  OF  ALL  BODIES,  AND  THE  LAWS  BY  WHICH 
IT  IS  GOVERNED. 

Remark. — This,  of  course,  includes  every  possible  combination 
and  decomposition. 

Chemistry,  taking  into  view  the  properties  discovered  by  Natural 
Philosophy,  begins  its  appropriate  work  where  the  sister  science  stops. 

The  distinction  between  chemistry  and  natural  philosophy  is  illus- 
trated by  the  familiar  examples  of 

1.  Water, 

2.  The  atmosphere, 

3.  Gunpowder. 

Thus,  water  is  composed  of  the  bases  of  two  gases ;  the  air  of  at 
least  two,  and  gunpowder  of  combustible  and  metallic  matter  and  the 
ponderable  part  of  gases. 

Natural  History,  Natural  Philosophy  and  Chemistry  are  all  ne- 
cessary to  complete  the  scientific  history  of  any  thing. 

Natural  History  explains  the  external  appearance  of  bodies ; 

Natural  Philosophy  the  mechanical  properties ; 

Chemistry  the  constitution. 

This  general  position  is  easily  illustrated  by  reference  to  amber, 
tool,  calc-spar,  fossil  salt,  and  other  familiar  bodies. 

Chemistry  is  distinguished  as  an  art  or  a  collection  of  arts,  from 
chemistry  as  a  science :  the  former  is  empirical,  the  latter  is  guided 
by  established  principles,  and  they  are  now,  in  numerous  instances, 
happily  united,  in  the  hands  of  both  practical  and  scientific  men. 

Chemical  arts  are  numerous ;  glass  and  soap-making,  have  been 
already  mentioned,  and  pottery,  metallurgy,  and  dyeing,  may  be  ad- 
ded ;  the  latter  depends  on  the  affinity  of  coloring  matter  for  fibre, 
or  for  the  mordant,  or  for  both. 

The  vinous  fermentation  produces  cider,  wine,  perry,  bear,  me- 
theglin,  &ic.  Carbonic  acid  gas  is  evolved,  while  alcohol  is  formed, 
and  the  rapidity  of  the  process  depends  on  the  temperature. 

Leather,  is  formed  from  skins  and  tannin  contained  in  the  astrin- 
gent vegetables;  the  tannin  of  the  latter  uniting  with  the  gelatine  of 
the  skin. 

Bread,  is  produced  by  a  peculiar  fermentation :  its  sourness,  ow- 
ing to  excessive  fermentation,  is  corrected  by  an  alkali  and  the  carbon- 
ic acid  which  is  evolved,  renders  it  lighter  than  before. 


*  For  various  definitions  the  student  may  see  the  principal  authors,  Thomson. 
Fourcroy,  Henry,  Murray,  La  Grange,  Thenard,  Davy,  Brande,  Turner,  Hare  and 
others. 


INTRODUCTION.  ]  7 

Ink ;  the  theory  of  its  formation  is,  that  the  astringent  principl& 
unites  with  the  oxide  of  iron,  and  gum  Arabic  or  sugar  suspends  the 
precipitate. 

The  burning  of  lime  consists  in  the  expulsion  of  the  carbonic  acid, 
by  heat ;  the  acid  gas  forms  nearly  one  half  of  the  weight  of  the 
limestone,  marble,  and  chalk. 

Art  and  science  mutually  aid  each  other,  because  art  furnishes 
hands  and  science  eyes  ;  science  without  art  is  inefficient ;  art  with- 
out science  is  blind. 

The  philosophical  chemist  must  understand  the  principles  of  the 
chemical  arts,  and  the  more  of  the  practice  he  knows  the  better. 

Chemical  artists  should  understand  the  science,  at  least  of  their  own 
arts,  and  practical  knowledge  is  of-  course  indispensable. 

Not  satisfied  with  the  knowledge  of  the  external  properties  and  the 
mechanical  relations,  which  are  unfolded  by  Natural  History  and  by 
Physics,  but  taking  them  into  view,  and  retaining  and  using  their 
principal  discoveries,  chemistry  proceeds  to  investigate  the  hidden 
constitution  of  every  species  of  material  existence,  in  earth,  sea  and 
air. 

Earth,  air,  fire  and  water,  were  the  four  elements  of  the  ancient 
school.  They  have  however,  yielded  to  analysis,  and  water,  bland 
and  simple  as  it  seems,  contains  two  bodies,  whose  properties,  are  en- 
tirely different  from  its  own  and  from  those  of  each  other ;  burning, 
when  mingled  and  ignited  in  large  quantities,  with  violent  explo- 
sion ;  and  in  a  small  stream,  with  a  heat,  which  melts  and  dissipates 
the  firmest  substances.  We  should  never  have  conjectured  that 
water,  whose  great  prerogative  it  is,  to  extinguish  fire,  contains 
both  a  combustible  and  a  supporter  of  combustion. 

The  air,  the  pabulum  of  life  to  the  whole  animal  and  vegetable 
creation,  mild  and  negative  like  water,  is  not  simple  but  contains  inci- 
dentally many  bodies, — essentially  however  only  two ;  one  of  which 
and  that,  constituting  four  fifths  of  the  whole,  is,  and  was  intended  to 
be,  in  a  high  degree  noxious  and  even  deadly  to  animal  life  and  fatal 
to  combustion.  The  air  does  not  destroy  life  instead  of  invigorating 
our  frames,  and  extinguish  instead  of  inflaming  combustion,  because 
the  prevalent  noxious  principle  of  the  air  (nitrogen)  is  balanced  by  a 
life  and  fire-sustaining  principle  (oxygen)  too  vigorous  to  be  trusted 
alone,  and  therefore,  diluted  exactly  to  the  proper  degree,  by  the  op- 
posite principle,  both  being,  by  another  extraordinary  provision,  sus- 
tained, in  constant  proportion,  and  thus  producing  a  salubrious  and 
unchanging  atmosphere. 

The  earth,  under  our  feet,  the  soil,  the  sand,  the  gravel,  the  firm 
substance  of  the  rocks,  is  not  simple.  In  this  ancient  but  assumed 
element,  we  have  a  double  complexness.  The  one  imagined,  simple 


18  INTRODUCTION. 

earth  contains  at  least  nine,  and  each  of  these  is  again  complex,  con- 
taining for  one  principle,  oxygen,  the  same  that  exists  both  in  wa- 
ter and  in  the  atmosphere,  united  to  nine  or  ten  varieties  of  met- 
als or  combustibles  none  of  which  are  known  in  common  life. 

He  who  is  acquainted  with  the  wonderful  effects  of  chemical  com- 
bination, will  not  think  it  strange  that  half  the  weight  of  marble  is 
carbonic  acid,  and  that  metals,  when  combined  with  oxygen,  resemble, 
very  exactly,  the  earthy  substances. 

Light  as  well  as  heat,  is  contained  in  common  fire,  and  therefore 
it  is  not  simple,  unless  fire  and  heat  are  varieties  of  one  and  the  same 
thing. 

Modern  research  has  proved  that,  besides  light,  which  in  its 
seven  prismatic  colors,  is  contained  in  the  solar  beam,  there  is  also, 
in  this  emanation,  an  opake,  radiant  principle,  which  accompanying 
light  and  heat,  neither  warms  nor  illuminates,  but  acts  to  decompose 
certain  chemical  compounds ;  that  there  are  opake  rays  which  warm 
but  do  not  illuminate,  and  illuminating  rays  which  are  cold  to  the 
sense  of  living  animals,  but  impart  to  the  universe  its  splendid  drape- 
ry of  colors ;  and  that,  associated  with  one  or  more  -of  these  emana- 
tions, there  is  a  surprising  power,  which  imparts  magnetism  to  a  needle, 
and  gives  it  the  properties  of  the  loadstone.  But  we  have  used  the 
word  element  without  defining  it. 

An  element  is  an  undecomposable  body — it  is  therefore  simple,  or 
in  other  words  not  reducible  to  any  other  form  of  existence.  We 
must  however,  carefully  distinguish,  between  real  elements,  and  those 
which  are  such,  only  in  relation  to  the  present  state  of  our  knowledge. 
When  modern  science  speaks  of  a  body  as  elementary,  it  intends 
nothing  more,  than  that  it  has  not  been  decomposed.  It  is  therefore 
simple  as  far  as  we  know,  but  it  is  possible  that,  by  future  efforts,  it 
may  be  decomposed.  Although  we  have  no  reason  to  doubt,  that 
there  are  real  elements,  we  cannot  say,  that  we  are  certainly  in  pos- 
session of  any  one  element.  It  is,  however,  perfectly  safe  to 
reason  upon  bodies  as  elementary,  until  they  are  proved  to  be 
compound.  Iron  is,  as  far  as  we  know,  a  simple  body ;  we  cannot 
as  yet,  exhibit  it  In  any  simpler  form ;  all  we  can  do,  is  to  alter 
its  figure  and  size,  without  at  all  changing  its  nature.  But  iron 
rust,  or  the  scales  which  fly  off,  when  red  hot  iron  is  hammered,  are 
not  simple  ;  they  consist  of  iron,  combined  with  oxygen,  one  of  the 
principles  of  the  atmosphere  ;  we  can  exhibit  these  substances  in  a 
simpler  form;  the  iron,  which  they  contain  can  be  separated  from 
the  aerial  principle,  and  both  can  be  exhibited  apart,  and  thus  the 
proof  will  be  complete  ;  red  lead  and  red  precipitate  are  still  better 
examples,  because  the  former  can  be  partially,  and  the  latter  wholly, 
brought  back  to  the  condition  of  metals,  by  simply  heating  them. 


INTRODUCTION.  19 

The  four  ancient  elements,  earth,  air,  fire  and  water,  were  assum- 
ed at  hazard,  because  they  are  so  conspicuous  and  important ;  the 
conception  was  grand  but  it  was  wholly  erroneous. 

Instead  of  four  elements,  we  have  at  the  present  time  not  less 
than  fifty,  nearly  four  fifths  of  which  are  metals  ;  the  remainder 
are  chiefly  combustibles,  and  bodies,  which,  combining  with  com- 
bustibles and  metals  with  peculiar  energy,  are  generally  called  support- 
ers of  combustion.* 

Our  simple  bodies  then  are 

1.  Metals,  about  40f 

2.  Combustibles  not  metallic,  7-j- 

3.  Principles  or  supporters  of  combustion,  2  or  3 

4.  One  body,  or  possibly  two {  of  an  undetermined  char- 
acter; in  all  50  or  51 

5.  Imponderable  bodies,  light,  heat  and  electricity;  besides  the 
power  called  magnetism  and  the  other  varieties  of  attraction. 

The  principal  object  of  chemistry  is  to  display  first,  the  great 
powers  upon  which  its  phenomena  depend  ;  and  secondly,  the  proper- 
ties of  the  elements,  the  mode  and  energy  of  their  action,  the  combi- 
nations which  they  are  capable  of  forming,  the  properties  of  the  result- 
ing compounds,  and  the  laws  by  which  they  are  governed.  This 
statement,  obviously,  includes  all  bodies  natural  and  artificial.  There 
are  many  chemical  compounds  made  by  art,  which,  as  far  as  we  are 
informed,  do  not  exist  in  nature,  and  there  are  many  natural  bodies 
which  art  has  not  yet  been  able  to  imitate. 

The  philosophical  chemist  studies  both  the  properties  of  the  ele- 
ments, and  the  constitution  of  the  intermediate  or  proximate  com- 
pounds of  the  whole  material  world,  as  far  as  it  is  tangible  by  man. 
Of  the  chemical  constitution  of  the  planetary  and  stellary  bodies,  we 
have  no  knowledge,  except  from  the  hints  that  are  afforded  by  the 
occasional  projection  to  our  earth,  of  stony  masses,  severed  by  ex- 
plosion from  luminous  meteors  or  fire  balls,  which  occasionally  pass, 
with  great  velocity,  through  our  atmosphere. 

It  will  be  easily  understood,  that  the  philosophical  chemist  under- 
takes an  arduous  and  responsible  duty,  involving  much  manual  skill 
and  labor  and  mental  effort,  but  the  reward  is  rich  and  gratifying. 


*  Some  object  to  this  phrase,  preferring  to  consider  combustion  as  being  only  an  ex- 
ample of  intense  chemical  action ;  this  view  is  philosophical ;  but  combustion  is  so  fre- 
quent an  occurrence  and  involves  so  many  imporant  chemical  events,  that  it  is  con- 
venient, in  accordance  with  the  general  practice  of  mankind,  to  designate  it  and 
the  bodies  concerned  in  it,  by  a  peculiar  phraseology. 

t  It  is  perhaps  doubtful  where  some  of  these  bodies  ought  to  be  classed — whether 
among  metals,  or  combustibles. 

t  Perhaps  silicon  and  bromine ;  we  have  however  classed  them  where  they  ap- 
pear to  belong. 


20  INTRODUCTION. 

The  veil  is  withdrawn  from  the  face  of  nature,  and  a  constitution 
of  things,  not  at  all  suspected  by  those  ignorant  of  chemistry,  is  un- 
folded. 

The  pupil  in  this  science  discovers  that  he  has,  all  his  life,  walked 
unconsciously  amidst  powerful,  although  unseen  energies  ;  that  like  a 
child  scattering  sparks  among  gun-powder,  he  has  often  heen  sport- 
ing with  dangerous  elements,  and  that,  with  all  his  curiosity  and  in- 
telligence, he  has  known  only  the  surface  of  things.  He  finds,  eve- 
ry where,  innumerable  applications  of  his  knowledge  to  purposes  of 
practical  utility,  to  those  of  domestic  life,  to  the  arts  which  enrich 
and  adorn  society,  and  to  the  illustration  of  the  wisdom,  power  and 
goodness  of  that  great  being,  whose  pleasure  called  the  physical  uni- 
verse into  existence  and  constantly  sustains  it  in  order  and  beauty. 

To  exhibit  the  proof  of  these  statements,  even  in  outline,  would 
require  a  distinct  recital,  and  might  well  occupy  a  treatise ; — but  op- 
portunities will  occur  in  the  progress  of  this  work,  when  these  truths 
may  be,  to  a  certain  degree,  illustrated. 

It  would  be  premature,  to  attempt,  at  this  time,  to  exhibit  the  na- 
ture of  the  evidence  upon  which  chemical  deductions  are  founded, 
and  the  mode  in  which  the  study  and  exhibition  of  the  science  are 
prosecuted. 

It  is  sufficient  to  say,  that  like  the  other  physical  sciences,  chemis- 
try derives  its  evidence,  from  experiment,  and  the  observation  of.  facts  ; 
but,  as  a  great  proportion  of  the  facts  are  such  as  do  not  occur  in 
common  life,  and  still,  as  they  all  have  their  foundation  in  the  consti- 
tution of  things,  it  becomes  necessary  for  the  philosophical  chemist 
to  perform  a  great  number  of  experiments  ;  in  other  words  to  exhibit 
numerous  facts  ;  for,  an  experiment  is  nothing  but  the  exhibition  of  a 
fact,  happening  according  to  natural  laws,  which  it  is  not  in  our  power 
either  to  create,  to  cancel  or  to  modify.  Hence,  the  necessity  of  be- 
coming well  acquainted  with  those  laws.  Whenever  all  of  them 
shall  be  fully  understood,  then  chemistry  will  have  reached  its  perfec- 
tion, and  in  relation  to  the  science,  the  greatest  service  which  we  can 
perform,  is  to  extend  and  perfect  its  general  laws.  At  some  future 
day,  it  will  not  be  necessary  to  study  facts  so  much  in  detail  as  now : 
selections  will  be  made  to  illustrate  general  principles,  and  thus  chem- 
istry will  be  assimilated  to  natural  philosophy. 

Chemistry  may  be  regarded  in  three  views,  all  of  which  are  inter- 
esting and  important. 

1 .  As  a  branch  of  general  philosophy. 

2.  As  a  school  for  the  chemical  arts  and  for  many  of  those  of  do*- 
rnestic  economy. 

3.  As  an  important  auxiliary  to  the  profession  of  medicine  and  to 
pharmacy. 


INTRODUCTION.  21 

In  accordance  with  all  these  views,  it  is  now  ardently  and  perse- 
veringly  cultivated,  in  every  enlightened  country.  In  every  university 
and  medical  school ;  in  every  college ;  in  many  academies ;  in  volunta- 
ry associations,  in  larger  and  smaller  towns,  supporting  Lyceums*  and 
Athenaeums  ;*  in  popular  courses  of  lectures,  sustained  by  private  indi- 
viduals ;  and  even  in  manufacturing  establishments,  fostered  by  the 
zeal  of  the  operative  artizans ;  chemistry,  with  the  sister  sciences, 
natural  philosophy  and  natural  history,  is  assiduously  and  advantage- 
ously cultivated.  It  would  in  this  age,  be  as  disreputable  for  any  per- 
son, claiming  to  have  received  a  liberal  education,  or  to  possess  liberal 
knowledge,  to  be  ignorant  of  the  great  principles  and  the  leading 
facts  of  chemical  as  of  mechanical  philosophy.  Many  intelligent 
artizans  now  resort  to  philosophical  lecture  rooms,  to  learn  more  per- 
fectly the  principles  of  their  respective  arts ;  and  the  great  familiarity 
with  the  practical  facts  of  their  callings  which  they,  of  course  pos- 
sess, and  ordinarily  in  a  degree  superior  to  that  attained  by  teachers- 
of  science,  enables  them  to  apply  with  great  advantage  the  general 
principles  which  they  acquire. 

Domestic  economy  is  greatly  benefitted  by  a  correct  knowledge 
of  the  principles  of  natural  science  and  especially  of  chemistry. 
Besides  the  instances  that  have  been  already  named — the  combus- 
tion of  fuel ;  the  equal  and  economical  distribution  of  heat  and 
light ;  the  preservation  of  delicate  fruits  and  of  their  extracts  or 
jellies ;  the  preparation  of  food  by  steaming,  boiling  and  roasting ; 
the  extraction  of  animal  gelatine ;  the  manufacture  of  starch ;  the 
separation  of  butter  and  cheese  from  the  milk ;  the  bleaching  and 
dyeing  of  stuffs  and  many  more  domestic  arts  depend  upon  the  prin- 
ciples of  science,  and  chiefly  upon  those  of  chemistry.  It  is  true 
that  these  things  are  accomplished,  with  more  or  less  skill,  by  per- 
sons unacquainted  with  science,  but  they  would  be  better  and  more 
effectually  done,  were  the  artists  enlightened  more  generally  in  its 
principles.  To  insist  on  no  other  instance,  there  is  no  doubt  that 
in  the  common  modes  of  using  fuel,  a  large  part  is  wasted,  and  that 
part  skilfully  applied  would  be  more  effectual  than  the  whole,  as  it  is 
in  most  cases  actually  used. 

There  is  now,  generally,  but  one  opinion  as  to  the  importance  of 
chemical  science  to  the  profession  of  medicine.  This  opinion  is 
sufficiently  evinced  by  the  fact,  that  there  is  no  medical  school  in 
which  chemistry  is  not  taught,  nor  any  medical  examination  in  which 
this  topic  is  omitted.  It  is  true  that  medicine  may  be  practised,  em- 
pirically, by  those  who  understand  neither  the  structure- of  the  human 
frame,  nor  the  nature  and  properties  of  the  substances,  which  they 

*  Popular  names  in  this  country  for  certain  institutions  having  for  their  object,  the 
dissemination  of  useful  knowledge. 


22  INTRODUCTION. 

administer.  But  who  would  choose  to  trust  such  men ;  or  those, 
who,  equally  uninformed,  as  to  the  nature  of  things,  mix,  compound 
and  vend,  by  precept  and  example  alone  ?  Both  may  indeed  do  it, 
to  a  certain  extent,  successfully,  but  it  is  travelling  blindfold,  and,  at 
the  same  time,  leading  others.  Medicine  and  pharmacy  both  need 
the  aid  of  scientific  chemistry ;  then  they  can  proceed  with  intelli- 
gence and  confidence — they  can  shun  and  rectify  errors,  discard 
abuses,  and  add  new  resources  to  the  healing  art.  They  will  avoid 
mixing  inconsistent  and  mutually  subversive  ingredients  ; — they  will 
reject  the  spurious  and  inert — scrutinize,  w^ith  skill  and  knowledge, 
the  genuineness  of  medicines,  and  avoid  painful — sometimes  fatal 
mistakes. 

The  principles  of  natural  and  experimental  philosophy  as  well 
as  of  chemistry,  should  enter  into  the  education  of  a  medical  man ; 
and  if  he  has  not  been  already  initiated  into  these  elements,  he 
should  neglect  no  favorable  opportunity  of  acquiring  them.  They 
are  constantly  brought  into  view,  along  with  the  principle  of  life,  in 
reasoning  upon  the  phenomena  of  the  human  frame ;  and  in  surgery, 
a  correct  knowledge  of  mechanical  principles  is  of  the  utmost  import- 
ance. A  knowledge  of  natural  philosophy  should  every  where  be — 
and  in  some  seminaries  it  is — an  indispensable  qualification  for  medi- 
cal privileges  and  honors. 

The  enlightened  medical  man  will  regard  his  profession  in  a  high- 
er view,  than  as  being  merely  a  business,  by  which  he  may  live. 
The  true  physician  is  a  man  of  extensive  scientific  acquirements. 
No  other  profession  demands  so  much  scientific  knowledge ;  and 
when  this  is  possessed,  by  a  man  of  powerful  and  ardent  mind,  and 
united  to  habits  of  persevering  and  industrious  exertion,  the  medical 
man  may  become  entitled  to  a  distinguished  rank  among  philoso- 
phers. Probably,  science  is  more  indebted  to  medical  men  than  to 
those  of  any  other  profession.  Every  young  man,  who,  with  com- 
petent talents,  enters  upon  the  study  of  this  profession,  should  aim  at 
acquiring  enlarged  views  of  general  as  well  as  of  medical  science, 
and  should  endeavor  to  add  something  to  the  common  stock  of  know- 
ledge. 

The  physician,  who  possesses  the  true  spirit  of  his  profession,  will 
aim  at  a  still  higher  excellence,  that  of  being  a  good  man.  Familiar 
in  the  confidence  of  families,  having  access  to  all,  in  the  hour  of  sor- 
row, and  of  tenderness,  and  weakness,  he  is,  if  virtuous  and  amiable, 
regarded  as  the  common  friend  of  mankind.  It  is  however  in  his 
power,  to  sow  moral  contagion,  or  to  diffuse  the  happiest  influence. 
In  concluding,  we  may  observe  for  the  sake  of  the  general  stu- 
dent, that, 

LITERATURE  adorns  and  illustrates  science,  adding  much  to  its 
attractions,  and  to  the  method,  perspicuity,  and  effect  of  its  communi- 


INTRODUCTION.  23 

cations.  It  cannot  be  entirely  neglected,  by  any  one  who  would 
claim  an  elevated  rank  in  physical  science.  The  accounts  of  the 
most  valuable  researches  and  discoveries  are,  to  a  degree  disgraced, 
by  being  clothed  in  a  coarse  and  slovenly  style,  and  communicated 
without  good  arrangement,  and  without  logical  clearness  and  pre- 
cision. It  sometimes  happens,  that  able  philosophers  and  mathe- 
maticians are  accomplished  scholars,  and  then  the  utmost  finish  is 
given  to  the  solid  structures  of  physical  science. 

No  one  who  has  had  opportunity  to  appreciate  their  attractions, 
and  their  utility,  can  be  insensible  to  the  advantages  and  pleasures  of 
polite  literature,  and  of  miscellaneous  knowledge  presenting  as  they 
do,  a  rich  field  for  investigation,  and  affording  to  the  student,  ample 
remuneration. 

But — ars  longa,  vita  brevis,  meets  us  at  every  turn ;  and,  although 
the  general  student,  in  the  regular  progress  of  a  university  education 
is  of  course,  made  acquainted  with  the  outlines  of  the  principal 
branches  of  human  knowledge ;  in  after  life,  we  are  obliged  to  say, 
non  omnes  omnia  possumus,  while  reluctantly  giving  up  the  rest,  we 
select  and  pursue  some  one  art,  science,  or  practical  profession. 

But  our  previous  efforts  are  not  lost  ;  the  commune  vinculum 
which  connects  all  the  departments  of  human  knowledge,  still  re- 
mains unbroken ;  the  intellect  which  has  been  enriched  by  the  ele- 
ments of  science  and  literature,  continues  to  shed  a  portion  of  their 
lustre  over  its  own  particular  pursuit,  and  occasionally  to  aid,  by  use- 
ful suggestions  and  partial  efforts,  those  who  are  travelling  upon  some 
other  route. 

Knowledge  is  said  to  be  power  ;  it  is  indeed,  power  of  the  most 
comprehensive  and  efficient  kind. 

Knowledge  is  nothing  but  the  just  and  full  comprehension  of  the 
real  nature  of  things,  physical,  intellectual,  and  moral ;  it  is  co-ex- 
tensive with  the  universe  of  being ;  reaching  back  to  the  dawn  of 
time,  and  forward  to  its  consummation. 

It  is  inseparable  from  the  incomprehensible  existence  of  the  creator, 
who  alone  intuitively  sees  the  whole.  Human  life  is  sufficient  for  the 
acquisition  of  only  a  very  small  part  of  universal  knowledge,  and  the 
greatest  and  the  most  enlightened  mind,  measuring  its  acquirements 
by  this  standard,  will  find  no  cause  for  pride. 

It  is  useful  when  we  are  about  entering  on  the  study  of  a 
particular  science,  and  especially  of  one  of  so  great  extent  and 
interest  as  chemistry,  to  remember  that  there  are  many  other  inter- 
esting and  useful  branches  of  knowledge,  and  that  we  always  assume 
too  much,  if  we  claim  all  importance  and  every  attraction,  for  a  par- 
ticular pursuit.  This  is  necessarily  the  feeling  of  every  one  who 
insulates  himself  within  his  own  peculiar  dominion ;  but  he  who  takes 
a  comprehensive  survey  of  human  knowledge,  will  learn  to  appre- 


24  INTRODUCTION. 

ciate  justly  his  own  acquisitions,  and  to  concede  to  others  the  favor 

which  he  would  claim  for  himself. 

#•*•#•  *  *•  #•  * 

Probably  the  greatest  step  that  has  been  made  in  chemical  science 
since  the  discovery  of  oxygen  and  chlorine,  is  in  the  establishment 
of  the  doctrine  of  definite  proportions,  depending  on  the  combina- 
tion of  the  elements  and  of  the  proximate  principles  in  certain  fixed 
ratios, — thus  unexpectedly,  giving  to  chemistry  a  mathematical  basis. 


PART  I.  IMPONDERABLE  AGENTS. 

Sec.  I.  LIGHT. 
"  LIGHT  is  THE  AGENT  OF  VISION." 

The  history  of  its  mechanical  affections  belongs  to  Optics,  but  some 
general  facts  may  be  advantageously  stated  here. 

1.  ITS  MATERIALITY. — By  some  it  is  supposed  to  result  from 
the  vibration  of  subtile  elastic  media  ;  but  every  thing  goes  to  counte- 
nance the  idea  of  its  materiality,  and  this  was  admitted  by  Newton.* 

It  cannot  be  weighed,  because  our  balances  and  organs  of  sense 
are  not  sufficiently  delicate. 

2.  ITS  VELOCITY  is  two  hundred  thousand^  miles  in  a  second  ;  it 
is  seven  or  eight  minutes  in  coming  from  the  sun,  and  were  its  weight 
the   million-millionth,  or  billionth  part  of  a  grain,  it  would,  by  its 
impetus,  destroy  the  firmest  bodies.     Nine  millions  of  particles  of  that 
size  would  not  affect  our  most  delicate  balances.  J — Thorn. 

Momentum,  being  made  up  of  velocity  and  quantity  of  matter,  it 
results,  that  any  degree  of  momentum  may  be  produced  by  increas- 
ing either  the  quantity  of  matter,  or  the  velocity ;  it  therefore  follows 
that  the  particles  of  light  must  be  inconceivably  small. 

3.  Its  velocity  is  progressive,  and  has  been   measured,  by  ob- 
serving the  eclipses  of  Jupiter's  satellites,  when  the  primary  is  nearest 

Dr.  U re  has  given  a  different  view  of  this  subject. — Diet.  3d  Ed.  p.  563. 

I  One  hundred  and  ninety-five  thousand. — L.   U.  K. 

\  "  The  materiality  of  Light  is  sufficiently  proved.  Its  motion,  though  inconceiv- 
ably rapid,  is  progressive,  and  may  be  measured  ;  it  may  be  stopped  in  its  progress, 
or  its  direction  may  be  changed ;  it  may  be  condensed  into  a  smaller,  or  dispersed 
over  a  larger  space  ;  it  is  inflected  when  passing  near  to  any  body,  which  proves  it 
to  be  subject  to  gravitation ;  it  produces  chemical  changes  in  many  bodies,  exists  in 
them  in  a  state  of  combination,  and  is  disengaged  by  the  exertion  of  new  affinities, 
when  it  appears  in  its  original  form." 

"  There  is  no  physical  point  (says  Melville,)  in  the  visible  horizon,  which 
does  not  send  rays  to  every  other  point ;  no  star  in  the  heavens  which  does  not 
send  light  to  every  other  star.  The  whole  horizon  is  filled  with  rays  from  every 
point  in  it,  and  the  whole  visible  universe  with  a  sphere  of  rays  from  every  star.  In 
short,  for  any  thing  we  know,  there  are  rays  of  light  joining  every  two  physical 
points  in  the  universe,  and  that  in  contrary  directions,  except  where  opake  bodies 
intervene."  A  ray  of  light,  coming  from  any  of  the  fixed  stars  to  the  human  eye, 
•'  has  to  pass,  in  every  part  of  the  intermediate  space  between  the  point  from  which 
it  has  been  projected,  and  our  solar  system,  through  rays  of  light  flowing  in  all 
directions,  from  every  fixed  star  in  the  universe  ;  and  in  reaching  this  earth,  it  has 
passed  across  the  whole  ocean  of  the  solar  light,  and  that  light  which  is  emitted  from 
the  planets,  satellites  and  comets.  Yet  in  this  course  its  progress  has  not  been  in- 
terrupted."— Mur. 

4 


26  LIGHT. 

to  and  farthest  from  the  earth.  Seven  minutes  are  now  allowed  by 
calculation,  for  the  passage  of  light  from  the  sun  to  the  earth,  and 
one  twenty  fourth  of  a  second  for  its  passage,  from  pole  to  pole,  of  our 
earth. — L.  u.  K. 

A  body  cannot  be  seen  through  a  bent  tube,  except  by  reflection,  and 
the  shadows  of  bodies  are  exact  copies  of  the  form  of  the  original. 

4.  It  moves  in  right  lines  ;  never  in  curves ;  if  turned,  it  is  always 
at  an  angle. 

5.  Its  rays  are  mutually  repellent,  as  they  always  diverge,*  if  mov- 
ing uncontrolled ;  as  observed  when  they  are  let  into  a  darkened 
room,  through  a  hole  in  the  shutter — especially  when  the  dust  is 
raised  in  the  room,  so  as  to  render  the  progress  of  the  rays  visible. 

6.  IT    OBEYS    THE    LAWS    OF    ATTRACTION. 

It  is  refracted  in  passing  from  one  transparent  medium  into  an- 
other ;  going  obliquely  from  a  denser  into  a  rarer  medium — the  re- 
fraction is  always  from  the  perpendicular,  and  vice  versa  ;  there  is  a 
constant  ratio  between  the  sine  of  the  angle  of  incidence,  and  that  of 
refraction. 

A  piece  of  money  being  placed  in  a  bowl,  and  the  eye  so  situated 
as  just  to  lose  sight  of  it,  is  rendered  visible  by  pouring  in  water. 

A  stick,  standing  out  of  transparent  water,  appears  bent  at  the 
surface. 

A  river,  or  other  transparent  water,  is  deeper  than  it  appears  to 
be,  because  the  image  of  the  bottom  appears  too  high. 

7.  The  amount  of  refraction  is  proportioned  directly  to  the  density 
of  the  body. 

Inflammable  bodies  refract  in  a  higher  ratio,  and  of  course,  inflam- 
mable gases  refract  more  than  those  that  are  not.     At  32°  Fahr.  and 
pressure  30,  the  refractive  power  of  the  following  gases  is  as  follows ; 
Atmospheric  air,  .00000 

Carbonic  Acid,  .00476 

Azotic  Gas,  .03408 

Muriatic  Gas,  -         -  .19625 

Oxygen  Gas,  .86161 

Sub-carburetted  hydrogen  gas,  -        2.09270 

Ammonia,  2.16851 

Hydrogen  Gas,  -        6.61436f 

In  general,  the  refractive  power  increases  with  the  density  of  the 
body ;  but  inflammable  bodies,  hydrogen,  phosphorus,  sulphur,  dia- 
mond, bees-wax,  amber,  spirit  of  turpentine,  linseed  oil,  olive  oil, 
camphor,  &c.  have  a  refractive  power,  from  two  to  seven  times 
greater,  in  respect  to  their  density,  than  most  other  substances. 


*  Rays  from  the  sun  and  fixed  stars,  although  divergent,  are  regarded  as  parallel., 
because  the  immense  distance  renders  the  angle  of  divergence  indefinitely  smalk 
t  Henry,  Biot,  Arago. 


LIGHT.  27 

Sir  Isaac  Newton  observed  this  fact  with  respect  to  the  diamond, 
which  he  thought  was  probably  "an  unctuous  substance  coagulated," 
thus  anticipating  the  discovery  of  its  inflammability.* — L.  u.  K. 

8.  Light  suffers  reflection. 

The  angles  of  incidence  and  reflection  are  always  equal,  as  is 
observed  in  a  common  plane  mirror ;  when  two  persons  on  opposite 
sides,  standing  each  at  the  same  angle,  see  each  others  images. 

9.  All  objects  seen  by  refraction  or  reflection  appear  in  the  direc- 
tion of  the  refracted  or  reflected  ray. 

This  is  confirmed  by  constant  experience. 

10.  Light  undergoes  polarization. f 

"  This  name  has  been  given  to  a  property  of  light,  which  causes 
it  often  to  be  divided  into  two  portions,  one  of  which  is  transmitted, 
the  other  reflected  by  the  same  pane  of  glass  :  or  one  portion  sus- 
tains refraction  in  an  ordinary  degree,  the  other  in  an  extraordinary 
degree.  Again,  all  these  properties  are  found  to  be  commutable ; 
so  that  the  portion  of  the  rays  which  is  reflected  in  one  case,  may 
be  transmitted  in  another ;  or  that  which  in  one  case  sustains  the  or- 
dinary refraction,  in  another,  may  undergo  the  extraordinary  refrac- 
tion, and  vice  versa. 

These  phenomena  are  ascribed  to  the  different  positions  assumed 
by  different  sets  of  rays  ;  certain  poles,  which  they  are  supposed 
to  possess,  being  variously  directed  at  different  times,  so  as  to  de- 
termine their  reflection,  or  transmission,  or  the  degree  of  their  refrac- 
tion.'^ This  topic  belongs  to  optics.^ 

11.  Light  produces  little  or  no  heat. 

The  Lunar  focus  has  always  been  said  to  exhibit  no  heat  that  can 
be  indicated  by  the  most  delicate  thermometer  ;  and  that  whether 
the  rays  were  collected  by  a  lens  or  mirror.  No  heat  was  felt  in  the 
pupil  of  Sir  Joseph  Banks'  eye,  from  the  lunar  rays  collected  by 
Parker's  great  burning  lens. 

But  Dr.  Howard,  of  Baltimore,  by  using  his  very  delicate  differ- 
ential thermometer,  filled  with  etherial  vapor,  ||  apparently  found  a 
little  heat  in  the  moon's  rays. 

The  lunar  light  is  composed  of  all  the  seven  colors,  as  is  evident 
in  the  lunar  bow,  and  in  the  lunar  circles. IT 


*  Dr.  Brewster  states  that  realgar,  (red  sulphuret  of  arsenic,)  and  chromate  of  lead, 
exceed  the  diamond  in  refractive  power,  and  all  other  substances  in  dispersive 
power.— PA.  Tr.  1813. 

t  For  an  account  ot  this  curious  property  of  light,  the  reader  is  referred  to  Henry's 
Chemistry,  10th  Edit.  Vol.  I.  p.  154. — Also  Edin.  Enc.  Article  Optics. — Nich.  Jour. 
Vol.  XXIII,  p.  334,  and  94th  Vol.  of  the  Annales  de  Chimie,  Ure's  Diet.  3d  Edit. 
568,  and  Cambridge  Course  of  Mathematics.  t  Hare's  Comp. 

§  All  transparent  crystals  polarize  light,  except  those  whose  primary  form  is  the 
cube  or  regular  octohedron.  Iceland  crystal  (rhomboidal  calc-spar)  is  by  far  the 
most  energetic. 

}1  Am.  Jour.  Vol.  II.  p.  329.        <T  Am.  Jour.  Vol.  XIV,  p.  397. 


28  'LIGHT. 

12.  Light  is  not   simple. — It  is  composed  of  seven  colors,  as 
separated  by  the  triangular  glass  prism,  in  the  following  order. 

300 


Red,     Orange,     Yellow,     Green,     Blue,     Indigo,     Violet.* 
45  27  48  60  40  80 

beginning  with  the  least,  and  ending  with  the  most  refrangible. 

"  Dr.  Wollaston  found  that  when  a  beam  of  light  only  one  twen- 
tieth of  an  inch  broad  is  received  by  the  eye,  at  the  distance  often  feet, 
through  a  clear  prism  of  flint  glass,  only  four  colors  are  seen,  viz  : 
red,  yellowish  green,  blue,  and  violet.  The  different  rays  being  again 
collected  by  a  lens  into  a  focus,  produced  uncolored  light." — H. 

13.  LIGHT  is  CONTAINED  IN  ALL  BODIES. 

It  appears  to  be  both  inherent  in  them,  and  to  enter  them  from 
without. 

(a.)  It  passes  through  some  without  any  sensible  obstruction — 
they  are  therefore  transparent,  as  glass,  air,  rock  crystal,  &ic. 

Other  bodies  partially  arrest  the  light,  and  others  still  allow  a  little 
to  pass,  while  some  stop  it  entirely ;  this  gives  origin  to  the  terms, 
transparent,  semi-transparent,  translucent,  and  opake.  " 

Strictly,  no  visible  body  is  transparent,  and  therefore  aerial  bodies 
are  really  the  only  ones  that  are  perfectly  transparent,  f  and  even  they, 
become  in  a  degree  visible,  in  consequence  of  the  disturbed  refraction 
of  light. 

(b.)  Diversity  of  color  is  produced  by  the  absorption  of  some 
rays  and  the  reflection  of  others. 

White  bodies  reflect  all,  and  black  absorb  all,  or  nearly  all,  with- 
out decomposition;  when  a  body  appears  red,  green,  yellow,  blue, 
&c.  all  other  rays  are  absorbed  and  these  are  reflected.  All  per- 
sons do  not  perceive  colors- — we  may  very  possibly  find  one  such 
person,  or  more,  in  every  considerable  assembly,  and  many  such  in- 
stances might  be  collected.  Harris,  a  shoemaker  at  Allonby  in  Eng- 
land, could  distinguish  only  black  and  white  ;  when  a  child,  he  could 
not  distinguish  the  cherries  on  a  tree  from  the  leaves,  except  by  their 
form  and  size.  Mr.  Scott  could  not  distinguish  green.  Pink  and 
pale  blue  appeared  alike,  and  so  did  red  and  full  green — which  he 
thought  a  good  match ;  several  of  the  relations  had  similar  defects.  J 
A  tailor  repaired  a  black  silk  and  a  blue  coat  with  crimson. f 

*  Quoted  from  Henry,  10th  Edit.  Vol.  I.  p.  156.— Blue  is  not  mentioned  in  as- 
signing the  relative  spaces,  although  it  is  mentioned  in  the  list  of  colors;  other  au- 
thors assign  60  to  blue,  dividing  the  whole  spectrum  into  360. 

t  Except  chlorine,  and  one  or  two  others. 

t  Ph.  Tr.  1777,  and  78,  and  80.— L.  u.  K.  A  gentleman  of  my  acquaintance 
bought  and  wore  a  scarlet  dress  supposing  it  to  be  drab ;  still  he  was  a  good  judge 
of  pictures.  I  have  known  several  such  examples. 


LIGHT.  29 

14.  Light  is  emitted  as  well  as  absorbed  by  bodies. — Bodies  that 
emit  light  are  called  phosphorescent ;  heat  does  not  accompany  this 
luminous  emission. 

(a.)  Solar  phosphori  are  those  which  after  exposure  to  the  sun,  for 
some  time,  emit  light  in  the  dark. — Du  Fay  having  exposed  a  diamond 
to  the  sun  and  immediately  covered  it  with  black  wax,  it  shone  in  the 
dark  at  the  end  of  several  months,  when  the  wax  was  removed. 

"In  1663,  Mr.  Boyle  observed  that  the  diamond  when  slightly 
heated,  rubbed,  or  compressed,  emitted  a  light  almost  equal  to  that 
of  the  glow  worm." — Ure. 

Snow  has  been  supposed  to  be  a  natural  solar  phosphorus,  but  this 
appears  to  be  incorrect ;  for  it  does  not  shine  in  a  perfectly  dark 
place  ;  it  seems  to  operate  merely  by  reflecting  the  light  which  is 
abroad  even  in  the  night,  except  when  the  clouds  are  very  heavy,  in 
the  absence  of  the  moon. 

(b.)   There  are  artificial  solar  phosphori. 

Canton's  preparation. — Sulphuret  of  lime,  made  by  stratifying 
burnt  oyster  shells  and  flowers  of  sulphur,  and  heating  them  in  a  phial, 
or  in  a  crucible  in  a  furnace. 

Bolognian  phosphorus,  viz,  sulphate  of  barytes  partially  decom- 
posed into  a  sulphuret  by  ignition,  with  flour,  sugar,  gum  arabic. 
starch,  &c. 

Baldwin's  phosphorus  is  fused  muriate  of  lime.  Homberg's  de- 
pends on  combustion.  (See  alum.) 

Herring,  mackarel,  (or  other  marine  fish,)  being  put  into  a  phial 
ivith  water  and  about  one  eighth  of  its  weight  of  common,  Epsom,  or 
Glauber's  salt,  and  conveyed  into  a  dark  place  ;  a  luminous  ring  is  seen 
after  three  days,  and  the  whole  fluid  appears  luminous  when  agitated.* 

The  phosphorescence  of  fish  when  hung  up  in  a  chimney  corner, 
and  of  rotten  wood,  &ic.  is  probably  owing  to  decomposition  prece- 
ding putrefaction.  Peat  earth  is  phosphorescent. 

Canton's  preparation  and  other  solar  phosphori,  on  being  exposed 
to  the  light,  shine  in  the  dark,  so  that  we  may  tell  the  hour  by  a 
watch,  and  when  they  cease  to  shine,  they  again  acquire  the  power 
by  a  new  exposure. 

(c.)  Some  bodies  become  phosphorescent  by  heat. — Fluor  spar, 
phosphate  of  lime,  many  varieties  of  feldspar,  and  many  lime  stones 
are  of  this  class.  It  is  usual  to  pulverize  them  coarsely,  and  to  throw 
them  upon  a  red  hot  shovel  in  a  dark  place.  The  fluor  spar  from 
Monroe,  seventeen  miles  west  from  New  Haven,  is  a  most  remarkable 


*  If  the  saline  solutions  are  too  strong  they  do  not  shine,  but  the  light  instantly 
appears  on  dilution  with  water.  Ebullition  destroys,  but  congelation  only  suspend* 
<he*  property,  which  appears  again  on  thawing. — Ure. 


30  LIGHT. 

example.*  It  gives  a  vivid  emerald  green  light  which  continues  for 
a  long  time. 

Some  varieties  of  marble,  heated  to  a  degree  that  would  only 
make  other  bodies  red,  emit  an  intensely  brilliant  white  light. — Tur. 

The  dried  yolk  of  an  egg  becomes  luminous  if  heated,  and  so 
does  tallow,  when  thrown  on  a  hot  shovel  or  burning  coals  ;  both  shov- 
el and  coals  should  be  rather  below  redness.  Some  bodies  ceasing 
to  emit  light  by  heat,  become  again  luminous  by  increase  of  heat. 

(d.)  Some  emit  light  by  percussion,  friction  or  pressure. — The 
Dolomite  of  Litchfield  county  in  Connecticut  faintly  flashes,  when 
pounded  in  a  mortar ;  light  is  seen  when  lumps  of  sugar,  or  of 
quartz,f  or  borax,  or  bonnet  cane,  are  smartly  rubbed  or  struck  to- 
gether, in  the  dark, — certain  varieties  of  tremolite  and  of  blende  give 
Jight  when  the  point  of  a  knife  is  drawn  across  them.J 

(e.)  Phosphorescence  is  seen  in  some  animals. 

The  glow  worm,  and  several  species  of  fire  fly  are  examples.  The 
luminousness  of  the  waves  of  the  sea  in  a  storm,  or  under  a  vessel's 
bow,  or  of  water  taken  from  the  sea  and  agitated,  is  very  remarka- 
ble ;  this  phosphorescence  is  owing  to  animal  matter  dissolved  in  die 
sea  water,  or  to  living  animals,  as  the  medusa,  cancer  fulgens,^  &c. 

When  the  sea  water  is  filtered  so  as  to  remove  the  animals,  it  is 
said  to  lose  its  phosphorescent  power. 

Lit.  H.  Ingalls,  of  the  U.  S.  Army,  is  of  opinion  that  the  phospho- 
rescence of  the  ocean  is  owing  to  the  ovula  of  fishes.  He  struck 
his  arm,  while  bathing,  against  a  soft  mass,  which  emitted  flashes  two 
qr  three  inches  long,  and  he  even  convinced  himself  that  there  was 
a  mild  degree  of  heat,  grateful  to  his  touch.  The  jelly  like  masses, 
seen  upon  a  beach  after  the  retiring  of  the  tide,  he  conceives  to  be 
the  bodies  in  question ;  that  these  masses  are  phosphorescent,  was 
proved  by  their  emitting  bright  light,  when  irritated  by  the  point  of 
a  pencil,  especially  in  a  particular  opake  point,  appearing  to  be  the 
punctum  saliens  of  a  living  animal  which  the  sun  hatches,  by  de- 
grees, from  the  jelly  like  mass,  and  the  tide  eventually  shakes  out. 
There  is  therefore  the  fullest  reason  to  believe  that  the  luminousness 
of  the  ocean  is  owing  to  animal  matter.  || 

Fresh  water  is  not  phosphorescent ;  the  waves  of  the  great  North 
American  lakes,  although  violently  agitated  by  tempests,  exhibit  no 
luminous  appearance.  Air  or  its  absence  has  no  effect  on  phospho- 
rescence. 

(/.)  Phosphorescence  is  produced  by  chemical  action. 

*  Am.  Jour.  II,  142. 

t  Quartz  phosphoresces  even  under  water. —  Ure. 

t  Dr.  Brewster's  Edin.  Phil.  Jour.  Vol.  I.  Nicholson's  Jour.  8vo.  Vols.  XV,  XVI 
and  XIX. 

§  Tilloch's  Phil.  Mag.  V.  37.  and  38.         ||  Trans,  of  Albany  Institute. 


LIGHT.  31 

Combustion  is  a  familiar  and  very  general  example.  Phos- 
phorescence, without  combustion,  is  seen  in  the  case  of  sulphuric  acid 
and  calcined  magnesia  ;  when  the  magnesia  has  been  recently  and 
thoroughly  calcined  and  the  sulphuric  acid  is  strong,  there  is  almost 
always  (especially  if  a  few  ounces  of  the  materials  be  used)  a  flash 
in  the  dark,  and  sometimes  it  is  visible  in  the  day  light. 

Lime  slaking  in  the  dark,  sometimes  shows  luminous  points. — 
Light  is  emitted  during  the  combination  of  sulphur  and  metallic 
filings,  as  copper  and  iron — of  potassium  and  sulphur,  iodine  and  phos- 
phorus, &c. ;  that  from  iodine  and  phosphorus  is  very  vivid.  It  is  ne- 
cessary only  to  throw  a  lijtle  iodine  upon  a  small  piece  of  phosphorus 
in  a  dry  wine  glass ;  the  action  is  speedy  or  even  instantaneous ;  a  mild 
heat  may  bring  it  on  when  it  is  tardy,  but  we  should  be  on  our  guard 
against  explosion.  The  same  remarks  will  apply  to  iodine  and  po- 
tassium, only  the  action  is  more  violent,  and  the  burning  potassium  is 
often  thrown  about  the  room. 

15.  LIGHT  is  A  CHEMICAL  AGENT. 

(a.)  It  acts  on  vegetables. — Etiolation  or  bleaching  of  vegetables 
by  tying  them  up,  takes  effect  in  consequence  of  the  exclusion  of 
light.  Celery  is  white,  mild,  and  agreeable  when  growing  beneath 
the  earth,  but  acrid,  and  as  is  said,  even  poisonous  if  growing  in  the 
light  ;  the  potatoe  root  is  affected  in  a  similar  manner  by  light. 
Shoots  of  potatoes,  turnips,  cabbage,  parsnip,  carrot,  fyc.  are  mild 
and  white  when  sprouting  in  a  moist,  dark  cellar,  but  if  a  beam  of 
light  crosses  them,  as  from  a  crack,  or  a  hole  in  a  window,  they  be- 
come colored  and  pungent,  and  incline  towards  the  light.  The  in- 
side leaves  of  heads  of  cabbage  or  lettuce  are  white  and  tender ;  so 
are  the  inner  coats  of  onions,  the  bottom  parts  of  blades  of  grass, 
especially  when  shooting  from  beneath  a  flat  stone,  and  vines  when 
growing  in  the  same  manner. 

The  bark  of  trees  is  generally  more  colored  than  the  wood — but 
ivoods  are  occasionally  deep  colored,  as  the  dye  woods  and  roots, 
logwood,  fustic,  brazil-wood,  lignum  vitae,  madder,  turmeric,  quercit- 
ron, alkanet,  &,c.  and  the  heart  of  wood  is  sometimes  more  deeply 
colored  than  the  superior  layers,  as  in  the  red  walnut. 

Many  causes  operate  besides  light,  e.  g.  heat,  air,  chemical  com- 
position, &tc.  But  even  colored  woods  generally  grow  deeper  color- 
ed by  exposure  to  light,  e.  g.  mahogany,  cherry,  black  walnut,  ma- 
ple, &c.  as  seen  in  common  furniture.  Red  roses  made  to  grow  in 
the  dark  become  white,  or  rather  the  trees  that  produce  red  roses  in 
the  light,  produce  white  ones  in  the  dark.* — Davy. 

?^.)  Although  the  color  of  vegetables  is  not  produced  exclusively 
^    ight,  it  is  owing  principally  to  that  cause. 

*  Many  shells  possess  rich  and  varied  colors,  which  from  their  original  situation 
never  have  enjoyed  direct  access  to  light. 


32  LIGHT. 

(c.)  Their  pungency  and  aromatic  properties  depend  very  much 
upon  the  light. 

-Plants  growing  in  the  dark  "contain  an  excess  of  saccharine  and 
aqueous  particles  5"  they  are  destitute  of  color,  odor,  and  pungency, 
but  acquire  these  properties  if  transferred  to  the  light.* 

(d.)  Light  is  most  abundant  in  the  torrid  zone,  and  there  the  ver- 
dure is  the  most  intense ;  there  also  we  find  the  richest  gums  and 
resins  and  the  most  odorant  aromatics,  and  the  foliage  is  there  most 
abundant ;  but  other  causes  besides  light  contribute  to  these  effects,  as 
heat  and  moisture. 

(e.)  Light  extricates  oxygen  gas  from  fresh  green  vegetables, 
which  may  be  collected  in  an  inverted  bell  glass,  full  of  water,  and 
containing  the  plant  also.  Carbonic  acid  gas  is  evolved  in  the  night. 

(/.)  Light  is  a  stimulus  to  vegetables. — Their  leaves  incline  to- 
wards the  light :  plants  growing  in  windows  do  this :  some  flowers 
open  their  petals  to  the  light  and  shut  them  at  night. 

Camphor  kept  in  glass  bottles  exposed  to  light,  crystallizes  in  the 
most  beautiful  symmetrical  manner,  and  more  particularly  on  the  side 
next  to  the  light. 

(g.)  Light  sometimes  weakens  or  discharges  color. — Yellow  wax 
in  thin  layers  becomes  white ;  stamped  goods,  as  curtains,  and  those 
stuffs  that  are  colored  in  the  thread,  as  carpets,  have  their  colors 
faded  by  light :  these  colors  are  usually  of  vegetable  origin,  modified 
more  or  less  by  mineral  mordants. 

16.  LIGHT  ACTS  ON  ANIMALS. 

(a.)  Light  exalts  the  color  of  animals. — Worms, grubs,  and  larger 
animals  that  live  in  the  ground,  are  generally  possessed  of  dull  colors, 
without  beauty  or  vivacity. 

Birds  and  insects  of  night  are  generally  of  dull  hues. — Owls, 
night-hawks,  whip-poor-wills,  certain  varieties  of  snipes  or  wood- 
cocks, &c.  and  the  insects  of  summer  evenings,  have  generally  no 
beauty  of  color. 

(b.)  The  opposite  is  true  of  a  great  proportion  of  the  various 
classes  of  animals  that  are  much  abroad  in  the  day  light. 

Generally  the  vivacity  of  color  is  greatest  in  the  animals,  birds  and 
insects  of  the  tropical  regions,  and  the  opposite  is  true  of  die  polar : 
the  temperate,  as  we  might  suppose,  occupy  a  middle  rank  in  these 
respects. 

*  Dr.  Robinson,  "  in  the  drain  of  a  coal  work  under  ground,  accidentally  laid  his 
hand  upon  a  very  luxuriant  plant,  with  large  indented  foliage  and  perfectly  white. 
He  had  not  seen  any  thing  like  it,  nor  could  any  one  inform  him  what  it  was.— 
He  had  the  plant  with  a  sod,  brought  into  the  open  air  in  the  light.  In  a  little 
time  the  leaves  withered  and  soon  after  new  leaves  began  to  spring  up  of  a  green 
color  and  of  a  different  shape  from  that  of  the  old  ones.  On  rubbing  one  of  the 
leaves  between  his  fingers,  he  found  that  it  had  the  smell  of  common  tansy,  and 
ultimately  proved  to  be  that  plant,  which  had  been  so  changed  by  growing  in  the 
dark." — Rees'  Cyclopedia. 


LIGHT.  33 

These  can  be  regarded  as  only  general  truths  subject  of  course  to 
many  exceptions  and  qualifications. 

In  birds,  the  parts  exposed  to  the  light,  as  the  back  and  breast,  are 
always  colored,  but  the  feathers  beneath  the  wings  and  under  the 
belly  are  usually  white. — So  the  back  and  fins  of  fishes  are  colored, 
while  the  belly  is  white.  Snakes  and  other  reptiles,  and  the  am- 
phibious animals  are  distinguished  in  the  same  manner. 

(c.)  The  color  of  the  human  species  is  generally  graduated  in  tol- 
erable accordance  with  the  quantity  of  light ;  black  people  are  not  found 
perhaps  any  where  except  within  the  tropics,  and  white  ones  no  where 
but  in  the  northern  temperate  zone ;  but  the  state  of  society,  food, 
habitations,  employments,  and  many  other  causes,  modify  these  results, 
and  it  is  to  be  observed,  that  the  colored  people  of  polar  climates,  are 
all  barbarians,  living  in  smoke,  filth,  exposure  and  wretchedness.* 

(d.)  The  color  of  persons,  of  the  various  classes  and  conditions 
of  society,  accords  with  this  view. — Students  and  artisans,  working 
within  doors,  and  women,  whose  employments  are,  in  this  coun- 
try, generally  in  the  house,  are  of  lighter  complexions ;  while  far- 
mers, sailors,  soldiers,  &c.  are  more  deeply  colored.  Many  other 
causes,  especially  those  affecting  the  state  of  health,  do  however  mod- 
ify these  results. 

(e.)  Light  is  necessary  to  health  and  cheerfulness. — Animals  and 
men,  confined  in  darkness,  become  gloomy,  and  their  health  and  their 
faculties  are  gradually  impaired. 

In  the  human  subject,  when  long  deprived  of  light,  dropsy  is  said 
often  to  terminate  life. 

Other  physical  causes  also  operate,  as  want  of  exercise  and  bad 
air,  and  moral  causes  must  also  powerfully  affect  the  human  mind. 

Even   animals   are  affected,   in  a  way  somewhat  analogous. 

18.  LIGHT  ACTS  ON  MINERAL  BODIES. 

JVitric  acid  is  decomposed  into  nitrous  acid  and  oxygen  gas. 

•Aqueous  solution  of  chlorine  gives  out  oxygen  and  muriatic  acid, 
and  most  rapidly  in  the  most  refrangible  rays. 

Metallic  oxides  are,  in  some  instances,  decomposed ;  the  oxides  of 
mercury  sometimes  give  running  mercury. 

fVhite  muriate  of  silver  becomes  dark,  and  even  black,  muriatic 
acid  gas  being  formed. 

Chlorine  and  hydrogen  gases,  in  equal  volumes,  explode  by  the 
stroke  of  the  solar  ray  and  very  quickly  in  the  violet  ray. 

Phosphorus  which  is  white,  when  first  distilled  in  hydrogen  gas, 
becomes  colored,  yellow  and  brown,  by  the  action  of  light. 

Substances  wet  with  nitrate  of  silver,  become  dark,  and  even  black, 
by  exposure  to  the  sun. 

*  See  Dr.  S.  S.  Smith's  Essay ;  also  the  learned  work  of  Dr.  Pritchard,  on  the 
physical  history  of  man. 

5 


34  LIGHT, 

19.  LIGHT  PRODUCES  MAGNETISM. 

This  was  first  observed  more  than  twenty  years  since  by  Morrichini, 
at  Rome,  and  has  been  recently  confirmed  by  Mrs.  Somerville.  (Ph. 
Tr.)  A  sewing  needle,  an  inch  long,  being  half  covered  with  paper, 
had  the  other  half  exposed,  during  two  hours,  to  the  violet  rays,  which 
imparted  north  polarity ;  the  indigo  rays  produced  nearly  the  same 
effect,  and  the  blue  and  green  in  a  still  smaller  degree.  The  yellow, 
orange,  red,  and  invisible  rays  were  inert,  having  produced  no  effect 
in  three  days.  Similar  effects  were  produced  when  the  needles 
were  enclosed  in  green  or  blue  glass,  or  ribands  of  the  same  color ; 
one  half  being  always  covered  with  paper.  The  calorific  rays  pro- 
duced no  effect.  In  these  experiments  it  was  not  necessary  to  dark- 
en the  room. 

Iron*  ore  not  magnetic,  becomes  so  by  exposure  to  light,  f 

REMARK. 

When  we  have  considered  radiant  heat,  certain  discrimination* 
may  be  made  between  it  and  light,  properly  so  called. 

Some  of  the  effects,  above  described,  probably  belong  to  one  sort  of 
solar  rays,  and  some  to  another,  but  the  facts  are  stated  with  refer- 
ence to  the  undecomposed  rays,  as  they  come  to  us  from  the  sun. 

20.  SOURCES  OF  LIGHT,  most  of  ivhich  are  also  sources  of  heat. 

1.  The  Sun  and  fixed  stars. 

2.  Combustion. 

3.  Heat  without  combustion,  as  in  an  ignited  stone. 

4.  Percussion  and  friction. 

5.  Chemical  action  without  combustion. 

6.  Electric  and  Voltaic  action. 

7.  Animal  poiver,  as  in  phosphorescent  living  animals. 

"  Organization,  sensation,  spontaneous  motion  and  all  the  opera- 
tions of  life,  exist  only  at  the  surface  of  the  earth,  and  in  places  ex- 
posed to  the  influence  of  light.  Without  it  nature  would  be  lifeless 
and  inanimate.  By  means  of  light,  the  benevolence  of  the  Deity 
hath  filled  the  surface  of  the  earth  with  organization,  sensation  and 
intelligence." — Lavoisier. 

PHOTOMETER. 

Mr.  Leslie,  by  having  one  ball  of  his  differential  thermometer  J 
made  of  black  glass,  adapts  it,  as  he  conceives,  to  the  measurement 
of  light ;  but  it  seems  difficult  to  distinguish  in  this  case,  between  the 
effects  of  heat  and  of  light,  unless  we  adopt  the  opinion  of  the  in- 
genious inventor,  that  light,  when  absorbed,  is  converted  into  heat. 

*  Fer  oxidule  of  Hatty.          t  Am.  Jour.  I.  89 

t  For  the  notice  of  this  instrument,  see  thermometers. 


HEAT  OR  CALORIC.  35 

SEC.  II.    HEAT  OR  CAIA)RiC. 

GENERAL    NATURE    OF    THIS    POWER. 

1.  The  sensation  produced  in  us,  by  a  hot  body,  ive  attribute  to  a 
power  which  we  call  heat — meaning  that  which  is  the  cause   of  the 
sensation. 

2.  This  cause  is  unknown — but,  as  that  which  excites  in   us  the 
sensation  of  heat,  produces  at  the  same  time,  expansion  in  all   the 
bodies,  with  which  it  communicates,  both  effects   are  attributed  to 
one  cause. 

3.  The  cause  of  heat  and  of  expansion  are  therefore  assumed  to  be 
one  and  the  same,  and  this  unknown  cause  is  called,  in  modern  chemi- 
cal language,  Caloric;    (Calor,  Lat.  Calorique,  Fr.)*    but  to  avoid 
pedantry  and  repetition,  the  terms,  HEAT  and  CALORIC,   are  both 
occasionally  used  to  denote  the  cause  in  question. 

4.  Our  sensations  of  heat  and  cold  are  dependent,  principally,  on 
the  motion  of  Caloric. 

(a.)  When  it  is  entering  our  bodies,  we  feel  warm  or  hot ;  when 
it  is  leaving  us,  we  feel  cool  or  cold,  as  the  process  is  in  either  case 
more  or  less  rapid. 

(b.)  More  accurately  speaking — we  feel  hot,  or  cold,  according 
as  the  quantity  of  heat,  that  enters  or  leaves  us,  is  greater  or  less  than 
the  average  quantity  to  which  we  are  accustomed — for  heat  is  always 
flowing  from  us  during  life,  and  generally  more  rapidly  than  it  is  re- 
ceived, from  without,  as  our  natural  temperature  is  higher  than  the  aver- 
age temperature  of  the  air.  If  therefore,  we  lose  more  heat  than  we 
are,  on  the  whole  accustomed  to  lose,  we  feel  cold,  and  the  reverse. 

(c.)    Cold  is  merely  a  negation  of  heat. 

The  same  person  may  feel  heat  and  cold  in  different  parts  of  his 
frame  at  the  same  time;  for  instance,  by  dipping  at  the  same  mo- 
ment, one  hand  in  cold,  the  other  in  hot  water ;  or,  by  laying,  simul- 


*  The  new  nomenclature  of  Chemistry  had  its  origin  in  France. 

The  necessity  of  this  reform  arose  from  the  progress  of  discovery.  The  language 
of  Chemistry  had  become  both  erroneous  and  imperfect.  Some  newly  discovered 
bodies  had  no  names;  many  old  names  were  false,  and  others  barharous  or  ridicu- 
lous. The  period  was  about  1785,  at  which  time  the  new  nomenclature  wa*  per- 
fected. The  p'incipal  agents  in  this  reform  were  Lavoisier,  Fourcroy,  Morveau, 
and  Berthollet.  Movveau  proposed  the  measure  in  1782.  The  nomenclature  will 
be  explained  in  detail,  as  the  terms  occur. — See  Jour,  de  Phy.  Tome  10.  p,  370. 

My  much  respected  teacher,  Professor  HOPE,  of  the  University  of  Edinburgh, 
at  first  colleague,  and  afterwards  successor  to  Dr.  Black,  was  perfectly  familiar 
with  the  illustrious  LAVOISIER,  in  the  later  periods  of  his  life,  andwas  fully  ac- 
quainted with  his  discoveries  and  researches.  Dr.  Hope  returned  from  Paris  to 
Scotland,  strongly  imbued  with  the  new  views,  and  was  the  first  public  teacher  in 
Britain  who  made  them  known,  and  who  adopted  the  new  nomenclature  in  his  lec- 
tures. I  had  this  from  him  when  I  was  his  pupil. 

The  late  Dr.  Pearson,  of  London,  was  also  one  of  the  first  who  promulgated  the 
modern  nomenclature  and  discoveries  in  Great  Britain. 


36  HEAT  OR  CALORIC. 

laneously,  one  hand  on  ice,  and  the  other  on  a  living  warm  blooded 
animal. 

Three  persons,  in  the  same  atmosphere,  may  find  it  cold,  hot  or 
temperate,  according  to  their  previous  exposure — their  state  of 
health,  or  their  clothing.  To  bring  this  to  a  trial,  let  one  person 
come  suddenly  out  of  a  bath  of  98°  or  100°  ;  let  another  come  from 
an  ice  house,  and  another  from  the  temperature  of  55°,  into  a  room 
of  the  same  degree  of  heat.  The  first  will  feel  cold — the  second 
warm,  and  the  third  will  experience  no  change. 


(d.)    Without  motion  there  is  no  sensation. 
Tl 


motion  of  light  -      produces       vision, 

That  of  air,  -        "  hearing, 

That  of  odorant  matter     -  -    "  smell, 

*That  of  sapid  substances,    -  "  taste, 

*And  that  of  all  bodies  in  contact  with  us,       "  feeling. 

Lavoisier. 

(e.)  But  mere  sensation  would  not  decide  that  there  are  not  two 
causes,  one  of  cold,  arid  one  of  heat ;  or  that  cold  is  not  the  positive 
principle,  and  heat  the  negation. 

Only  reverse  the  reasoning — if  we  would  contend  that  cold  is  the 
sole  principle  ;  or  reason  in  both  modes,  if  we  would  admit  that  both 
causes  operate.  For  instance — Caloric  enters  us,  or  cold  leaves  us, 
and  we  feel  warm ;  or  cold  enters  us,  or  heat  leaves  us,  and  we  feel 
cold.f  But,  to  assign  two  or  more  causes,  when  one  is  sufficient  is 
contrary  to  sound  philosophy. 

(/".)   The  sun  is  a  permanent  source  of  heat. 
There  is  no  permanent  source  of  cold,  and  no  fact  can  be  stated 
on  that  subject  which  is  not  explained  upon  the  supposition  of  the 
privation  of  heat.  J 

5.  The  common  opinion,  that  some  bodies  are  positively  and  in- 
herently hot,  and  some  cold,  is  erroneous. 

(a.)  We  could  have  no  certain  information  on  this  subject,  except 
from  the  changes  in  volume,  or  in  their  qualities,  which  various 
bodies  undergo,  when  those  that  are  supposed  to  contain  more  or 
less  of  heat  are  applied  to  them. 

For  instance,  the  thermometer  is  our  criterion,  and  its  fluid  either 
shrinks  or  swells,  according  as  the  body  in  contact  with,  or  near  it, 
is  colder  or  hotter  than  it. 

Fluids  become  solid,  and  again  fluid,  or,  in  other  words,  freeze 
and  melt,  according  to  the  variations  in  the  quantity  of  heat. 


*  In  the  two  latter  cases,  contact  produces  the  sensation,  but  without  motion  it  is 
soon  diminished,  and  in  the  last  instance,  soon  ceases. 

t  We  must  in  this  case,  substitute  and  for  or,  if  we  would  suppose  both  cause* 
.operating  at  the  same  time. 

t  The  apparent  radiation  of  cold  will  be  mentioned  hereafter. 


HEAT  OR  CALORIC.  37 

(I.)  There  is  heat  in  every  thing,  even  in  ice  itself ;  and  there  is 
no  reason  to  believe  that  we  have  ever  attained  the  maximum  of 
cold. 

6.  THERE  ARE  RAYS  OF  HEAT,  DISTINCT  -FROM  LIGHT. 

(a.)  They  obviously  pass  from  all  hot  or  warm  bodies,  whether  lu- 
minous or  not. 

(b.)   They  flow  from  nearly  all  luminous  bodies. 

(c.)  From  living  animals. 

(d.)  From  hot  water,  and  other  hot  fluids,  excluding  those  that 
require  ignition  to  sustain  their  fluidity. 

(e.)  From  a  hot  ball  of  iron  which  is  not  luminous ;  from  a  hot 
stone,  a  hot  brick,  or  other  heated  incombustible  body.* 

(f.)  From  a  close  stove — supposing  no  chinks  for  the  light  to 
pass,  and, 

(g.)  Probably  from  all  bodies  whatever,  and  at  all  temperatures, 
there  is  a  certain  amount  of  radiation  of  heat,  although  die  colder 
the  body  is,  the  less  the  radiation  will  be. 

7.  RAYS  OF  CALORIC  ARE  EMITTED  FROM  THE  SUN,  and  they 
are  capable  of  being  separated  from  those  of  light. 

(a.)  Dr.  Herschel,  using  the  telescope  to  look  at  the  sun,  em- 
ployed colored  glasses  to  diminish  the  light; — when  their  color  was 
deep  enough  to  screen  the  eyes,  the  glasses  became  hot  and  crack- 
ed ;  in  some  cases  there  was  very  little  light,  while  the  heat  was  painful 
to  the  eye,  and  some  glasses  transmitted  much  light  but  very  little  heat. 
He  therefore  examined  the  heating  power  of  the  different  rays,  sep- 
arating them  by  a  prism,  and  permitting  the  different  colored  rays  in 
the  well  known  order  of  red,  orange,  yellow,  green,  blue,  indigo, 
violet,  to  fall  on  a  delicate  thermometer — two  other  thermometers 
being  placed  near,  as  standards ;  the  thermometer  which  indicated 
the  heat,  lay  upon  an  inclined  table. 

(b.)  The  heat  was  greatest  in  the  red,  or  least  refrangible  rays  ; 
and  it  was  least  in  the  violet,  or  most  refrangible.  If  when  in  the 
violet  it  was  as  16 — in  the  green,  it  was  as  22.4,  and  in  the  red,  55. 

(c.)  The  greatest  illuminating  power  ivas  in  the  middle  of  the 
spectrum,  and  it  diminished  either  way. 

(d).  When  the  thermometer  was  carried  beyond  the  red  ray,  and  in 
the  same  line,  the  fluid  still  continued  to  rise  ;  the  maximum  effect  was 
half  an  inch  beyond  the  red,  fyc.  ;  one  inch  beyond,  the  same  as  in 
the  middle  of  the  red  ray ;  the  heating  power  was  sensible  at  one 
and  a  half  inch  beyond  the  red  ray. 

(e.)  The  focus  of  heat  is  probably  not  less  than  one  fourth  of  an 
inch  farther  from  the  lens  than  the  focus  of  light. f 

*  They  are  supposed  to  be  hot,  in  order  that  the  radiation  may  be  evident :  the 
radiation  would  exist,  although  in  a  less  degree,  if  the  bodies  were  cold. 
t  Phil.  Trans.  1800,  pp.  258—9. 


38 


HEAT  OR  CALORIC. 


The  following  figures  represent  the  prism  and  prismatic  spectrum. 

Should  a  ray  fall  upon 
a  prism,  as  represented 
in  the  figure,  in  the  di- 
rection of  the  line,  AB; 
it  will,  on  account  of  the 
obliquity  of  its  approach, 
be  refracted  towards  C, 
and  emerging  thence, 
obliquely  to  another  sur- 
face of  the  prism,  H  C  K, 
it  will  again  be  most  at- 
tracted by  that  portion  of  the  surface  towards  which  it  inclines. 
Consequently,  it  will  be  refracted  so  as  to  proceed  in  the  direction 
of  CD. 

Thus  it  must  be  evident,  that  two  surfaces  of  the  prism  have  a 
concurrent  influence,  in  bending  the  rays  from  their  previous  course, 
while  in  the  pane,  the  influence  of  one  surface  is  neutralized  by  that 
of  the  other. 

The  lines,  L  F,  and  E  F,  being  perpendiculars  to  the  surfaces 
of  the  prism,  A  B  L,  is  the  angle  of  incidence,  and,  G  B  C,  the 
angle  of  refraction,  to  the  surface  at  which  the  rays  enter  the  prism. 
F  C  B,  is  the  angle  of  incidence,  and  E  C  D,  the  angle  of  refrac- 
tion to  the  surface,  from  which  the  rays  emerge. — Dr.  Hare. 

A    TRIANGULAR    GLASS    PRISM,    CONVENIENTLY    MOUNTED    ON  A   UNI- 
VERSAL   JOINT. 

This  figure  represents  a  triangu- 
lar  glass  prism,  mounted  upon  a 
universal  joint,  supported  by  a 
brass  stand,  so  as  to  be  well  qualifi- 
ed for  "the  dispersion  of  light. 

A,  The  glass  prism,  supported 
at  each  end  by  a  pivot. 

B  B,  Handles  by  means  of 
which  the  pivots  are  turned,  so  as 
to  make  the  prism  revolve. 

C  C,  Ball  and  socket,  forming 
a  joint,  upon  which  the  plate  D  D, 
may  be  moved,  so  as  to  assume 
any  serviceable  position. — Dr.  Hare. 

Let  A  B,  represent  a  part  of  a  window  shutter  of  a  room,  into 
which  light  enters  only  through  the  hole  C.  If  the  light  thus  enter- 
ing be  received  on  a  screen,  a  circular  spot  on  it  will  be  made  lumi- 


HEAT  OR  CALORIC.  39 

nous.  But  if  a  glass  prism,  D  O  E,  be  placed  before  the  hole  so 
that  the  light  may  fall  upon  the  prism,  perpendicularly  to  its  axis, 
the  rays  which  had  before  produced  the  luminous  circle  will  be  re- 
fracted and  dispersed,  so  as  to  form  the  spectrum,  r  g  #,  consisting 
of  the  following  colors  arranged  in  the  following  order — red,  orange, 
yellow  green,  blue,  indigo,  violet. 


Dr.  Hare. 

(/.)  These  experiments  have  been  fully  confirmed  by  those  of  Sir 
H.  C.  Englefield. — Mur.  In  his  experiments  there  could  be  no 
source  of  deception,  because  each  kind  of  rays,  first  separated  by 
the  prism,  was  made  to  pass  successively  through  a  four  inch  lens 
covered  by  pasteboard,  except  at  one  place,  where  was  a  slit  in  the 
paper — the  focus  was  thus  formed  in  the  air  and  the  thermometers 
were  there  applied. 

In  Dr.  Herschel's  experiment,  as  the  rays  were  thrown  on  a  table, 
some  fallacy  might,  possibly,  have  been  suspected,  from  the  reflection 
of  the  rays.  In  Englefield's  experiment,  the  thermometer  gave  the 
following  results. 

Ray.  Time.  Quantity.       Ratio  of  the  effect. 

Blue  in  3'    from    55°  56°  1. 

Green  „  3        «      54    58  4. 

Yellow  „  3        «      56    62  6. 

Full  red  „  21      <•       56    72  7.2 

Confines  of  red    „  2|      "      58    731  6.6 

In  full  dark,  but  near  the  red  in     21      "       61     79  21.6 

The  difference  in  the  heating  power  of  the  spectrum  is  so  great,  as 
to  be  perceptible  to  the  naked  hand. 

(g.)  Berard  confirmed  HerschePs  and  Englefield's  experiments 
substantially.* 

*Ann.  Phil.  II,  163. 


40  HEAT  OR  CALORIC. 

With  him  the  heating  power  increased  from  the  violet  to  the  red 
jay.  The  greatest  heating  power  was  in  the  red  extremity  of  the 
spectrum  and  not  beyond  it.  His  maximum  of  heat  was  where  the 
thermometer  was  still  covered  by  the  red  ray.  The  fluid  in  the  ther- 
mometer sunk  as  it  receded  from  the  red  ray,  and  entirely  out  of  the 
red  ray,  where  Herschel  fixed  the  maximum,  its  elevation  above  the 
air  around,  was  only  one  fifth  of  what  it  had  been  in  the  red  ray. 

(A.)  Red  rays  are  considered  as  cheerful,  because  warmth  and 
therefore  comfort,  is  found  to  be  associated  with  them  ;  such  rays  are 
emitted  by  burning  charcoal  and  coke,  and  by  a  common  wood  fire ; 
those  from  burning  alcohol,  especially  if  mixed  with  salt,  are  pale, 
and  have  very  little  heat  in  them,  and  are  therefore  regarded  as 
gloomy. 

Mr.  Seebeck  has  proved  that  the  place  of  the  greatest  heat  de- 
pends very  much  upon  the  nature  of  the  prism  :  thus,  when  it  is  of 
crown  or  plate  glass,  the  maximum  effect  is  in  the  middle  of  the  red 
— if  of  flint,  it  is  beyond  the  red  ;  if  a  hollow  glass  prism  be  filled 
with  water,  the  greatest  effect  is  in  the  yellow ;  and  if  with  sulphuric 
acid,  it  is  in  the  orange ;  so  that  different  substances  appear  to  differ 
in  their  power  of  refracting  caloric.*  Still  the  important  fact  is  con- 
firmed, that  there  are  rays  of  caloric,  that  they  are  differently  refran- 
gible from  rays  of  light,  and  that  they  possess  unequal  refractive 
power. 

8.  RAYS  OF  CALORIC  ALONG  WITH  RAYS  OF  LIGHT  ARE  EMITTED 

FROM   ALL    BURNING    BODIES,    AS    WELL    AS    FROM    THE    SUN. 

(a.)  A  plate  of  glass,  presented  to  a  common  fire,  intercepts  the 
heat,  but  permits  most  of  the  light  to  pass,  while  it  becomes  itself  hot. 

(6.)  A  bright  metallic  plate  reflects  both  the  light  and  the  heat,  and 
does  not  become  hot. 

(c.)  The  same  plate,  if  blackened  with  smoke,  ink  or  paint,  be- 
comes hot,  and  then  ceases  to  reflect  either  light  or  heat. 

(d.)  A  glass  mirror  reflects  only  the  light  of  a  common  fire,  for 
it  absorbs  the  heat  and  becomes  sensibly  'hot ;  the  focus  is  therefore 
luminous  but  not  hot. 

In  the  sun's  rays  it  forms  both  a  luminous  and  a  hot  focus,  and 
therefore  reflects  both  the  heat  and  light. 

(e.)  A  metallic  mirror  acts  in  the  same  manner,  and  also  with  a 
common  fire,  it  reflects  both  the  light  and  the  heat ;  if  blackened,  it 
reflects  neither,  but  becomes  itself  hot. 

(/.)  A  lens,  before  an  artificial  fire,  becomes  hot,  and  forms  only  a 
luminous  image ;  presented  to  the  sun,  it  concentrates  both  the  light 
and  heat,  and  produces  both  a  bright  and  a  hot  focus,  while  it  scarcely 
becomes  heated  at  all. 


Edin.  Jour,  of  Science,  No.  1,  pa.  358. 


HEAT  OR  CALORIC.  44 

(g.)  The  panes  of  a  common  window  do  not  become  heated  by 
the  passage  of  the  sun's  rays  through  them ;  or  at  most,  the.  effect  is 
scarcely  perceptible. 

(h.)  Rays  of  caloric  pass  through  glass  with  difficulty,  if  the  tem- 
perature be  below  that  of  boiling  water,  but  they  traverse  it  with  a 
facility  always  increasing  with  the  temperature  of  the  body  emitting 
the  heat,  as  it  approaches  the  point  where  bodies  become  luminous. — 
Hen. 

(i.)  Calorific  rays  that  have  already  passed  through  a  glass  screen 
pass  through  another  with  much  greater  facility.  Rays  emitted  by  a 
hot  body  differ  in  their  power  of  passing  through  glass. 

"  A  thick  glass,  though  as  permeable  to  light  as  a  thin  glass  of  a 
worse  quality,  or  even  more  so,  allows  a  much  less  quantity  of  radiant 
heat  to  pass ;  but  the  difference  is  so  much  the  less  as  the  tempera- 
ture of  the  radiating  source  is  more  elevated,"*  * 

9.  RAYS  OF  CALORIC,  EMITTED  FROM  HOT  BUT  NOT  LUMINOUS 
BODIES,  CAN  BE  REFLECTED  BY  MIRRORS,  AND  BROUGHT  TO  A 

FOCUS. 

Hot  water,  hot  mercury,  and  hot,  but  not  luminous  solid  bod- 
ies are  good  examples  ;  e.  g.  a  cannon  ball,  a  stone,  &c. 

(a.)  In  making  these  experiments,  either  one  mirror  or  two  may 
be  employed.  The  mirrors  should  be  of  copper,  plated  with  silver; 
or,  brass  or  tin  will  answer  very  well,  if  highly  polished. 

(b.)  If  one  mirror  be  employed,  the  hot  body  should  be  placed  in 
the  axis  of  the  mirror  and  the  thermometer  in  the  focus ;  if  two  mir- 
rors are  employed,  the  thermometer  should  occupy  one  focus  and 
the  hot  body  the  other. 

10.  RAYS    ARE    EMITTED    BY  THE    SUN    WHICH  DO  NOT  PRODUCE 
EITHER  HEAT  OR  VISION,    BUT  EFFECT  CERTAIN    CHEMICAL  DECOM- 
POSITIONS OR  COMBINATIONS. 

(a.)  Muriate  of  silver  is  tarnished  or  blackened  by  the  sun's  rays — 
but  in  the  prismatic  spectrum,  this  effect  is  least  in  the  red  ray,  and 
increases  constantly  towards  the  violet ;  the  ratio  of  the  blue  and 
red  rays  is  inversely,  as  1 5  to  20 — that  is,  to  produce  a  given  effect 
in  fifteen  minutes  by  the  blue,  requires  twenty  in  the  red. 

(b.)  Beyond  the  violet  ray,  the  same  effect  is  still  produced  in  the 
dark. 

(c.)  Berard,f  by  a  lens,  concentrated  that  part  of  the  spectrum, 
from  the  green  to  the  violet,  and  by  another  the  portion  from  the 
green  to  the  red.  The  focus  of  the  last  was  a  white  point,  scarcely 
tolerable  to  the  eye,  but  it  did  not  alter  the  muriate  of  silver  in  two 
hours:  the  other  focus  was  much  less  bright  and  less  hot,  but 
blackened  the  muriate  in  less  than  six  minutes. 

*  De  la  Roche,  Annals  of  Phil.  II,  100.  t  Ann.  of  Phil.  II,  165. 

6 


4:2  HEAT  OR  CALORIC. 

(d.)  Guiacum  passed  from  yellow  to  green  during  the  exposure  at 
the  violet  end,  and  returned  to  yellow  at  the  red  end  :  this  is  supposed 
to  be  an  anomaly,  as  Dr.  Wollaston  ascertained  that  the  change  to 
green  is  connected  with  the  absorption  of  oxygen,  and  this  principle  is 
usually  separated  at  the  violet  end. 

(e.)  It  is  said  that  phosphorus,  which  kindles  easily  at  the  red  ex- 
tremity of  the  spectrum,  is  extinguished  at  the  violet  end. 

(/.)  The  combination  of  chlorine  and  hydrogen  is  effected  rapidly 
by  the  red  rays,  but  without  explosion ;  but  the  aqueous  solution  of 
chlorine  becomes  muriatic  acid  most  rapidly  in  the  violet  rays  :  "  the 
violet  rays  produce  upon  moistened  red  oxide  of  mercury  the  same 
effects  as  hydrogen  gas." — Davy. 

(g.)  ''Persons  who  had  persisted  in  a  long  course  of  pills,  formed 
by  nitrate  of  silver  (lunar  caustic)  and  bread,  acquired  a  blue  tinge 
in  the  skin,  and  in  one  case  this  was  deepened  by  exposure  to  light.* 

CONCLUSIONS. 

11.  THE     SUNBEAMS     CONTAIN      THREE     DIFFERENT     KINDS     OF 
RADIANT  MATTER. 

(a.)  At  least  it  is  convenient,  provisionally  so  to  regard  them,  as 
the  effects  are  thus  best  understood. 

(6.)  It  is  possible,  however,  that  they  may  all  be  varieties  of  one 
thing,  and  the  apparent  difference  may  be  owing  to  unknown  causes. 

(c.)  The  rays  of  the  sun  then    appear  to  contain 

A.  Rays  that  illuminate,  but  do  not  cause  warmth  or  expansion; 
they  may  be  called  colorific  rays. 

B.  Rays  that  cause  warmth  and  expansion,  but  do  not  illuminate ; 
they  are  opake,  and  may  be  called  calorific  rays. 

C.  Rays  that  produce  neither  color,  nor  heat,  nor  expansion,  but 
that  cause  certain  chemical  effects;  they  also  are  opake  and  may  be 
called  chemical  rays :  by  some  they  have  been  called  de-oxidizing  or 
hydrogenating  rays.     The  first  term  is  preferable,  on  account  of 
its  brevity. 

12.  These  three  kinds  of  rays  all  come  from  the  sun  in  company; 
hence  the  triple  effect  of  the  solar  beam,  in  warming  and  causing 
expansion,  in  illuminating  or  imparting  color,   and  in  producing  cer- 
tain chemical  effects. 

13.  In  the  moon's  rays,  there  is  chiefly  light  with  little  or  no  heat. 
Mr.  Brande  has  ascertained,  that  the  lunar  rays  do  not  blacken 

muriate  of  silver. f 

Popular  opinion  ascribes  to  them  the  power  of  stimulating  vegeta- 
tion, and  of  causing  putrefaction  in  fish  and  other  animal  bodies,  upon 
which  they  may  chance  to  fall. 

14.  Culinary  fire,  as  all  knoiv,  emits  both  the  luminous  and  the  heat- 

*  Cooper's  Thomson,  note,  edit.  1818,  Vol.  I.  p.  34.  t  lire's  Diet.  p.  567. 


HEAT  OR  CALORIC.  43 

ing  rays; — but  it  has  not  been  ascertained  that  the  de-oxidizing  chem- 
ical rays  are  present.* 

15.  The  physical  laws  of  all  the  three  varieties  of  rays  are  nearly 
the  same,  differing  a  little  in  the  amount  of  the  effect. 

(a.)  They  are  refrangible  ;  this  is  proved  by  their  passing  through 
the  prism,  and  being  all  made  to  deviate  from  their  course. 

(6.)  They  are  refrangible  in  different  degrees  ;  and  this  is  true, 
whether  we  compare  one  sort  of  rays  with  another,  or  the  rays  of 
one  kind  individually  among  themselves. 

(c.)  Some  rays  of  each  kind  are  equally  refrangible,  and  are  there- 
fore found  in  company  through  the  whole  spectrum. 

(d.)  Some  rays  of  caloric  are  less  refrangible  than  any  of  the 
other  rays  of  either  kind ;  therefore  they  are  found  outside  of  the 
red  rays  in  the  dark. 

(e.)  Some  of  the  chemical  rays  are  more  refrangible  than  any 
other,  of  either  kind  ;  hence  they  are  found  outside  of  the  violet  ray, 
and  in  the  dark. 

(/.)  The  spectrum,  then,  is  composed  of  the  three  sorts  of  rays,  but 
it  is  terminated  by  calorific  rays  on  one  side,  and  by  chemical  rays 
on  the  other ;  on  both  wings  it  has  opake  rays,  but  of  different  kinds. 

(g.)  Jill  the  kinds  of  rays  are  reflexible. — This  is  evident  from  the 
effect  of  mirrors ;  and  Scheele  long  ago,  ascertained  the  equality  of 
the  angles  of  incidence  and  reflection. 

(h.)  At  a  given  distance  from  the  radiant  point,  the  intensity  of 
both  heat  and  lightf  is  inversely  as  the  square  of  the  distance,  e.  g. 
At  the  distances  2,  3,  4,  it  is  as  4,  9,  and  16  inversely. 

16.  It  is  probable  that  all  the  three  kinds  of  rays  are  emitted  from 
the  sun,  and  other  sources  with  equal  velocity. 

We  are  not  informed  as  to  what  is  the  cause  of  the  differences  be- 
tween solar  and  culinary  heat. 

17.  It  is  evident,  that  the  particles  of  all  the  three  varieties  of  rays 
are  minute,  to  a  degree  beyond  our  powers  of  conception  ;  probably 
they  are  equally  minute,  but  of  this  we  are  not  certain. 

18.  It  is  evident,  therefore  that  we  cannot  expect  to  ascertain  the 
weight  of  either  of  these  kinds  of  rays ;  as  already  remarked,  our 
organs,  and  our  instruments  are  too  coarse  for  such  delicate  trials. 

19.  There  is  a  great  analogy  between  light  and  heat — they  agree 
in  nearly  all  their  physical  properties;  but  light  produces  vision  and 
colors — caloric,  expansion  and  heat. 

(a.)  Light  cannot  be,  at  all,  imprisoned. — When  the  source  from 
which  it  flows  is  intercepted,  except  in  the  case  of  the  solar  phos- 

*  Neither  muriate  of  silver,  nor  a  mixture  of  chlorine  and  hydrogen  gases,  was 
affected  by  the  concentrated  light  from  the  burning  carburetted  hydrogen  gases ; 
but  the  light  from  electrized  charcoal  speedily  blackened  the  muriate,  and  exploded 
the  chlorine  and  hydrogen,  or  caused  them  to  combine  quietly.— Grande. 

t  The  chemical  effect  probably  follows  the  same  law ;  possibly  also  the  magnetic. 


44  HEAT  OR  CALORIC. 

phori,  it  vanishes  instantly,  and  leaves  no  trace  behind — all  i- 
darkness. 

(b.)  Light  can  be  entirely  excluded. — Although  it  seems  to  pene- 
trate and  enter  all  bodies,  it  shines  through  none  but  those  that  are 
called  transparent  or  translucent. 

(c.)  Heat  can  be  partially  imprisoned. — When  the  sources  from 
which  it  flows  are  intercepted,  its  effects  do  not  instantly  vanish,  but 
decline  gradually. 

(d.)  Heat  cannot  be  entirely  excluded. — It  makes  its  way,  more  or 
less  rapidly,  through  all  kinds  of  matter. 

EFFECTS     OF    HEAT,     OR     CALORIC,     AND     PRINCIPAL    DIVISIONS    OF 

THE    SUBJECT. 

Certain  effects  on  the  form,  and  other  properties  and  powers  of  bod- 
ies, are  observed  to  arise  from  the  addition  and  abstraction  of  heat. 
They  may  be  embraced  under 
I.   Expansion, 
II.  Distribution  of  temperature, 

III.  Congelation  and  liquefaction, 

IV.  Vaporization  and  gazification, 
V.  Natural  evaporation, 

VI.  Ignition, 

VII.    Capacity  for  heat — Specific  Heat, 
VIII.    Combustion. 

APPENDIX. 

The  sources  of  heat  and  cold. 

I.  EXPANSION. 

1.  By  expansion,  is  intended  an  increase  of  the  three  corporeal 
dimensions,  length,  breadth  and  thickness. — Contraction  is  of  course 
the  opposite  of  this. 

(a.)  The  entrance  of  heat  into  a  body  produces  the  same  result, 
in  regard  to  its  dimensions,  as  if  more  matter  were  added  to  it. 

(6.)  The  abstraction  of  heat  gives,  in  this  respect,  the  same  re- 
sult, as  if  matter  were  taken  from  the  body  all  around. 

Swelling  and  shrinking,  then,  are  produced  by  heating  and  cooling. 

(c.)  The  absolute  weight  of  a  body  is  not  altered,  if  the  weight  be 
estimated  in  vacuo ;  but  if  it  be  weighed  in  any  surrounding  medi- 
um, whose  density  does  not  vary  during  the  experiment,  the  specific 
gravity  of  the  body  will  be  found  to  change  with  the  temperature. 

(c?.)  The  experiments  are  supposed  to  be  conducted  at  such  a 
temperature  as  not  to  produce  decomposition. 

2.  Bodies  in  all  the  three  states,  solid,  fluid  and  aeriform,  are 
subject  to  the  law  of  expansion. 

(a.)  *fl.s  an  instance  of  the  expansion  of  solids,  an  iron  cylinder 
neatly  turned,  and  fitted  to  a  gauge  by  which  its  dimensions  are  meas- 
ured, answers  very  well. — Its  length  is  received  between  two  pro- 


HEAT  OR  CALORIC. 


45 


jections,  and  its  diameter  in  a  hole.  If  it  fit  these  dimensions  at  the 
common  temperature — it  will  be  too  large  if  made  red  hot,  and  too 
small  if  cooled  by  ice. 

Cylinder.  Length.  Diameter. 


An  Iron  ball  just  fitting  an  iron  ring  so  as  to  pass  through  it  when 
cold,  will  not  pass  when  red  hot,  but  when  cold  will  pass  as  before. 
— L.  u.  K. 

(6.)  A  pear  shaped  glass,  thin  at  bottom,  with  a  perforated  cork, 
containing  a  long  narrow  tube,  inserted  into  the  neck — the  glass  be- 
ing filled  with  a  colored  fluid,  exhibits  strikingly  the  expansion  and 
contraction  of  fluids ;  it  is  necessary  only  to  heat  and  cool  the  ball. 

Alcohol  is  more  expansible  than  water,  but  on  account  of  its  com- 
bustibility, care  should  be  taken  that  none  of  it  is  spilled  into  the 
fire  ;  a  scale  may  be  attached  to  the  tube,  and  then  the  expansions 
and  contractions  will  be  very  visible.  The  thermometer  demon- 
strates the  same  facts. 

EXPANSION  OF  LIQUIDS. — Dr.  Hare. 

Liquids  are  expanded  when  their  temperature  is  raised;  and  some 
liquids  are  more  expansible  than  others. 


N 


N 


46  HEAT  OR  CALORIC. 

Let  two  globular  glass  vessels,  with  long  narrow  necks,  as  nearly 
as  possible  of  the  same  size  and  shape,  be  supplied  severally,  with 
water  and  alcohol,  excepting  the  necks  from  N  N  to  O  O.  Under 
each  vessel,  place  equal  quantities  of  charcoal,  burning  with  a  similar 
degree  of  intensity.  The  liquids  in  both  vessels  will  be  expanded, 
so  as  to  rise  into  the  necks ;  but  the  alcohol  will  rise  higher  than  the 
water. — Hare. 

(c.)  A  retort  of  glass  inverted  with  its  mouth  in  a  colored  fluid 
gives  out  air,  if  the  ball  be  heated ;  and  if  the  heat  be 
withdrawn,  the  column  of  fluid  ascends  and  occupies  the 
place  of  the  air  that  was  expelled.  A  heated  ladle  an- 
swers well  to  hold  over  the  bulb  of  the  retort. 

The  experiment  will  be  more  striking  if  the  retort  has 
a  very  long  and  narrow  neck,  or  if  a  tube  be  inserted  in 
the  mouth  to  elongate  the  neck. 

A  moist  flaccid  bladder  with  the  neck  tied,  is  swollen  by 
the  application  of  heat,  and  bursts  if  the  heat  be  great ; 
it  is  of  course  contracted  when  the  heat  is  withdrawn. 
In  this  experiment,  hot  water  is  a  good  medium  for  the  expansion, 
and  cold  water  for  the  contraction. 

(flf.)  The  pyrometers  described  in  the  books  of  natural  philosophy 
demonstrate  the  expansion  of  solids  with  great  delicacy.* 

An  excellent  pyrometer  has  been  executed  by  Mr.  Terry,  of  Salem, 
Connecticut.  A  small  iron  cylinder  is  heated  by  a  long  thin  wick 
fed  by  alcohol,  contained  in  a  horizontal  slitted  tube,  and  by  means  of 
levers  and  multiplying  wheels,  the  motion  is  so  increased,  that  an  in- 
dex moves  rapidly  over  a  graduated  circle,  and  the  opposite  motion 
takes  place  when  the  cylinder  is  cooled.  Any  other  metal  may  be 
substituted.  One  of  these  instruments  is  in  the  laboratory  of  Yale 
-College.  We  subjoin  a  figure  of  a  similar  pyrometer  used  by  Dr. 
Hare. 


*  See  Webster's  Manual,  p.  23 ;  Ann.  de  Chim.  et  de  Phys.  V.  312,  Breguet ; 
and  Journal  of  Science,  XI.  809,  Daniel,  and  especially  the  Library  of  Useful 
Knowledge,  Art.  Pyrometer. 


HEAT  OR  CALORIC. 


47 


Influence  of  temperature  on  the 
length  of  a  metallic  wire  acting 
on  an  index  through  intervening 
levers. 

W  W  represents  a  wire,  beneath 
which  is  a  spirit  lamp,  consisting  of 
a  long,  narrow,  hollow  triangular 
vessel  of  sheet  copper,  open  along 
the  upper  angle,  so  as  to  receive 
and  support  a  strip  of  thick  cotton 
cloth,  or  a  succession  of  wicks. 
By  the  action  of  the  screw  at  S, 
the  wire  is  tightened  ;  and  by  its 
influence  on  the  levers,  the  index 
I  is  raised.  The  spirit  lamp  is 
then  lighted,  and  the  wire  is  en- 
veloped with  flame.  It  is  of  course 
heated  and  expanded ;  and,  allow- 
ing more  liberty  to  the  levers,  the 
index,  upheld  by  them,  falls. 

By  the  action  of  the  screw  the 
wire  may  be  again  tightened,  and 
the  application  of  the  lamp  being 
continued,  will  again,  by  a  further 
expansion,  cause  the  depression  of 
the  index ;  so  that  the  experiment 
may  be  repeated  several  times  in 
succession. 

Since  this  figure  was  drawn,  I 
have  substituted  for  the  alcohol 
lamp,  the  more  manageable  flame 
of  hydrogen  gas,  emitted  from  a 
row  of  apertures  in  a  pipe  supplied 
by  a  self-regulating  reservoir  of 
hydrogen  gas,  of  which  an  engra- 
ving and  description  will  be  given 
in  due  time. 

If  while  the  index  is  depressed, 
by  the  expansion,  ice  or  cold 
water  be  applied  to  the  wire,  a 
contraction  immediately  follows, 
so  as  to  raise  the  index  to  its  ori- 
ginal position. — Dr.  Hare. 


48  HEAT  OR  CALORIC. 

3.  In  general,  different  solid  or  fluid  bodies  expand  variously,  by 
the  same  amount  of  heat,  and  no  satisfactory  theorem  has  been  dis- 
covered on  this  subject :  the  facts  are  ascertained  by  experiment. 
The  following  metals  are  arranged  in  the  order  of  their  expansibility, 
the  most  expansible  being  placed  first ;  zinc,  lead,  tin,  copper,  bis- 
muth, iron,  steel,  antimony,  palladium,  platinum. — Henry. 

It  is  said  by  Dr.  Ure,  that  equal  increments  of  heat  produce  equal 
degrees  of  expansion  in  metallic  bodies  :*  and  that  the  reverse  is 
true  for  the  decrements. 

Table  of  expansion,  by  Ellicott.-\ 

Gold.  Silver.  Brass.  Copper.  Iron.  Steel.  Lead. 

73°          103°          95°  89°  60°  56°         147° 

By  a  table  of  Smeaton,  (Mur.)  zinc  appears  to  exceed  lead  in  ex- 
pansibility. There  appears  to  be  no  relation  between  the  density  and 
expansibility  of  solid  bodies,  gold  being  less  expansible  than  brass  or 
lead  :  but  there  is  a  tolerably  regular  relation  between  the  expansi- 
bility and  the  fusibility;  e.g.  antimony,  bismuth,  tin,  lead  and  zinc 
being  most  expansible  and  most  fusible ;  in  Smeaton's  table,  anti- 
mony is  stated  as  expanding  less  than  iron,  and  bismuth  than  copper, 
but  these  deviations  may  arise  from  errors  in  the  experiments.! 

4.  Gases  are  the  most  expanded,  and  with  them  all  aeriform  bod- 
ies: fluids  are  much  less  expanded  than  gases,  and  solids  vastly  less 
than  fluids. 

Beneath  is  Mr.  Dalton's  table  of  some  common  liquids :  the  volume 
at  32°  is  denoted  by  1 ;  the  expansion  is  for  180°,  from  32°  to  212°. 
Mercury,  .0200 =j\ 

Water,  -     .0446=¥V5 

saturated  with  salt,     -  .0500 =¥V 

Sulphuric  acid,        -  -     .0600=T'T 

Muriatic  acid,     -  .0600=Ty 

Oil  of  turpentine,     -  -     .0700 =TV 

Ether,        -  .0700  =  T'T 

Fixed  oils,     -  -     .0800=  rV5 

Alcohol,     -  .0110=i" 

Nitric  acid,     -  -     .0110  =  1 

Generally  the  expansion  of  fluids  increases  as  we  ascend  the  scale. 
Mr.  Dalton,§  thinks  that  the  expansion  of  fluids  is  as  the  square  of 
the  temperature  from  the  point  of  congelation  or  of  greatest  density. 
This  is  not  sufficiently  confirmed  by  experiment.  || 

5.  Caloric  introduced  among  the  particles  of  bodies  is  a  power  of 
repulsion  tending  to  produce  expansion. 


*  Phil.  Trans.  1818.        t  Phil.  Trans,  xlyii.  485. 

:f  Murray,  Vol.  I.  p.  163,  2d  edition.         §  New  system  of  Chemical  Philosophy. 

!|  Murray,  I.  173,  2d  edition. 


HEAT  OR  CALORIC1.  49 


fa.)  The  antagonist  power  is  cohesion. 


Therefore,  as  regards  all  the  three  forms  of  matter,  solid, 
fluid,  and  gaseous,  the  expansion  varies  with  the  ratio  of  these  two 
forces ;  only  one  of  which  exists  in  the  gases. 

6.  GASES  AND  ALL  AERIFORM  BODIES  EXPAND  ALIKE.* 

(a.)  One  body,  of  this  class,  corresponds  with  one  of  another  class; 
e.  g.  carbonic  acid  gas  with  hydrogen,  steam  with  vapor  of  alcohol,  &c. 

(b.)  The  same  body  corresponds  with  itself,  equal  variations  of 
temperature  producing  equal  variations  of  volume,  in  different  parts 
of  the  scale. 

(c.)  The  reason  of  this  exception  is  obvious,  as  in  aeriform  bodies 
there  is  no  cohesion  to  overcome;  the  power  of  the  heat  is,  therefore, 
the  same  upon  them  all. 

7.  Fluids  expand  very  unequally. 

(a.)  In  general,  the  lower  the  boiling  point  of  a  fluid  is,  the  more 
it  is  expanded  by  heat,  and  vice  versa,  as  is  seen  in  ether,  alcohol, 
water,  and  mercury. 

(b.)  In  general,  also,  the  expansibilities  of  liquids  are  inversely  as 
their  boiling  temperatures. — Thomson. 

(c.)  In  any  given  liquid,  the  expansibility  increases  with  the  rise 
of  temperature,  and  those  are  the  most  equal,  whose  boiling  point  is 
the  highest. 

(d.)  The  expansibility  of  fluids  does  not  follow  the  ratio  of  the 
density. 

(e.)  It  increases  very  rapidly  as  we  approach  the  boiling  point. 


*  Mr.  Dalton  of  Manchester,  (Eng.)  and  Gay  Lussac  of  Paris,  ascertained,  by 
numerous  experiments,  that  the  expansion  of  all  bodies,  in  the  form  of  air,  is  the 
same,  for  equal  additions  of  heat;  and  moreover,  that  the  expansion  of  any  one  agri- 
form  body  is  nearly,  although  not  perfectly,  equable  for  equal  additions  of  heat,  in 
different  parts  of  the  scale. 

It  was  formerly  believed,  that  every  different  gas  was  affected  differently  by  heat, 
and  tables  of  expansion  of  the  different  gases  were  constructed,  but  this  variation 
was  owing  to  the  presence  of  water  in  all  experiments  before  those  of  Dalton  and 
Gay  Lussac,  as  the  vapor  mixing  with  the  gas  under  examination,  must  neces- 
sarily falsify  the  result. 

100  cubic  inches  of  common  air,  in  passing  from  212°  to  1035°  become  250.    cub.  in. 
100         do.  common  air,    "  "      32°  "   212°       «       137.5 

100         do.  water,  "  "       do.  "    do.         "       104.5        " 

100         do.  iron,  '*  "       do.  "    do.         "       100.1         «« 

The  expansion  of  air  is  then  eight  times  greater  than  that  of  water,  and  that  of 
water  forty  five  times  greater  than  that  of  iron.  The  expansion  of  any  one  gas  ap- 
parently diminishes  a^little  as  the  temperature  increases;  it  is  however  probable 
that  this  difference,  as  it  is  so  very  small,  is  only  apparent. 

Dalton  informs  us  that  the  expansion  of  100  cubic  inches  of  air,  from  55°  to  133£°, 
or  for  the  first  77<|0,  was  167;  and  from  133£°  to  212°,  or  the  second  77^°,  it  was 
only  158 :  but  if  this  difference  be  imputed  to  inaccuracy,  we  may  conclude  that  the 
expansion  is  equable.  Aeriform  bodies  expand  one  four  hundred  and  eighty  third 
part  of  their  volume  for  every  degree  of  Fahrenheit  between  freezing  and  boiling.— 
Vide  Manches.  Memoirs,  V.  593 ;  Th.  1. 338 ;  and  Ann.  de  Chim.  xliii.  137,  and  v.  43. 

7 


50  HEAT  OR  CALORIC. 

8.  Solids  expand  very  unequally,  and  as  far  as  has  been  discover- 
ed,* follow  no  general  law. 

9.  There  are  partial  exceptions  to  the  law  of  expansion  in  certain 
parts  of  the  scale  of  heat,  but  none  on  the  whole,  for  through  a  wide 
range  of  temperature,   all   bodies  expand  by  heat  and  contract  by 
cold. 

(a.)  Solid  iron,  bismuth,  and  antimony,  float  on  the  surface  of 
their  respective  fluids,  formed  by  melting. 

Such  metals  and  their  compounds  are  peculiarly  fitted  for  taking 
impressions  from  moulds,  as  by  their  expansion  in  cooling,  they  fill 
every  part,  and  copy  the  most  delicate  ramifications. 

(6.)  The  expansion  in  freezing  is  generally  attributed  to  a  kind 
of  crystallization — but  mercury,  and  nitric  and  sulphuric  acids  con- 
tract, although  they  suffer  a  partial  crystallization. 

(c.)  Salts  generally  expand  in  crystallizing,  and  frequently  break 
the  bottles  containing  them. 

(d.)  Water  is  the  most  remarkable  exception,  but  it  exists  only 
within  a  limited  number  of  degrees. 

In  cooling,  it  attains  its  maximum  of  density  at  40°,  when  it  be 
gins  to  expand,  and  continues  to  do  so  as  it  cools  below  40° ;  its  ex- 
pansion is  the  same  for  any  equal  number  of  degrees  above  and 
below  40°  ;  e.  g.  at  32°  and  48°. 

If  water  be  cooled  below  32°  without  freezing,  it  goes  on  expand- 
ing, and  the  same  relations  of  density  are  maintained. 

Pure  ice  floats  on  water,  about  one  eighth  or  one  ninth  of  its 
volume  being  out,  as  is  seen  to  a  certain  degree,  in  the  icebergs.f 

(e.)  The  fact  respecting  water's  being  an  exception  from  the 
law  of  expansion,  is  well  exhibited,  by  taking  two  thermometer  balls 
with  tubes  attached,  and  filling  one  ball  with  water  and  the  other  with 
alcohol ;  both  may  be  immersed  in  melting  snow,  or  in  freezing 
water,  and  the  difference  will  be  very  manifest,  if  the  experiment  be 
commenced  above  40°.  The  alcohol  will  sink  regularly,  but  the 
water  at  40°  will  begin  to  rise  in  the  tube,  and  will  continue  to  rise 
till  it  freezes. 

(/.)  Water,  in  the  act  of  freezing,  expands  more  than  it  does 
when  heated  from  the  freezing  to  the  boiling  point.  { 


*  It  has  however  been  ascertained  by  Petit  and  Dulong  that  at  high  temperatures, 
solids  dilate  in  an  increasing  ratio.— Jinn,  de  Ch.  and  Phy.  Vol.  7,  and  Turner's 
Chem.  p.  20.  For  a  table  of  the  expansion  of  various  substances,  see  the  latter 
author  same  page. 

t  Anchor-ice.  Is  it  formed  on  the  bottom  of  running  streams,  on  account  of  the 
conducting  power  of  stones  ? 

t  This  is  beautifully  illustrated,  by  immersing  in  a  freezing  mixture,  a  ball  filled 
with  water,  and  having  a  tube  attached  to  it ;  as  the  fluid  approaches  freezing,  and 
especially  when  it  begins  to  freeze,  it  will  rise  out  of  the  top  of  the  tube. 


HEAT  OR  CALORIC.  51 

The  sp.  gr.  of  water  at  60°  being  assumed  at  1,  that  of  ice  at  32°, 
is  only  .92.* 

(g.)  Were  it  not  for  the  exception  above  described,  water  would 
begin  to  freeze  at  the  bottom  of  rivers  and  lakes. 

10.  Cause  of  the  expansion  of  water  in  freezing,  and  for  eight 
degrees  above,  f 

(a.)  There  can  be  little  doubt  that  it  is  owing  to  crystallization,  de- 
pending on  corpuscular  attraction,  which  begins  to  operate  even  before 
congelation.  Water  in  freezing,  assumes  a  linear  arrangement :  lines 
of  ice  intersect  each  other  at  60°  and  120°;  this  is  seen  distinctly  in  a 
shallow  freezing  pond,  or  in  a  basin  of  water :  also  in  snow  flakes,  which 
are  usually  stars  of  six  rays,  or  confused  bundles  of  prismatic  crys- 
tals ;  distinct  crystals,  prisms  of  six  sides,  are  often  seen  on  a  cellar 
wall  in  winter,  or  in  a  moist  bank,  and  hoar  frost  is  a  collection  of 
crystals  of  ice. 

(6.)  The  particles  of  water  are  supposed  to  be  endowed  with  a 
kind  of  polarity,  which  causes  the  volume  to  expand,  in  consequence 
of  the  attraction  of  certain  points,  edges  or  angles. 

(c.)  An  illustration  is  derived  from  magnetic  needles  thrust 
through  corks,  and  thrown  upon  water ;  they  would  arrange  them- 
selves as  the  aqueous  particles  are  supposed  to  do  in  crystallizing. — 
Dr.  Black. 

11  When  the  freezing  of  water  is  examined  by  the  microscope,  this 
peculiarity  of  arrangement  can  be  observed,  the  lines  shooting  out 
from  each  other  at  an  angle  either  of  60°  or  of  120°. "{ 

1 1 .  Effects  of  unequal  expansion  of  water,  and  of  its  expansion 
infreezing. 

(a.)  The  bursting  of  domestic  vessels  in  which  water  freezes ;  the 
flaking  of  the  glazing  from  earthen  vessels. 

(b.)  The  bursting  of  water  pipes,  of  wood  or  metal,  when  not 
adequately  protected. 


*  Webster,  p.  25. 

t  This  expansion  was  denied  by  Mr.  Dalton,  who  attributed  it  to  the  contraction  of 
the  glass  exceeding  that  of  the  water,  and  vice  versa — its  expansion  exceeding  that 
of  the  water,  in  the  specified  degrees  between  32°  and  40°. 

This  question  was  however  fully  settled  by  Dr.  Hope,  and  Mr.  Murray,  and  this 
inequality  is  considered  as  well  established.  See  the  controversy  ably  stated  in 
Murray,  Vol.  I.  p.  194,  &c. 

Sir  Charles  Blagden  ascertained  that  when  water  is  prevented  from  freezing  at 
32°,  by  being  kept  perfectly  still,  the  water  still  continues  to  expand,  even  for  ten 
or  more  degrees  below  the  ordinary  freezing  point,  and  this  in  even  a  greater  ratio ; 
and  if  the  freezing  point  be  reduced,  by  mixing  salt  with  the  water,  the  contraction 
begins  at  about  the  same  distance  from  the  point  at  which  the  particular  solution 
does  freeze. 

•  Mr.  Dalton  succeeded  (Manchester  Memoirs,  v.  374,)  in  cooling  water  down  so 
far  without  freezing,  that  from  expansion,  it  had  risen  as  high  as  the  point  to 
which  it  would  have  been  raised  had  it  been  heated  to  75°.  "  Its  real  temperature 
must  then  have  been  10°.  On  freezing,  it  darted  suddenly  up  to  128°." 

t  Murray,  2d  Ed.  Vol.  I.  p.  182. 


52  HEAT  OR  CALORIC. 

(c.)  The  raising  of  pavements,  and  of  the  surface  of  the  ground, 
like  a  honey  comb,  thus  breaking  and  preparing  it,  so  that  the  veget- 
able fibres  can  penetrate  it. 

(d.)  The  throwing  down,  or  distortion  of  stone  walls,  in  moist  land. 

(e.)  The  cracking  of  timber,  and  even  of  rocks,  sometimes  with 
explosion,  in  very  cold  countries. 

(f.)  The  bursting  of  closed  cannon  and  bomb  shells,  when  water 
is  congealed  in  them. 

Huygens  burst  an  old  cannon,  and  Major  Williams  burst  bomb- 
shells at  Quebec.  In  one  of  his  experiments,  "  an  iron  plug,  2  f 
pounds  weight,  was  projected  from  a  bomb-shell,  to  the  distance  of 
four  hundred  and  seventy  five  feet,  with  a  velocity  of  more  than 
twenty  feet  in  a  second." 

(g.)  Water,  being  confined  by  means  of  a  moveable  plug  or  stop- 
per, in  a  strong  brass  tube,  three  inches  in  diameter,  raised  seventy- 
four  pounds,  when  it  froze. — Boyle. 

(h.)  The  Florentine  academicians  burst  a  hollow  brass  ball,  one 
inch  in  diameter,  by  freezing  the  water  with  which  it  was  filled. 
Muschenbroeck.  calculating  from  the  tenacity  of  brass,  and  the  thick- 
ness of  the  ball,  inferred,  that  the  expansive  force  was  equal  to  twen- 
ty seven  thousand  seven  hundred  and  twenty  pounds. 

12.  But  for  the  inequality  of  water  in  contracting,  just  before  its 
congelation,  the  globe  would  not  be  long  habitable. 

(a.)  There  are  both  ascending  and  descending  currents  in  water, 
while  cooling  or  heating. 

(5.)  In  the  case  of  cooling  water,  these  currents,  while  unobstruct- 
ed, tend  to  cool  it  equally. 

(c.)  In  consequence  of  the  exception  that  has  been  stated,  they 
are  arrested  at  40°,  and  then  the  surface  water  does  not  descend  any 
more. 

(d.)  It  remains,  is  cooled,  and  freezes,  and  the  ice,  being  a  bad 
conductor  of  heat,  greatly  retards  the  freezing  of  the  water  below. 

(e.)  Thus  only  a  few  inches,  or  at  most  feet  of  ice  are  formed, 
and  the  next  summer  is  sufficient  to  thaw  it. 

(/.)  Were  it  not  for  this  peculiarity,  the  deep  rivers  and  lakes  in 
cold  latitudes  would  freeze  to  the  bottom,  and  therefore  would  never 
thaw  again,  as  the  summer  would  not  be  long  enough  for  that  pur- 
pose. 

(g.)  The  process  would,  every  winter,  advance  farther  and  farther 
towards  the  equator,  and  ultimately  the  ocean  would  freeze  as  solid 
as  stone. 

(h.)   Thus,  animal  and  vegetable  life  would  be  finally  extinguished. 

(i.)  All  this  mischief  is  prevented  by  this,  apparently,  trifling  and 
really  solitary  exception,  evidently  instituted  on  purpose  by  the  Cre- 
ator, one  of  whose  characteristics  it  is,  to  effect  the  greatest  results 
by  the  smallest  means. 


HEAT  OR  CALORIC.  53 

(j.)  "  The  sheet  of  ice  which  often  covers  the  small  seas,  as  well 
as  the  rivers  and  lakes,  not  only  preserves  a  vast  body  of  heat  in  the 
subjacent  water,  but  when  it  thaws,  the  fish  are  not  destroyed  by  the 
cold ;  for  not  a  particle  of  the  cold  surface  water  can  descend  until 
a  change  in  the  atmosphere  has  taken  place,  so  as  to  raise  the  tem- 
perature of  the  whole  of  the  water,  at  least  ten  degrees.* 

13.  Popular  uses  of  expansion  and  contraction. 

(a.)  Iron  hoops  and  tires  are  heated  red  hot,  and  suddenly  cooled 
to  bind  the  parts  of  carriage  wheels,  of  burr  millstones,  &tc. 

(6.)  Clocks  and  watches  gain  in  cold  weather,  owing  to  the  con- 
traction of  the  metal,  and  vice  versa. 

A  pendulum  vibrating  seconds,  by  a  change  of  temperature  of  30° 
will  alter  its  length  about  j^Vo  part,  which  will  change  its  rate  of 
going  eight  seconds  a  day.  Or  if  the  ball  of  a  pendulum  vibrating 
seconds  be  lowered  T{^  of  an  inch,  the  clock  will  loose  ten  seconds 
in  twenty  four  hours. — Hen. 

(c.)  The  Compensation  pendulum  is  easily  explained,  by  a  model 
or  diagram  ;  one  kind,  called  the  gridiron  pendulum,  consists  of  bars 
of  different  expansibility,  and  having  different  points  of  support,  the 
opposite  expansions  balancing  each  other.  Harrison  employed 
three  bars  of  steel,  and  two  of  a  compound  of  zinc  and  silver,  and 
they  were  so  arranged  that  the  expansion  of  the  steel  counteracted  that 
of  the  other  metals,  so  that  the  pendulum  did  not  alter  in  length. 
Graham  substituted  for  the  bob  of  the  pendulum,  a  glass  cylinder 
about  six  inches  deep,  and  holding  ten  or  twelve  pounds  of  mercury, 
the  expansion  of  which  upward,  compensated  for  that  of  the  steel 
pendulum  rod  downward. — L.  u.  K. 

(d.)  The  cracking  of  thick  glass,  by  sudden  heating  or  cooling, 
is  owing  to  unequal  expansion  ;  thin  glass  does  not  crack,  because  the 
heat  makes  its  way  through  the  glass  so  rapidly,  that  the  internal  and 
external  expansion  are  nearly  alike  ;  otherwise  there  would  be  a 
strain,  and  glass  always  cracks  on  the  colder  surface,  whether  hot 
glass  is  suddenly  exposed  to  cold,  or  the  reverse. 

(e.)  Expansion  and  contraction,  by  temperature,  is  capable  of  over- 
coming great  force. 

The  two  side  walls  of  a  gallery  at  the  Conservatoire  des  Arts  et 
Metiers,  being  pressed  outward  by  the  incumbent  weight,  M.  Molard 
perforated  the  walls  on  opposite  sides,  and  introduced  strong  iron 
bars,  whose  ends  were  left  to  project  beyond  the  walls,  and  were 
furnished  with  strong  circular  iron  plates,  fitted  on  so  as  to  screw. 

The  bars,  being  then  heated,  increased  in  length,  and  the  plates 
now  separated  from  the  wall,  were  screwed  up  so  as  to  touch  it. 
The  bars,  on  cooling,  contracted,  and  drew  the  walls  closer  together. 

*  Parkes'  Chemical  Essays,  VoM.  p.  61. 


54 


HEAT  OR  CALORIC. 


The  process  being  repeated,  the  walls  were  brought  into  the  perpen- 
dicular position,  and  if  necessary,  could  have  been  curved  inward. 


— L.  u.  K. 

THERMOMETERS,    CONSTRUCTION,    USE,  &IC. 

1.  The  common  thermometer,  and  most  pyrometers,  operate  upon 
the  principle  of  expansion. 

(a.)  The  thermometer  ivas  probably  invented  by  Sanctorio,  an 
Italian  physician  of  the  seventeenth  century.  His  thermometer  was 
merely  a  ball  blown  on  the  end  of  a  glass  tube,  and  inverted  in  a 
fluid ;  it  was  consequently  subject  to  the  pressure  of  the  atmosphere, 
a  change  in  which  might  cause  a  movement  of  the  fluid,  although 
the  temperature  should  be  stationary.  This  thermometer  is  entirely 
unfit  for  being  used  in  fluids — still  it  is  very  useful,  as  an  air  ther- 
mometer, for  measuring  minute  variations  of  temperature. 

Air  Thermometer  of  Sanctorio,  on  a  large  scale. 

The  bulb  of  a  mattrass  is  sup- 
ported, by  a  ring  and  an  upright 
wire,  with  its  neck  downwards, 
so  as  to  have  its  orifice  beneath 
the  surface  of  the  water  in  a  small 
glass  jar.  A  heated  iron  being1 
held  over  the  mattrass,  the  con- 
tained air  is  so  much  increased  in 
bulk,  that  the  vessel  being  inade- 
quate to  hold  it,  a  partial  escape 
from  the  orifice  through  the  water 
ensues.  On  the  removal  of  the 
hot  iron,  as  the  residual  air  regains 
its  previous  temperature,  the  por- 
tion expelled  by  the  expansion  is 
replaced -by  the  water. 

If  in  this  case  the  quantity  of 
air  expelled  be  so  regulated,  that 
when  the  remaining  portion  re- 
turns to  its  previous  temperature, 
the  liquid  rises  about  half  way  up 
the  stem,  or  neck,  the  apparatus 
will  constitute  an  air-thermometer.  For  whenever  the  temperature 
of  the  external  air  changes,  the  air  in  the  bulb  of  the  mattrass  must, 
by  acquiring  the  same  temperature,  sustain  a  corresponding  increase 
or  diminution  of  bulk,  and  consequently,  in  a  proportionable  degree, 
influence  the  height  of  the  liquid  in  the  neck.  This  thermometer  is 
very  sensible  and  would  be  very  accurate,  but  that  it  is  influenced 


HEAT  OR  CALORIC. 


55 


by  the  variations  of  atmospheric  pressure  as  well  as  by  thermomet- 
rical  changes. — Dr.  Hare. 

(b.)  Leslie's  differential  thermometer. — For  the  construction  of  this 
instrument,  a  ball  is  blown  at  each  end  of  a  glass  tube  bent  twice  at 
right  angles. 

The  tube  contains  usually  sulphuric  acid  colored  by  carmine — the 
balls  contain  air,  which,  as  well  as  the  contained  fluid  has  no  com- 
munication with  the  atmosphere. 

(c.)  It  indicates  only  the  difference  of  temperature  between  the  two 
balls. — It  is  very  useful  in  delicate  experiments  on  heat,  where  the 
variations  of  temperature  are  minute. 

(d.)  Howards  improvement  of  Leslie's  thermometer. 

Dr.  Howard  of  Baltimore,*  has  substituted  ether  for  the  sulphuric 
acid — the  ether  is  boiling  when  the  instrument  is  sealed,  and  therefore 
there  is  a  vacuum  over  the  fluid,  except  that  the  space  is  filled  with 
the  vapor  of  ether  ;  this  instrument  is  vastly  more  sensible  than  Les* 
lie's  original  one,  and  with  it  the  heat  was  believed  to  be  discovered  in 
the  moon's  rays  by  Dr.  Howard. f 


DIFFERENTIAL  THERMOMETER. 


o      o 


This  instrument  consists  of  a  glass  tube 
nearly  in  the  form  of  the  letter  U,  with  a  bulb 
at  each  termination.  In  the  bore  of  the 
tube  there  is  some  colored  liquid,  as  for  in- 
stance, sulphuric  acid,  alcohol,  or  ether. — 
When  such  an  instrument  is  exposed  to  any 
general  alteration  of  temperature  in  the  sur- 
rounding medium,  as  in  the  case  of  a  change 
of  weather,  both  bulbs  being  equally  affected, 
there  is  no  movement  produced  in  the  fluid ; 
but  the  opposite  is  true,  when  the  slightest 
imaginable  calorific  influence  exclusively  af- 
fects one  of  the  bulbs.  Any  small  bodies, 
situated  at  different  places  in  the  same  apart- 
ment warmed  by  a  fire,  will  show  a  diversity 
of  temperature,  when  severally  applied  to  the 
different  bulbs. — Dr.  Hare. 


2.  CONSTRUCTION  OF  THE  COMMON  THERMOMETER. 

Sa.)   Take  a  glass  tube,  of  uniform  bore,  sealed  at  the  glass-house. 
ts  uniformity  is  ascertained  by  introducing  a  little  mercury,  and 


*Lond.  Quar.  Sci.  Jour.  Vol.  8.  pa.  219. 


t  Am.  Jour.  Vol.  II,  pa.  329, 


56  HEAT  OR  CALORIC. 

letting  it  pass  along  the  tube,  from  end  to  end,  measuring  it,  at  short 
intervals,  with  a  scale  or  dividers.* 

(b.)  Although  the  tube  should  not  be  quite  uniform,  it  may  be  stilt 
used.\ 

(c.)  To  blow  the  ball,  the  instruments  wanted  are  the  bloiv  pipe, 
and  an  elastic  gum  bottle  which  is  useful,  perhaps  necessary,  where 
the  thermometer  must  be  exact — that  is  free  from  air  and  moisture. 
We  need  also  pliers  and  some  bladed  instrument.  The  glass  is 
melted,  drawn  in  two,  and  thus  hermetrically  sealed  at  one  end, 
while  it  is  opened  at  the  other  by  cracking  it,  after  marking  it  with  a 
file ;  the  end  on  which  the  ball  is  to  be,  is  then  rounded,  by  alter- 
nately holding  it  in  the  flame  and  pressing  the  hot  glass  against  the 
blade,  to  accumulate  as  much  as  is  needed.  The  bulb  is  next 
blown  by  the  mouth  or  the  elastic  bottle,  and  this  part  of  the  opera- 
tion requires  a  kind  of  skill  which  can  be  acquired  by  practice  alone, 

(d.)   To  Jill  the  ball  with  mercury. 

First  heat  the  mercury  in  a  ladle,  to  drive  off  moisture  and  air ; 
filter  it  by  making  it  pass  through  pin  holes  in  a  paper  depressed  into 
a  wine  glass,  in  the  form  of  a  funnel ;  next  hold  the  ball  over  a  spirit 
or  an  Argand's  lamp,  the  open  end  of  the  tube  being  immersed  in  the 
mercury,  turning  the  ball  to  prevent  fusion  or  collapse,  and  holding  it 
in  the  heat  as  long  as  the  air  continues  to  issue  freely ;  then  withdraw 
it  and  the,  atmosphere  will  raise  a  column  of  mercury  that  will  fill 
the  ball,  one  third  or  one  half.  Now  bring  the  ball  again  over  the 
lamp,  with  the  mercury  exposed  to  the  heat  until  it  boils,  when  the 
metallic  vapor  will  expel  most  of  the  remaining  air ;  on  withdrawing 
it  from  the  heat,  the  mercurial  vapor  will  be  condensed,  and  the  tube 
having  its  open  end  still  immersed  in  the  mercury,  the  latter  will  rush 
in,  and  nearly  or  quite  fill  the  ball. 

(e.)  To  boil  the  mercury,  for  the  purpose  of  expelling  the  remain- 
der of  the  air. 

Tie  a  small  paper  funnel  to  the  open  end  of  the  glass  tube,  hav- 
ing joined  its  edges  by  paste  or  sealing  wax — throw  in  a  small  globule 
of  mercury  to  act  as  a  valve — then  boil  the  mercury,  holding  the 
tube  vertically  over  the  flame  of  the  spirit  lamp,  and  surrounding  the 
tube  with  thick  folds  of  paper,  protecting  the  fingers  still  farther  by  a 
glove. 

(/.)  When  the  mercury  boils  quietly,  and  the  ball  is  readily  filed  on 
being  withdrawn  from  the  heat,  we  presume  that  the  air  is  all  expelled. 


*  If  the  bore  be  very  small,  the  mercury  must  be  introduced  by  the  elastic  gum 
bottle,  by  tying  it  fast — compressing  it  strongly  with  the  hand  to  expel  the  air,  and 
then  allowing  it  to  resume  its  former  shape,  when  a  portion  of  mercury  will  rise 
into  the  tube. 

t  See  American  Journal.  Vol.  IV,  pa.  398,  for  the  method  of  Mr.  Kendal,  a  self- 
fought  artist. 


HEAT  OR  CALORIC.  5- 

After  the  ball  has  been  cooling  for  a  few  minutes,  the  excess  of 
mercury  is  poured  out,  and  the  column  allowed  to  subside. 

Sg.)  To  try  whether  the  range  of  the  mercury  will  be  correct. 
mmerse  the  ball  in  melting  ice  or  snow — the  mercury  should  not 
sink  within  the  ball — immerse  it  in  boiling  water,  or,  which  is  better, 
in  steam.  In  this  case,  the  mercury  should  not  rise  so  high  as  the 
top  of  the  tube  and  these  two  points,  the  freezing  and  the  boiling 
should  fall  higher  or  lower  according  to  the  use  that  is  to  be  made  of 
the  thermometer,  for  measuring  high  or  low  degrees — that  is,  ex- 
tremes of  heat  or  of  cold  ;  if  intended  for  both,  there  should  be 
sufficient  room  both  above  and  below  these  two  points. 

(A.)  If  there  be  not  mercury  enough,  warm  the  ball  in  a  candle, 
and  let  the  column,  as  it  reaches  the  summit,  be  united  to  more  quick- 
silver in  a  wine  glass,  quickly  reversing  and  plunging  the  tube  for  that 
purpose. 

(i.)  If  there  be  too  much  mercury,  let  a  little  of  it  be  expelled,  by 
warming  the  ball,  and  then  in  either  case,  the  mercury  must  be  ad- 
justed as  regards  the  freezing  and  boiling  points,  by  a  new  immer- 
sion in  melting  snow  or  ice  and  in  steam. 

(j.)   To  close  the  tube  to  exclude  the  atmosphere. 

Draw  the  end  of  the  tube  in  two  by  the  blow  pipe,  and  it  will  be  of 
course  hermetically  sealed  ;  then  break  the  fine  point  so  that  it  may  be 
merely  open ;  next  warm  the  ball,  so  that  the  mercury  will  rise  and  fill 
the  entire  tube,  and  just  as  it  is  about  to  issue  from  the  orifice,  things 
being  previously  adjusted  for  that  purpose,  direct  the  blowpipe  flame 
upon  the  point,  and  seal  it ;  if  correctly  done,  the  mercury  will  then  roll, 
backward  and  forward,  without  breaking  the  column  and  without  im- 
pediment. 

(k.)  Final  adjustment  of  the  fixed  points  of  freezing  and  boiling. 

A  new  exposure  to  the  melting  ice  and  to  the  steam  of  boiling 
water,  will  now  give  us,  by  inspection  of  the  top  of  the  mercurial 
column,  the  important  points  of  freezing  and  boiling  water,  which 
must  be  marked  on  the  glass  by  a  diamond  or  a  file. 

(/.)  Graduation  of  the  instrument. — The  space,  between  freezing 
and  boiling  water,  is  now  to  be  divided  into  one  hundred  and  eighty 
equal  parts;  freezing  water  will  be  32  and  boiling  water  212°. 

This  division  is  arbitrary.  It  was  adopted  by  Fahrenheit  of  Am- 
sterdam, after  whom  the  thermometer,  thus  graduated,  was  called.  The 
0  of  this  scale  indicated  the  greatest  cold  observed  in  Iceland,  and  it 
was  supposed  to  be  as  great  as  would  probably  ever  occur  in  philo- 
sophical experiments.  ^The  scale  is  extended  above  boiling  water  to 
any  desired  degree,  and  below  0,  by  numbers  reckoned  the  opposite 
way,  which  are  considered  as  minus  degrees  and  marked  with  the 
correspondent  arithmetical  sign,  while  the  degrees  above  0  are  written 
without  any  sign. 


5S  HEAT  OR  CALORIC. 

(m.)  Other  points  usually  marked  on  the  scale. — Blood  heat  is? 
marked  98°  for  the  human  subject ;  fever  heat  112° ;  the  mean  sum- 
mer heat  of  the  day  light  in  temperate  climates,*1  76° ;  ether  boils  at 
98°;  alcohol  176J;  mercury  656G,f 

(n.)   Other  scales  used  in  different  countries. 

As  the  division  of  a  thermometrical  scale  is  entirely  arbitrary,  it 
varies  in  different  countries.  In  the  thermometer  of  Reaumur  freez- 
ing water  i&  0  and  boiling  water  80°, 

In  Spain  and  Italy,  this  thermometer  is  still  used ;  but  in  France, 
since  the  revolution,  Reaumur's  has  been  discarded,  and  that  of  Cel- 
sius adopted,  under  the  name  of  thermometre  centigrade,  in  which 
freezing  water  is  G,  and  boiling  water  100°.  To  reduce  the  degrees 
of  Fahrenheit  to  those  of  the  centigrade,  substraet  32,  then  multiply 
by  5  and  divide  the  product  by  9y  because  each  degree  of  Celsius 
=  f  of  l°of  Fahr. 

In  converting  the  centigrade  degrees  into  those  of  Fahrenheity 
double  the  centigrade  number,  subtract  y1^,  then  add  the  constant 
number  32.  Thus,  10°  cent.  X2=20-  rV=20  -2  =  18  +  32=  50°. 

To  convert  the  degree  of  Fahrenheit  into  those  of  Reaumur,  sub- 
tract 32°,  multiply  the  remainder  by  4  and  divide  the  product  by  9  : 
or,  the  reverse,  that  is,  multiply  the  Reaumur  degree  by  9,  divide  by 
4  and  add  32. { 

Mr.  Murray  proposed  another  division  of  the  thermometrical  scale ; 
namely,,  into  one  thousand  degrees,  counting  from  —  39°,  the  freezing 
point  of  mercury,  to  672°,  its  supposed  boiling  point.  The  advantages 
proposed,  are  a  more  minute  division,  the  avoiding  of  negative 
degreesand  fractional  parts,  &,c.f 

Thermometrical  scales  are  often  compared,  by  drawing  a  diagram; 
to  exhibit  them  side  by  side,  when  any  line  drawn  at  right  angles  to 
the  scale  will  cut  the  correspondent  degrees,  which  may  thus  be  read 
by  inspection. 

In  Russia,  De  Lisle's  thermometer  has  been  adopted ;  in  thaty 
freezing  water  is  150°,  and  boiling  water  or  melting  snow  is  0  ;  a  very 
awkward  division. 

(0.)  Principle  of  the  graduation. 

This  is  founded  upon  the  fact  that  the  temperature  of  freezing 
water  and  of  melting  snow  or  ice  is  the  same,  all  the  world  over ; 
and  that  pure  water  (the  pressure  of  the  atmosphere  being  the  same} 
boils  every  where  at  the  same  temperature. 

*  Probably  too  high.  f  Murray's  El.  6  ed.  Vol.  T.  p.  103. 

\  Because  the  zero  of  Fahrenheit's  thermometer  is  32°  lower  than  that  of  the  cen- 
tigrade or  Reaumur.  Before  reduction,  we  must  therefore  subtract  32°  from  the 
Fahrenheit  degree,  or  add  it  to  that  of  Reaumur,  or  the  centigrade. 

§  See  Murray,  2  ed.  Vol.  I.  p.  139.  672°  was  then  admitted  as  the  boiling  point 
of  mercury.  For  other  modes  of  graduation,  see  Ferg.  Lect.  Vol.  I,  p.  181.  an<H 
Cavallo's  Philos.  Vol.  Ill,  pp.  19,  20. 


HEAT  OR  CALORIC.  59 

The  thermometer  ought  therefore  to  be  graduated,  when  the  ba- 
rometer is  at  the  medium  pressure,  or  a  proper  allowance  should  be 
made  for  the  variation.* 

(p.)    Correspondence,  of  thermometers. 

All  thermometers,  accurately  made  upon  these  principles,  will  cor- 
respond, however  different  in  size  or  form.f 
1.)    Choice  of  fluids. 

[ercury  from  its  mobility,  cleanness,  beauty,  nearly  equable  ex- 
pansion by  heat,  great  sensibility  to  that  agent,  and  the  wide  differ- 
ence between  its  boiling  point,  -f  656°  J  and  —39°  its  freezing  point, 
is  generally  used  ;§  oil  is  viscid  and  water  very  limited  in  its  range,  be- 
sides its  unequal  contraction  between  40°  and  32°. 

Alcohol  tinged  with  carmine,  is  used  for  intense  cold,  but  cannot 
be  used  for  heats  above  176°,)|  nor  quite  so  high,  on  account  of  its 
unequal  expansion  near  the  boiling  point ;  while  in  sensibility  it  is 
much  inferior  to  mercury. 

!r.)  Imperfections  of  the  thermometer. 
t  does  not  give  the  result  instantly ;  there  is  some  loss  of  tempera- 
ture before  the  effect  can  be  observed  ;  it  gives  no  information  as  to 
the  absolute  heat,  reckoning  from  the  real  zero ;  it  indicates  only  rel- 
ative heat,  or  heat  compared  with  some  known  degree,  just  as  marks 
may  be  placed  on  the  links  of  a  chain,  whose  terminations  are  con- 
cealed. We  know  not  the  beginning  or  the  end  of  heat ;  but  this  is 
not  the  fault  of  the  thermometer :  the  range  of  the  thermometer  is 
necessarily  limited  between  the  freezing  and  the  boiling  points  of 
the  fluid  with  which  it  is  filled. 

&.)   Uses  of  the  thermometer. 
o  accurate  knowledge  of  the  laws  of  heat  could  have  been  ob- 
tained without  it ;  hence  the  observations  of  the  ancients  on  heat  are 
of  little  value. 

For  philosophical  purposes,  it  is  indispensable.  It  is  of  use  to  a 
physician,  in  observing  the  phenomena  of  disease,  as  of  fever  and 
inflammation  and  in  experiments  on  animal  life,  &ic. 

*  See  Phil.  Trans.  1777,  for  the  rules  of  the  Royal  Society;  also  Phil.  Trans,  abr. 
IV.  1.  for  Newton's  rules.  See  also  Martine,  on  heat  and  thermometers,  and  Eng- 
iish  Jour.  Science,  Vol.  VII.  p.  183,  Chevalier  Landriani. 

t  For  various  causes  of  disagreement,  see  Cordier's  Essay  on  Temp,  of  the  Earth, 
p.  143. 

t  This  point  is  stated  by  Irvine  to  be  672°  of  Fahr.  (Murray,  I.  153.);  662°  Petit 
and  Dulong ;  656°  Crighton,  Glasgow ;  mean  of  the  three,  663^°.— Hen.  9th  ed. 
Vol.  I.  p.  101. 

§  Its  boiling  point  is  higher  than  that  of  any  permanent  fluid,  and  its  freezing 
point  lower  than  that  of  any  fluid,  except  alcohol  and  ether.  Between  32°  and  212°, 
its  expansion  is  almost  perfectly  uniform,  and,  although  at  higher  temperatures  its 
expansion  goes  on  in  an  increasing  ratio,  glass  has,  within  the  above  limits,  the  same 
ratio,  and  therefore  there  is  no  practical  error.—  Turner,  p.  28. 

ij  This  is  its  boiling  point  when  its  specific  gravity  is  820,  water  being  1000. 


60  HEAT  OR  CALORIC. 

For  medical  and  chemical  purposes,  the  bulb  should  be  naked, 
with  a  part  of  the  tube  projecting  below  the  scale. 

It  has  important  uses  to  a  gardener,  as  in  observing  the  temperature 
in  hot  houses,  and  the  heat  adapted  to  sowing  and  planting. 

It  is  useful  at  sea,  as  in  the  gulf  stream  where  the  water  is  warmer 
than  the  mean ;  also  in  approaching  land,  and  in  coming  on  soundings 
or  shoals,  and  near  icebergs,  where  the  temperature  always  changes 
and  grows  colder.* 

It  is  important  to  travellers  in  observing  climates ;  to  many  artists 
in  regulating  their  processes,  and  to  all  persons  in  observing  the  weath- 
er, and  in  regulating  the  heat  in  their  apartments,  in  baths,  &tc. 

(t.)  Varieties  of  thermometers. — The  principal  are — the  self-re- 
gistering, of  which  Six's  is  the  most  remarkable;  the  air,  the  spirit, 
the  water,  and  the  mercurial  thermometer.  Wollaston's  for  measur- 
ing heights,  is  a  very  delicate  instrument,  which  will  be  mentioned 
again. 

Thermometers  are  made  of  various  form  and  graduation,  sometimes 
with  glass  scales  for  immersion  in  acids,  with  naked  balls,  &tc.  They 
are  often  in  pendent  boxes,  or  in  cases  which  shut  for  travelling. 

Laboratory  thermometer. 


"  The  thermometers  used  in  laboratories,  are 
usually  constructed  so  as  to  have  a  portion  of  the 
wood,  or  metal,  which  defends  them  from  inju- 
ry, and  receives  the  graduation,  to  move  upon  a 
hinge,  as  in  the  accompanying  figure. 

"  This  enables  the  operator  to  plunge  the  bulb 
into  fluids,  without  introducing  the  wood  or  met- 
al, which  would  often  'be  detrimental  either  to 
the  process  or  to  the  instrument,  if  not  to  both. 

"  The  scale  is  kept  straight,  by  a  little  bolt  on 
the  back  of  it,  when  the  thermometer  is  not  in 
use." — Dr.  Hare. 


o 


*  The  thermometer  is  regularly  used  on  board  of  ships  of  war,  and  its  indications 
are  recorded  once  or  twice  a  day.  Not  only  does  the  water  always  grow  colder  or 
coming  upon  soundings,  but  generally  the  air  grows  colder  as  we  approach  land. 
(See  Dr.  John  Davy's  observations  in  the  Journals.) 


HEAT  OR  CALORIC. 


61 


Difference  between  an  air  thermometer  and  a  differential  thermo- 
meter, illustrated  upon  a  large  scale. 

"  The  adjoining  figure  represents  an  in- 
strument, which  acts  as  an  air  thermome- 
ter, when  the  stopple  S  is  removed  from 
the  tubulure  in  the  conical  recipient  R ; 
because  in  that  case,  whenever  the  densi- 
ty of  the  atmosphere  varies  either  from 
changes  in  temperature,  or  barometric 
pressure,  the  extent  of  the  alteration 
will  be  indicated  by  an  increase  or  di- 
minution of  the  space  occupied  by  the 
air  in  the  bulb  B,  and  of  course  by  a 
corresponding  movement  of  the  liquid 
in  the  stem  T.  But  when  the  stopple 
is  in  its  place,  the  air  cannot,  within 
either  cavity  of  the  instrument,  be  af- 
fected by  changes  in  atmospheric  pres- 
sure :  nor  can  changes  of  temperature, 
which  operate  equably  on  both  cavities, 
produce  any  movement  in  the  liquid  which 
separates  them.  Hence,  under  these  cir- 
cumstances, the  instrument  is  competent 
to  act  only  as  a  differential  thermometer." 

Dr.  Hare. 
Self-registering  thermometer. 

"  This  figure  represents  a  self-registering 
thermometer." 

"  It  comprises  necessarily  a  mercurial  and  a 
spirit  thermometer,  which  differ  from  those  or- 
dinarily used,  in  having  their  stems  horizontal, 
and  their  bores  round,  also  large  enough  to  ad- 
mit a  cylinder  of  enamel,  in  the  bore  of  the 
spirit  thermometer,  and  a  cylinder  of  steel,  in 
the  bore  of  the  mercurial  thermometer.  Both 
the  cylinder  of  enamel  and  that  of  steel,  must 
be  as  nearly  of  the  same  diameters  with  the 
perforations,  in  which  they  are  respectively  sit- 
uated, as  is  consistent  with  their  moving  freely, 
in  obedience  to  gravity,  or  any  gentle  impulse." 

"  In  order  to  prepare  the  instrument  for  use,  it 
must  be  held  in  such  a  situation,  as  that  the  ena- 
mel may  subside  as  near  to  the  end  of  the  al- 
coholic column  as  possible,  yet  still  remaining 
within  this  liquid." 


£2  HEAT  OR  CALORIC. 

"  The  steel  must  be  in  contact  with  the  mercury,  but  not  at  all  mer- 
ged in  it." 

"  Under  these  circumstances,  if,  in  consequence  of  its  expansion, 
by  heat,  the  mercury  advance  into  the  tube,  the  steel  moves  before 
it ;  but  should  the  mercury  retire,  during  the  absence  of  the  observer, 
the  steel  docs  not  retire  with  it.  Hence,  the  maximum  of  tempera- 
ture, in  the  interim,  is  discovered  by  noting  the  graduation  opposite 
the  end  of  the  cylinder  nearest  the  mercury.  The  minimum  of  tem- 
perature is  registered  by  the  enamel,  which  retreats  with  the  alcohol 
when  it  contracts ;  but,  when  it  expands,  does  not  advance  with  it. 
The  enamel  must  retire  with  the  alcohol,  since  it  lies  at  its  margin, 
and  cannot  remain  unmoved  in  the  absence  of  any  force  competent 
to  extricate  it  from  a  liquid,  towards  which  it  exercises  some  attrac- 
tion. But,  when  an  opposite  movement  takes  place,  which  does  not 
render  its  extrication  from  the  liquid  necessary,  to  its  being  stationary, 
the  enamel  does  not  accompany  the  alcohol.  Hence  the  minimum 
of  temperature,  which  may  have  intervened  during  the  absence  of 
the  observer,  is  discovered,  by  ascertaining  the  degree  opposite  the 
end  of  the  enamel  nearest  to  the  end  of  the  column  of  alcohol." — 
Dr.  Hare. 

3.  WEDGWOOD'S  PYROMETER. 

(a.)  This  instrument  is  constructed  on  a  different  principle  from, 
that  of  other  pyrometers  and  thermometers ;  still  it  affords  no  ex- 
ception or  contradiction  to  the  law  of  expansion ;  it  depends  on  a 
permanent  contraction  of  certain  cylinders  of  clay  in  consequence 
of  the  application  of  heat,  which  operates  by  expelling  water  and 
eventually  by  causing  a  chemical  union  of  the  alumina  and  silex  of 
the  clay  pieces,  and  an  approximation  to  the  condition  of  porcelain. 

(6.)  The  cylindrical  pieces  of  clay*  are  modelled  and  thrust 
through  a  mould,  a  little  flattened  on  one  side — baked  gently  to  ex- 
pel air  and  moisture,  made  to  fit  at  0  between  two  converging  rules 
of  brass,  twenty  four  inches  long,  distant  .at  the  wider  end  .5  of  an 
inch,  and  .3  at  the  other,  and  screwed  to  a  brass  plate,  divided  into 
two  hundred  and  forty  equal  parts  or  degrees,  each  of  which  is  there- 
fore one  tenth  of  an  inch. 

Jc.)  Zero  of  the  scale  is  1077^  of  Fahrenheit ,  and  indicates  a  full 
heat,  visible  in  the  day  light. 

(d.)  Each  Wedgwood  degree  corresponds  to  130°  Fahr. 

(e.)   To  convert  Wedgwood  degrees  into  Fahrenheit  degrees; 

Multiply  the  Fahrenheit  degree  by  130  and  add  1077.5  ;  thus  the 
two  may  be  compared. 


*  The  clay  used  by  Mr.  Wedgwood,  was  from  Cornwall.     See  Phil.  Trans.  Vols. 
72,  74,  and  76. 


HEAT  OR  CALORIC.  63 

(/•)  Wedgwood  original  pieces  are  not  now  attainable, — at  least 
not  the  same  that  Mr.  Wedgwood  used,  the  bed  of  clay  being  ex- 
hausted. 

Mr.  Wedgwood  connected  his  pyrometer  with  the  common  ther- 
mometer, by  the  expansion  of  cylindrical  pieces  of  silver  measured 
in  a  groove  of  earthern  ware  similar  to  his  scale. 

Henry  states  that  the  greatest  degree  of  heat  observed  was  1 85-° 
W.  25127Fahr.— Appendix. 

(g.)  Wedgwood?  s  pyrometer  is  the  only  one  for  measuring  high  fur- 
nace heat. 

(h.)  The  highest  degree  of  Wedgwood  corresponds  to  32.277 
Fahr. 

(i.)  The  greatest  range  of  observations  made  by  Fahrenheit's  ther- 
mometer does  not  exceed  the  -^  part  of  that  ascertained  by  Wedg- 
wood. 

There  is  no  measure  for  the  highest  heat ;  Dr.  Hare's  compound 
blow  pipe  readily  melts  all  porcelains  and  other  earthy  compositions, 
more  refractory  than  Wedgwood's  clay  pieces. 

(j.)  Artificial  clay  pieces  may  be  made,  but  little  dependence  is 
now  placed  upon  these  earthy  compositions  for  pyrometers ;  for,  Sir  J. 
Hall  has  ascertained,  that  a  mild  heat  long  continued,  has  a  similar 
effect  in  causing  them  to  contract,  with  a  sudden  and  violent  one. 
Mr.  Faraday*  considers  Daniell's  pyrometer  as  the  best.f 

II.  DISTRIBUTION  OF  TEMPERATURE  AND  COMMUNICATION  OF 
HEAT. 

1.  CALORIC  CONSTANTLY  TENDS  TO  AN  EQUILIBRIUM. 

This  tendency  is  never  effectual  on  a  great  scale,  because  of  the 
operation  of  numerous  disturbing  causes ;  the  equilibrium  is,  to  a 
good  degree,  attainable  in  a  limited  and  confined  space,  as  in  a  close 
room  -y  J  in  such  a  situation,  a  thousand  bodies  of  different  temperature 
will  ultimately  assume  nearly  or  quite  the  same  temperature,  and  the 
thermometer,  when  applied  to  them  severally,  ascertains  the  fact. 

(a.)  Radiation  and  actual  contact  both  contribute  to  the  effect. — 
At  high  temperatures,  radiation  is  the  most  effectual,  but  actual  contact 
is  most  efficient  at  low  degrees  of  heat. 

(b.)   Caloric  radiates  through  a  vacuum. 

Therefore  a  medium  is  not  necessary  to  its  transmission,  a  body  in 
a  vacuum  cools  about  half  as  fast  as  in  the  air. 

2.  THE    ATMOSPHERE    IS    VERY    UNEQUALLY    HEATED. 


*  Chem.  Manip.  pa.  146. 

t  See  Quarterly  Jour,  of  Sci.  XI.  309. 

t  Even  in  such  circumstances  there  is  generally  a  sensible  difference  between 
the  temperature  of  the  floor  and  of  the  ceiling  of  the  room.  See  Mr.  Marcus  Bull's 
account  of  his  experiments  on  the  heat  afforded  by  different  kinds  of  fueL 


64  HEAT  OR  CALORIC. 

It  is  most  heated  at  the  earth's  surface,  and  in  a  rapidly  decreasing 
series,  (perhaps  even  a  geometrical  one,)  as  we  ascend, 
(a.)  Line  of  perpetual  congelation. 

At  a  certain  elevation  in  the  atmosphere,  it  freezes  in  some  part  of 
every  day  in  the  year ;  and  at  a  height  not  less  than  three  miles,  it 
would  freeze  water,  at  all  times,  in  every  climate,  that  surrounds  our 
earth. 

(b.)  Height  of  the  line  of  perpetual  congelation. 
At  the  equator  it  is  15577  feet,  as  ascertained  by  Mr.  Bouguer  by 
actual  observation  on  Pinchinca,  one  of  the  peaks  of  the  Andes ;  in 
lat.  45°  it  is  9016  feet;  in  lat.  70°  it  is  1557  feet;  in  lat.  80°  it  is 
120  feet ;  and  at  the  pole,  it  is  nearly  coincident  with  the  earth's  sur- 
face. Most  of  these  numbers  were  obtained  by  calculation,  upon  a 
principle  explained  by  Mr.  Kirwan.* 

(c.)  Causes  of  the  increase  of  cold  in  the  higher  regions  of  the  at- 
mosphere.— The  sun's  rays  do  not  heat  the  air  while  passing  through  it; 
they  heat  the  earth  first,  and  this  heats  the  air  by  actual  contact. 
As  we  ascend,  the  capacity  of  the  air  for  heat  increases  in  an  arith- 
metical, while  its  density  diminishes  in  a  geometrical  ratio ;  hence,  it 
requires  more  heat  to  produce  a  given  temperature.  Among  the 
minor  causes,  may  be  mentioned  the  absence,  in  a  great  degree  at  high 
elevations,  of  animal  and  vegetable  life,  of  fermentation,  of  combus- 
tion, respiration  and  putrefaction,  all  of  which  generate  heat. 

(d.)  Snow  is  in  every  climate,  perpetual  on  high  mountains. — 
Because  their  tops  pierce  the  regions  of  perpetual  cold,  and  snow 
once  remaining  the  year  round,  will  continue  ;  the  sun  cannot,  in  a 
second  summer,  melt  what  it  has  failed  to  melt  in  a  first. 

Any  commencement  of  warming  there,  by  the  sun's  rays,  before  the 
first  snow  fell,  would  have  been  very  transient,  because  ventilation 
would  soon  begin,  as  the  lateral  columns  of  air,  not  over  the  moun- 
tain ridges  or  top,  would  not  be  heated  at  that  elevation,  and  being 
heavier  would  rush  in  upon  them  on  all  sides,  and  therefore  the  sur- 
face there  would  never  become  warm. 

(e.)  Effect  of  the  winds  on  the  term  of  perpetual  cold. 
They  raise  it  by  mingling  warm  air  with  the  cold  ;  if  there  were 
no  winds,  perpetual  cold  would  no  where,  be  over  a  mile  above  the 
earth's  surface. — Dr.  Black's  Lectures. 

*  The  mean  temperature  at  the  equator  and  in  any  parallel  of  latitude,  being  ascer~ 
tained  by  observation,  we  take  the  difference  between  each  of  these  two  numbers  and 
the  freezing  point ;  the  height  of  the  term  of  perpetual  congelation  at  the  equator 
is  also  ascertained  by  observation  ;  the  number  to  be  found,  is  the  height  of  the 
same  term  in  any  parallel  of  latitude ;  the  proportion  will  be,  as  52°  (84°  mean 
temp.— 32°  =  52)  the  number  at  the  equator,  is  to  15.577  the  height  of  the  term  of 
perpetual  congelation  there,  so  is  40°. 3  the  number  at  28°  of  lat.  (72°.3  mean  temp. 

32°  — 40°.3=  third  term,)  to  12.072  the  height  of  the  term  of  congelation  there, 

and  so  for  any  other  latitude.  Due  allowance  must  of  course  be  made,  for  the  el- 
evation of  the  country  above  the  sea,  for  its  mountainous  or  level  surface  and  for  va- 
rious other  causes,  which  would  influence  its  climate. 


HEAT  OR  CALORIC.  G5 

It  results  therefore,  from  all  our  knowledge,  that  our  atmosphere 
is,  throughout  its  whole  extent,  in  every  climate,  and  in  every  season, 
a  region  of  unmitigated  cold,  excepting  the  small  spheroidal  portion 
which  is  nearest  to  the  earth — distant  from  it  less  than  three  miles  in 
the  torrid  climates ;  rapidly  approaching  the  earth  in  the  other  climates, 
and  almost  touching  it  at  the  poles.  Therefore,  between  the  planets 
and  in  space  generally,*  it  is  probable,  that  the  temperature  is  very  low. 

3.  COMMUNICATION  OF  HEAT — CONDUCTION,  RADIATION. 

A.  The  name  of  CONDUCTION  is  given  to  the  slow  passage  of 
Caloric  through  the  substance  of  bodies  and  to  its  cause  ;  that  of 
RADIATION,  to  the  instantaneous  passage,  from  surfaces,  and  through 
a  transparent  medium,  and  also  to  the  cause  of  it. 

(b.)  The  conducting  powers  of  bodies  arc.  widely  different. — If  a 
cylinder  of  metal  and  one  of  glass,  of  the  same  size,  be  held  by  the  fin- 
gers in  the  fire,  the  metal  will  feel  hot,  and  perhaps  become  intolera- 
ble to  the  touch,  while  the  glass  will  communicate  little  or  no  heat. 

Those  bodies  which  in  their  ordinary  state  feel  coldest  to  the  touch, 
are  the  best  conductors,  and  vice  versa  ;  hence,  some  bodies  are  sup- 
posed to  be  naturally  cold,  as  for  instance,  marble ;  others  naturally 
warm,  as  woollen ;  but  this  is  an  error.  They  may  have  the  same  tem- 
perature by  the  thermometer,  and  still  impart  very  different  sensations, 
as  will  be  perceived  by  laying  one  hand  on  fire  brick  and  the  other 
on  trapf  rock  ;  or  more  strikingly,  one  hand  on  woollen,  and  the  other 
on  metal,  both  being  of  the  same  temperature  by  the  thermometer. 

When  we  apply  the  hand  to  various  objects  in  our  apartment — "  the 
carpet  will  feel  nearly  as  warm  as  our  body ;  our  book  will  feel 
cold,  the  table  cold,  the  marble  chimney  piece  colder,  and  the  can- 
dlestick colder  still,  yet,  a  thermometer  applied  to  them  will  stand  in 
all  at  nearly  the  same  elevation.  They  are  all  colder  than  the  hand ; 
but  those  that  carry  away  caloric  most  rapidly,  excite  the  strongest 
sensations  of  cold."J 

(c.)  Bodies ,  taken  in  classes,  conduct  better,  the  more  dense  they 
are,  and  vice  versa. 

Metals  conduct  better  than  any  other  bodies,  but  there  is  a  differ- 
ence among  them,  for  instance,  copper  and  tin  conduct  better  than 
lead  and  platina. 

The  following  metals  conduct  heat,  nearly  in  the  order  in  which 
they  are  named. 

Silver,  Gold,  Copper,  Tin, — nearly  equal. 

Platina,  Iron,  Steel,  Lead, — much  inferior  to  the  others. 

(d.)  Bodies  conduct  heat  worse,  the  more  spongy  and  divided  their 
parts  are. 

*  Except  perhaps  near  the  innumerable  suns. 

t  Or  any  stone  ; — trap  is  here  mentioned,  because  it  is  a  very  good  conductor  of 
its  class.  t  Turner's  Chemistry,  pa.  11,  first  Edition. 

9 


66  HEAT  OR  CALORIC. 

Iron  filings  are  worse  conductors  than  an  iron  bar  of  the  same 
weight ;  saw  dust  is  worse  than  the  solid  wood. — Rumford.  The 
cause  probably  is  the  intervention  of  air  between  their  parts ;  air  being 
a  very  bad  conductor. 

(e.)  Stones  are  next  to  metals. 

Crystalline  stones  conduct  better  than  mechanical  aggregates,  e.  g. 
trap  better  than  sandstone ;  the  difference  is  evident  to  the  touch, 
and  it  appears  also,  from  their  widely  different  power  of  condensing 
the  atmospherical  vapor ;  a  trap  rock  will  be  wet  from  this  cause, 
while  one  of  sandstone  will  be  dry. 

Earth  and  sand  conduct  worse  than  stones.  At  the  siege  of  Gib- 
raltar, in  the  American  war,  red  hot  balls  were  carried  from  the  fur- 
naces to  the  bastions,  in  wooden  wheelbarrows,  by  merely  placing 
a  layer  of  sand  beneath  them. 

(/*.)  Bricks  are  worse  conductors  than  stones. 

Because  they  are  full  of  pores  containing  air ;  they  are  used  to  im- 
pede the  escape  of  heat,  as  in  the  lining  of  chemical  furnaces  of  iron,* 
which,  while  they  are  melting  brass  or  cast  iron  within,  can  be  safely 
touched  by  the  hand  without. 

A  hot  brick  or  plank,  wrapped  in  flannel,  retains  its  heat  a  long  time ; 
it  is  used  for  warming  the  feet,  in  winter  travelling,  and  in  sickness. 

(g.)   Glass  is  a  very  bad  conductor. 

When  thick,  it  cracks  from  sudden  heating  or  cooling,  but,  if  thin, 
it  bears  sudden  changes  of  temperature  very  well.  The  reason  is. 
that  being  a  bad  conductor,  when  one  side  is  hot,  it  swells,  and  the 
colder  side  is  strained,  and  often  gives  way. 

(h.)  Dry  wood  is  a  bad  conductor. 

Hence,  it  is  used  for  handles  of  metallic  instruments,  as  of  ladles, 
soldering  irons,  tea  and  coffee  pots,  gridirons,f  &c.  It  is  also  a  bad 
conductor  of  electricity.  "  Common  bone,  whale  bone,  ivory  and 
porcelain,"  are  very  imperfect  conductors,  especially  when  compar- 
ed with  metals. 

(i.)  Charcoal  is  a  very  bad  conductor. — It  may  be  held  by  the  fin- 
gers, within  an  inch  or  less,  of  the  part  which  is  red  hot ;  it  is  used 
in  wine  coolers,  with  double  sides,  to  prevent  the  entrance  of  heat, 
and  it  is  mixed  with  clay  and  other  materials  for  bricks  and  crucibles, 

(/.)  Feathers,  silk,  wool,  hair,  and  down,  are  still  worse  con- 
ductors.— Hence  they  are  so  effectual  in  preserving  animal  heat,  both 
in  the  animals  naturally  invested  with  them,  and  in  the  human  race 
who  wear  them  for  clothes.  They  are  not  naturally  warm,  but  pre- 


*  And  in  the  iron  furnaces  now  used  in  this  country,  for  burning  anthracite  coal. 

t  Worsted,  being  a  very  bad  conductor,  workmen  who  have  occasion  to  handle 
substances  which  are  either  hotter  or  colder  than  is  agreeable,  frequently  wear 
gloves  made  of  this  substance. — L.  u.  K. 

At  Wallingford,  Con.  pewter  tea  pots  are  now  made,  with  hollow  metallic  handles, 
and  they  do  not  often  become  inconveniently  hot.  because  they  contain  imprisoned  air 


HEAT  OR  CALORIC.  07 

serve  our  animal  heat  from  escaping.  Loose  garments  are  warmer 
than  those  that  are  tight,  because  they  imprison  the  air,  and  the  same 
weight  of  clothing,  in  two  or  more  thicknesses,  is  warmer  than  in  one  ; 
hence  the  advantage  of  lining  and  quilting,  as  in  comfortables,*  down 
coverlets,  &c. 

The  finer  the  fibres,  the  more  effectual  they  are ;  therefore  an- 
imals are  provided  with  fur  which  is  finest  in  the  coldest  countries, 
and  in  winter  it  is  finer  than  in  summer  ;  in  aquatic  birds  and  am- 
phibia, the  fur  and  feathers  are  finer  than  in  the  terrestrial  races. 
Fine  wooled  sheep  would,  in  torrid  climates,  become  coarse  wooled. 
Some  covering  of  this  nature  is  necessary  even  in  hot  climates,  to 
protect  animals  from  the  copious  dews  and  rains,  and  other  atmos- 
pherical changes. 

(k.)  Ice  is  a  bad  conductor  and  snow  still  worse. — Hence  ice 
retards  the  congelation  of  the  water  below;  snow  protects  the 
grass  and  grain  from  destruction  by  severe  cold ;  it  differs  from  ice 
because  it  imprisons  air  in  its  cavities.  When  the  air  in  Siberia  was 
—  70°,  the  earth  under  the  snow  was  only  32^.  Snow  huts  or  holes 
so  often  used  by  travellers  in  cold  countries,  as  in  the  north  western 
regions  of  America,-)-  are  very  warm. 

(L.)  FLUIDS^  ARE  WORSE  CONDUCTORS  THAN  ANY  SOLIDS. 

The  common  impressions  on  this  subject  are  erroneous ;  fluids 
are  usually  heated  at  bottom,  and  the  change  of  specific  gravity  throws 
them  into  currents ;  warm  currents  flow  upward  and  cold  down- 
ward, and  thus  the  heat  is  soon  diffused.  "  If  a  thermometer  be 
placed  at  the  bottom  and  another  at  the  top  of  a  tall  jar,  the  heat  be- 
ing applied  below,  the  upper  one  will  begin  to  rise  almost  as  soon  as 
the  lower." — Turner. 

Heat,  applied  at  the  surface,  travels  downward  very  slowly.  Mr. 
Murray  provided  a  cylindrical  vessel  of  ice  ;§  he  froze  a  thermometer 
in  at  right  angles  to  the  side,  and  near  the  top,  filled  the  vessel  with 
oil  and  applied  heat  on  the  surface  ;  there  was  no  conducting  pow- 
er in  the  sides, ||  but  the  thermometer  proved  that  the  heat  did  travel 
down,  although  with  extreme  tardiness  :  therefore  fluids  are  not  non 
conductors,  but  only  very  bad  conductors. 

In  solids,  the  particles  are  stationary  or  only  recede  from  each 
other,  and  the  heat  travels ;  in  fluids,  their  own  particles  travel  and 
transport  the  heat. 

(M.)  GASES,  AIR,  VAPORS,  AND  ALL  AERIFORM  FLUIDS,  ARE  THE 

WORST  CONDUCTORS  KNOWN. 

*  A  name  given  in  this  country,  to  a  bed  covering  made  in  the  manner  described  in 
the  text.  t  Captain  Parry,  and  Am.  Jour.  Vol.  X11I,  p.  391. 

t  Except  mercury  and  melted  metals  generally. 

§  Nicholson's  Journal,  8vo.  Series,  Vol.  I,  p.  241. 

|j  Ice  is  a  conductor,  although  a  bad  one,  at  all  temperatures  below  32°  ;  as  it  melts 
at  that  degree,  it  follows  that  in  this  experiment,  any  heat  derived  from  the  hot  fluid, 
would  go  only  to  melt  the  ice,  but  would  not  travel  down  its  sides. 


68  HEAT  OR  CALORIC. 

Here  again  the  common  impressions  are  erroneous.  Air  is  com- 
monly used  to  cool  bodies,  but  it  is  air  in  motion,  not  air  at  rest.  Air 
in  motion  cools  hot  bodies  rapidly,  because  new  particles  come  every 
moment  into  contact  with  the  heated  body.  Air  confined,  impedes 
the  progress  of  heat  more  than  any  other  body,  because  it  is  among 
the  very  worst  of  conductors. 

Double  windows,  double  walls,  furred*  walls,  all  contribute  very 
much  to  keep  houses  warm  in  winter  and  cool  in  summer,  because 
the  parallel  surfaces  imprison  the  air  between  them. 

(n.)  Change  of  temperature  instantly  disturbs  the  statical  pressure 
of  the  air  and  produces  currents. — A  common  fire,  a  lamp,  a  candle, 
and  all  furnaces,  are  examples. 

When  the  fire  is  active,  there  are  opposite  currents  in  a  warm  room, 
of  cold  air  along  the  floor,  and  of  warm  air  along  the  ceiling.  The 
currents  divide  at  an  open  door  ;  hot  air  passes  out  above,  and  cold 
air  blows  in  below,  as  may  be  seen  by  placing  the  flame  of  a  candle  in 
the  door  ;  above,  it  will  point  outward  ;  below,  inward,  and .  at  an  in- 
termediate point,  it  will  be  perpendicular ;  or,  three  candles  may  be 
used  at  the  same  time,  and  the  effects  will  be  as  stated  above :  the 
hotter  the  room  and  the  colder  the  external  air,  the  more  striking  will 
be  the  effect. 

(0.)  The  best  air  for  respiration  is  usually  along  the  floor. — Peo- 
ple falling  from  suffocation,  in  bad  air,  often  recover  on  reaching  the 
floor  ;  a  principal,  although  not  perhaps  the  sole  reason,  is,  because  the 
deadly  gases  and  vapors,  if  not  specifically  lighter  than  air,  are  usually 
temporarily  so  from  their  rarefaction,  as  they  are  commonly  produced 
either  by  respiration-)-  or  combustion.  A  life  preserver  used  in  fires, 
is  worn  on  the  head,  and  a  projecting  flexible  tube  descends  like  an  el- 
ephant's proboscis,  so  that  the  orifice  or  snout  touches  the  floor,  and 
thus  the  wearer  breathes,  it  may  be,  tolerable  air,  while  that  which 
surrounds  his  head,  would,  if  inspired,  be  noxious  or  perhaps  fatal. 

(p.)  The  current  of  a  chimney  and  of  common  winds,  as  well  as 
monsoons,  trade  winds,  and  even  hurricanes  and  tornados,  depends  on 
the  ascent  of  air  rarefied  by  heat. — Warm  air,  that  is  to  say,  lighter 
air  is  forced  upward  by  colder,  or  in  other  words,  by  heavier  air. 

The  monsoons  of  India  are  produced  by  the  heating  of  the  earth, 
and  consequently  of  the  air,  by  the  sun,  during  his  visit  to  the  northern 
tropic :  the  colder  air,  from  the  ocean  consequently  rushes  in  to  restore 


*  Furred,  a  term  applied  by  the  builders  to  an  interior  wall  in  a  stone  or  brick 
house,  laid  not  upon  tlje  solid  material, but  upon  lath,  which  are  nailed  to  perpendicu- 
lar strips  of  boards  or  plank,  and  these  again  to  billets  of  wood  laid  in  the  masonry ; 
there  is  then  a  space  filled  with  imprisoned  air, 

t  In  bed  rooms,  especially  in  cold  weather,  carbonic  acid  gas,  flowing  rarefied 
from  a  hot  source,  may  afterwards  become  so  chilled,  as  (o  fall  and  prevail  most  near 
the  floor  ;  a  pan  of  cools  or  even  a  lamp  or  ^  candle  may  in  this  manner,  especially 
in  a  small  room,  without  an  open  chimney,  produce  a  noxious  atmosphere. 


HEAT  OR  CALORIC.  69 

the  equilibrium :  during  his  passage  to  the  southern  tropic,  the  process  is 
reversed,  and  the  wind  blows,  for  six  months,  the  other  way. 

Sea  breezes  by  day,  and  by  night,  in  hot  climates,  and  in  hot 
weather  in  temperate  climates,  depend  upon  the  same  principle. 
The  trade  winds  are  caused  by  the  tendency  of  the  cold  currents  to 
restore  the  pressure,  occasioned  by  the  rarefaction  of  the  air,  within 
the  tropics,  from  the  perpetual  presence  of  the  sun  in  that  region. 
Hence,  the  currents  which  the  atmosphere  pushes  in,  from  the  north 
east  and  the  south  east,  are,  at  the  equator,  blended  into  one,  which 
follows  the  apparent  course  of  the  sun.  The  heated  air  which  rises, 
is  in  the  mean  time  diffused  over  the  upper  regions  of  the  atmosphere, 
flows  north  and  south,  is  chilled  >and  condensed,  and  falls  in  the  tem- 
perate and  polar  regions,  to  go  through  the  same  round  again.* 

(q.)  Currents  upward  and  downward,  both  in  gross  and  aerial 
fluids,  produce  a  vast  and  salutary  effect  on  the  comfort  of  the  globe. 

The  warm  ocean  imparts  its  heat  to  the  chilled  land,  of  the  polar 
regions,  and  the  hot  land  of  the  tropical  countries  gives  its  heat  to  the 
water  of  the  cool  ocean  ;  the  monsoons  and  trade  winds  and  common 
winds  produce  a  similar  effect  in  the  atmosphere. f 

Without  currents,  the  atmosphere  would  become  fatally  hot,  in  tor- 
rid, and  fatally  cold  in  frigid  climates;  and  similar  inequalities  in  the 
ocean  and  other  great  waters  would  be  deadly  to  the  aquatic  animals. 

(R.)  RADIATION  OF   HEAT  is  ITS  (apparently)  INSTANTANEOUS 

PASSAGE  THROUGH  TRANSPARENT  MEDIA. 

We  can  perceive  no  progress,  and  therefore  regard  the  passage  as 
instantaneous  :  there  can  be  no  reasonable  doubt  that  it  passes  as  ra- 
pidly as  light. 

(s.)  Caloric  or  heat  radiates  from  the  sun,  from  fires,  and  volca- 
nos,  and  probably  from  all  bodies. — All  our  experience  confirms  this 
statement,  and  particular  experiments  to  prove  it  will  be  mentioned 
hereafter. 

(t.)  Solar  heat  radiates  more  or  less,  through  all  transparent 
media,  whether  solid,  fluid  or  aerial,  and  generally  without  heating 
them  materially.  J 

(u.)  Culinary,  or  artificial  heat  radiates  only  through  air,  and 
other  aerial  fluids,  and  not  through  transparent  solids,  or  transpa- 
rent gross  fluids,  as  water,  alcohol,  fyc. — The  cause  of  this  difference 
is  not  known. 

(v.)   The  transparent  bodies  through  which  artificial  heat  does  not 

*  See  Dr.  Hare's  essay  on  the  gales  of  the  Atlantic  States  of  N.  Ain.Am.  Jour. 
Vol.  V,  p.  352. 

t  Murray,  2d  Edit.  Vol.  I,  p.  276. 

\  The  lower  regions  of  the  air  would  be  quite  as  cold  as  the  upper,  did  they  not 
receive  heat  from  the  earth. 

§  There  is  a  difference  in  this  respect,  among  media;  water  arrests  abgut  half  the 
I'ays,  and  alcohol  more  than  half,  and  of  course  heat  is  acquired  by  these  fluids, 


70  HEAT  OR  CALORIC. 

radiate,  are  heated  by  it,  but  they  derive  little  heat  from  the  solar  rays, 
which  permeate  them  easily. 

For  the  most  important  facts  respecting  the  radiation  of  heat,  see 
the  section  on  the  nature  of  heat  and  light. 

A  few  facts  may  be  added  here. 

(iv.)  Polished  surfaces,  of  all  bodies  that  are  not  transparent,  re- 
flect radiant  solar  heat,  and  do  not  transmit  it.* 

(a?.)  Caloric  not  only  radiates  freely  in  a  vacuum,^  but  it  is  not 
impeded  by  currents  or  agitation  of  the  air. — Winds  do  not  disturb 
sunshine,  and  the  solar  focus  is  equally  distinct  and  powerful,  in  a 
windy  as  in  a  still  day.  Bellows  blowing  across  a  current  of  radiant 
culinary  heat,  do  not  divert  the  rays. 

(Y.)  Surface  has  a  great  effect  on  the  radiation  and  reception  of 
heat  independently  of  the  nature  of  the  material. 

Blackf  and  rough  surfaces,  radiate  and  receive  heat  the  best ; 
bright  and  polished  surfaces,  the  worst.  Glass,  however,  although 
naturally  polished,  radiates  and  receives  heat  very  well,  and  so  do 
paper,  skin,  and  animal  membrane ;  the  latter  radiates  and  receives 
twenty  five  times  as  powerfully  as  polished  metal. 

(2.)  The  radiating  and  absorbing  powers  are  alike  and  equal; 
but  the  radiating  and  reflecting  powers  are  directly  opposed,  and 
are  inversely  as  each  other. — In  a  cubical  vessel  of  tin,  one  of  whose 
sides  was  blackened,  another  papered,  and  another  glazed,  the  radi- 
ation was  in  the  following  proportion — 

from  the  black  side,  100° 

"       "  papered,       -  98° 

"       "  glazed,  -     90° 

"       "  bright  metallic,      -  12°  Leslie. 

(aa.)  The  thermometer  indicates  more  or  less  of  heat,  according  as 
'its  surface  is  blackened,  covered  with  tinfoil  or  other  good  reflector, 
or  is  in  its  natural  state. — For  a  comparative  result,  it  should  be  at 
the  same  temperature,  in  the  beginning  of  different  experiments. 

Jbb.)  All  mirrors  lose  their  power  of  reflecting  heat  if  blackened — 
become  heated. — Glass  mirrors,  not  reflecting  culinary  heat,  do 
reflect  it,  if  covered  with  tin  foil. 

*  In  order  that  this  should  be  strictly  true,  the  solids  must  be  supposed  to  be  per- 
fectly smooth,  of  which  we  have  perhaps  n'o  examples.  Scratched  metallic  surfaces 
receive  and  emit  more  heat,  if  the  scratches  cross  one  another,  than  if  they  are 
parallel ;  the  difference  is  attributed  to  the  formation  of  points,  by  the  intersection, 
through  which  points,  the  heat  more  readily  passes. 

t  As  ascertained  by  Pictet  and  Rumford.  In  the  experiments  of  the  latter  it  per- 
vaded the  Torricellian  vacuum.  Sir  Humphrey  Davy  found  that  a  thermometer 
was  heated  by  radiation,  from  charcoal,  ignited  by  galvanism  in  a  vacuum,  three 
times  as  much  as  it  would  have  been  in  the  air  ;  there  being  no  cooling  effect  from 
currents. 

t  Dr.  Turner  doubts  whether  color  has  any  effect  on  the  absorption  of  heat  unless 
the  latter  is  accompanied  by  light,  in  which  case  he  calls  it  luminous  caloric :  but 
then  he  allows  that  the  effect  is  great. 


HEAT  OR  CALORIC. 


71 


PRACTICAL    QUESTIONS. 

(cc.J  Why  are  black*  clothes  hotter  in  the  summer  and  in  the  sun, 
than  in  the  winter  and  in  the  shade  ? — In  order  to  settle  this  ques- 
tion, it  is  necessary  to  ask  another,  that  is,  in  what  circumstances  will 
the  absorption  exceed  the  radiation  of  heat  ?  This  will  plainly  be  in 
the  summer,  and  the  reverse  will  be  true  in  the  winter. 

(dd.)  Why  do  black  people  endure  heat  better,  and  cold  worse,  than 
white  people  / — The  answer  depends  on  the  same  cause,  taking  into 
view  the  average  animal  temperature. 

(ee.)  Why  should  steam,  which  we  wish  not  to  condense,  be  con- 
veyed in  bright  tubes,  and  vice  versa  ? — Because  such  surfaces  radi- 
ate heat  badly. 

(ff.)  Why  does  a  common  rolled  iron  stove  pipe  diffuse  heat  bet- 
ter than  a  bright  tinned  one  ? — Because  its  surface  is  rough,  and 
therefore  radiates  heat  powerfully,  f 

(&&•)  Why  does  water  keep  hot  longer  in  a  bright  polished  vessel 
than  in  a  dark  and  rough  one  ?  J — The  answer  is  the  same  as  in  ee. 

(M.)    Why  does  water  become  heated  rapidly  in  a  rough  iron 

kettle,  and  slowly  or  not  at  all  in  one  of  bright  copper  ? — The 

answer  is  the  same  as  in  jf,  reception  being  substituted  for  radiation. 

(ii.)  Why  would  an  earthern  ware  tube,  when  gilded,  preserve 
steam  longer  uncondensed,  than  the  same  tube  with  its  natural  sur- 
face, or  than  bright  tinned  iron  ? — Because  the  substance  is  a  bad 
conductor,  and  the  surface  a  bad  radiator. 

(./}•)  Why  does  snow  melt  rapidly  where  the  dirt  is  thrown  upon 
or  mixed  with  it,  as  in  the  travelled  path,  and  slowly,  or  not  at  all, 

*  Quere,  (communicated — )"  Are  black  clothes,  when  worn  in  the  shade  during 
summer,  warmer  or  cooler  than  white  clothes  in  the  same  circumstances  ?"  The 
answer  will  depend  on  the  radiating  and  receiving  power  of  the  surfaces,  and  on  the 
temperature  of  the  air,  compared  with  that  of  the  body. 

i  In  neither  of  these  cases,  is  the  final  cause  assigned ;  it  is  unknown. 

t  Experiment  in  Yale  College  Laboratory,  Nov.  10th.  1826. — A  blackened  and  a 
polished  canister  of  plated  tin  of  the  same  form  and  size,  being  filled  with  water  at 
200° — their  times  of  cooling  were  as  follows. 

Blackened  Canister  cooled 
in  the  1st  12  minutes, 

2d  12 

3d  12 

4th  12 

5th  12 

6th  12 

7th  12 

8th  12 

96  min. 

In  one  hour  and  thirty  six  minutes,  the  blackened  canister  cooled  61°,  during  which 
time  the  polished  one  cooled  but  35°.  (At  two  hours  Trona  the  completion  of  the 
above  experiment*,  viz.  three  hour^  and  thirty  six  minutes  from  the  commencement, 
the  water  in  the  polished  canister  was  still  20°  warmer  than  in  the  blackened  one.) 


Accumulating 

Polished  Canister  cooled 

Dif. 

differences. 

0° 

in  the  1st  12  minutes,      6° 

4° 

4° 

s 

2d  12 

5 

3 

7 

7 

3d  12 

5 

2 

9 

6 

4th  12 

3 

3 

12 

8 

5th  12 

3 

5 

17 

9 

6th  12 

5 

4 

"21 

8 

7th  12 

5 

3 

24 

5 

8th  12 

3 

2 

26 

T°~ 

96  min.            35° 

i 

72  HEAT  OR  CALORIC. 

where  it  is  clean,  and  especially  if  glazed,  by  frozen  rain'} — Because 
snow  is  a  good  reflector,  and  dirt,  from  its  rough  dark  surface,  absorbs 
heat  rapidly. 

(kk.)  Why  on  copper  plates  painted  black,  white,  gray,  fyc.  does 
wax  melt  soonest  on  the  black  and  other  dark  colors,  and  scarcely  at 
all  on  the  white*  when  they  are  exposed  to  the  sun  *? — The  answer 
is  founded  on  the  general  effect  of  colors  on  the  absorption  and  radi- 
ation of  heat. 

(II.)  Why  do  pieces  of  cloth  of  different  colors,  black,  white,  and 
intermediate  shades,  when  laid  on  snow  in  the  sunshine,  sink  into  the 
snow  very  differently,  the  black  deepest,  and  the  white  not  at  all  ? — 
The  answer  is  the  same  as  under  kk. 

(mm.)  Why  in  summer,  is  the  temperature  of  the  earth  several  de- 
grees lower  than  that  of  the  air,  especially  in  a  clear  night  ? — It  is 
owing  chiefly  to  radiation,  as  beautifully  illustrated  by  Dr.  Wells. 

(nn.)  Why,  in  hot  weather,  is  a  house  cooler  if  kept  dark,  than  if 
light  and  air  are  freely  admitted  ? — Because  the  radiant  heat,  flow- 
ing, not  from  the  sun  only,  but  from  all  external  objects,  some  of 
which  are  often  much  heated,  is  also  excluded. 

(oo.)  Why  is  white  a  good  color  for  the  roof  of  an  ice  house,  and 
black  a  bad  color  for  any  roof? — Because  the  former  reflects,  and 
the  latter  absorbs  the  heat  rapidly. 

EXPERIMENTAL  ILLUSTRATIONS. 

i.  Inequality  of  conducting  power. — Dr.  Hare,  from  I  to  11,  ex- 
cept 3,  4,  and  8. 


"  Let  there  be  four  rods,  severally  of  metal, 
wood,  glass,  whale  bone,  each  cemented  at  one 
end  to  a  ball  of  sealing  wax.  Let  each  rod,  at 
the  end  which  is  not  cemented  to  the  wax,  be 
successively  exposed  to  the  flame  excited  by  a 
blow  pipe.  It  will  be  found,  that  the  metal  be- 
comes quickly  heated  throughout,  so  as  to  fall 
off"  from  the  wax — but,  that  the  wood,  or  whale- 
bone, may  be  destroyed,  and  the  glass  bent,  by 
the  ignition,  very  near  to  the  wax,  without  melt- 
ing it,  so  as  to  liberate  them." 


*  The  colored  surfaces  receiving  the  rays,  and  the  waxed  side  being  downwards. 


HEAT  OR  CALORIC. 


2.   Glass  so  heated  by  the  friction  of  a  cord,  as  to  separate  into 
two  parts,  on  being  subjected  to  cold  water. 


"  Some  years  ago,  Mr.  Lukens  showed  me,  that  a  small  phial 
tube,  might  be  separated  into  two  parts,  if  subjected  to  cold  water, 
after  being  heated  by  the  friction  of  a  cord  made  to  circulate  about 
it  by  two  persons  alternately  pulling  in  opposite  directions.  I  was 
subsequently  enabled  to  employ  this  process,  in  dividing  large  ves- 
sels, of  four  or  five  inches  in  diameter,  and  likewise  to  render  it,  in 
every  case  more  easy,  and  certain,  by  means  of  a  piece  of  plank 
forked  like  a  boot  jack — as  represented  in  the  preceding  figure — 
and  also  having  a  kerf,  or  slit,  cut  by  a  saw,  parallel  to,  and  nearly 
equi-distant  from,  the  principal  surfaces  of  the  plank,  and  at  right 
angles  to  the  other  incisions." 

"  By  means  of  the  fork,  the  glass  is  easily  held  steady  by  the  hand 
of  one  operator.  By  means  of  the  kerf,  the  string,  while  circulating 
about  the  glass,  is  confined  to  the  part,  where  the  separation  is  de- 
sired. As  soon  as  the  cord  smokes,  the  glass  is  plunged  into  water, 
or  if  too  large  to  be  easily  immersed,  the  water  must  be  thrown  upon 
it,  This  method  is  always  preferable  when  the  glass  vessel  is  so  open, 
that  on  being  immersed,  the  water  can  reach  the  inner  surface.  As 
plunging  is  the  most  effectual  method  of  employing  the  water,  in  the 
case  of  a  tube,  I  usually  close  the  end  which  is  to  be  sunk  in  the  wa- 
ter, so  as  to  restrict  the  cooling  to  the  outside." 

10 


iter, 


74  HEAT  OR  CALORIC, 

3.  METALS,  &tc. — Provide  as  many  equal 
cylinders  of  metals  as  may  be  desired ;  fix 
them  vertically  in  a  perforated  copper  or 
iron  plate,  their  lower  ends  resting  on  a 
similar  and  parallel  plate  connected  with  the 
upper  one  at  a  small  distance  by  metallic  posts. 
Place  upon  each  metallic  cylinder  a  thin 
slice  of  phosphorus,  and  set  the  apparatus 
upon  hot  sand  contained  in  an  iron  pan ;  the 
pieces  of  phosphorus  will  successively  take 
fire,  in  the  order  (caeteris  paribus)  correspon- 
ding with  the  conducting  power  of  the  metals. 

If  *™  b*  a  8lass  cy«?d«  7°°6  *e  others 
the  phosphorus  upon  that  will  not  take  fire.* 
4.  METALS  AND  WOOD. — A  solid  piece  of  metal  one  and  a  half 
inches  in  diameter,  and  eight  inches  long,  closely  wrapped  in  clean  writ- 
ing paper,  will  bear  to  be  immersed  in  the  flame  of  a  spirit  lamp,  for 
a  considerable  time,  without  scorching  the  paper ;  but  if  the  paper 
be  applied  to  a  piece  of  wood,  and  heated  in  a  similar  manner,  the 
paper  will  immediately  burn. — L.  u.  K. 

5.  Liquids  almost  destitute  of  conducting 

power. 

That  liquids  are  almost  devoid  of  power  to 
conduct  heat  is  proved  by  the  inflammation 
of  Ether,  over  the  bulb  of  an  air  ther- 
mometer, protected  only  by  a  thin  stratum 
of  water. 

"The  inflammation  of  ether,  upon  the 
surface  of  water,  as  represented  in  this  fig- 
ure, does  not  cause  any  movement  in  the  li- 
quid included  in  the  bore  of  the  thermom- 
eter at  L,  although  the  bulb  is  within  a  quar- 
ter of  an  inch  of  the  flame.  Yet  the  ther- 
mometer may  be  so  sensitive,  that  touching 
the  bulb,  while  under  water,  with  the  fin- 
gers, may  cause  a  very  perceptible  indica- 
tion of  increased  temperature." 

"  By  placing  the  sliding  index  I,  directly 
opposite  the  end  of  the  liquid  column  in 
the  stem  of  the  thermometer,  before  the 
ether  is  inflamed,  it  may  be  accurately  dis- 
covered whether  the  heat  of  the  flame  cau- 
ses any  movement  in  the  liquid." 

*  Sometimes  the  phosphorus  will  melt  in  the  air,  without  taking  fire,  but  on 
jarring  the  apparatus,  it  will  blaze  ;  a  thin  film  of  oxidized  phosphorus  apparently 
protects  the  phosphorus  below  from  combustion. 


HEAT  OR  CALORIC. 


75 


CIRCULATION    INDISPENSABLE,    TO    AN    EFFECTUAL    COMMUNICATION 
OF    HEAT    IN   LIQUIDS. 

6.  Different  effects  of  heat  on  the  upper  or  lower  strata  of  a  liquid. 


H 


B 


"A  glass  jar,  about  30  inches  in 
height,  is  supplied  with  as  much 
water  as  will  rise  in  it  within  a  few 
inches  of  the  brim.  By  means  of 
a  tube*  descending  to  the  bottom, 
a  small  quantity  of  blue  coloring 
matter  is  introduced  below  the  col- 
orless water,  so  as  to  form  a  stratum 
as  represented  at  A,  in  the  engrav- 
ing. A  stratum,  differently  colored, 
is  formed  in  the  upper  part  of  the 
vessel,  as  represented  at  B.  A  tin 
cap,  supporting  a  hollow  tin  cylin- 
der, closed  at  bottom,  and  about  an 
inch  less  in  diameter  than  the  jar, 
is  next  placed  as  it  is  seen  in  the 
drawing,  so  that  the  cylinder  may 
be  concentric  with  the  jar,  and  de- 
scend about  3  or  4  inches  into  the 
water." 

"  The  apparatus  being  thus  pre- 
pared, if  an  iron  heater,  H,  while 
red  hot,  be  placed  within  the  tin 
cylinder,  the  colored  water,  about 
it,  soon  boils ;  but  the  heat  pene- 
trates only  a  very  small  distance  be- 
low the  tin  cylinder,  so  that  the  col- 
orless water,  and  the  colored  stra- 
tum, at  the  bottom  of  the  vessel, 
remain  undisturbed,  and  do  not 
But  if  the  ring,  R,  be  placed,  while  red  hot,  upon  the  iron 


mingle. 


R 


stand  which  surrounds  the  jar  at  S  S,  the  portion  of  the  liquid,  color- 
ed blue,  being  opposite  to  the  ring,  will  rise  until  it  encounters  the 
warmer,  and  of  course  lighter  particles,  which  have  been  in  contact 
with  the  tin  cylinder.  Here  its  progress  upwards  is  arrested  ;  and  in 


*  e.  g.  A  dropping  tube. 


76  HEAT  OR  CALORIC 

consequence  of  the  diversity  of  the  colors,  a  well  defined  line  of 
separation  is  soon  visible.*' 

"  The  phenomena  of  this  interesting  experiment  may  be  thus  ex- 
plained." 

"  If  the  upper  portion  of  a  vessel,  containing  a  fluid,  be  heated  ex- 
clusively, the  neighboring  particles  of  the  fluid,  being  rendered  light- 
er, by  expansion,  are  more  indisposed,  than  before,  to  descend  from 
their  position.  But,  if  the  particles,  forming  the  inferior  strata  of  the 
fluid  in  the  same  vessel,  be  rendered  warmer  than  those  above  them, 
their  consequent  expansion  and  diminution  of  specific  gravity,  causes 
them  to  give  place  to  particles  above  them,  which,  not  being  as 
warm,  are  heavier.  Hence,  heat  must  be  applied  principally  to  the 
lower  part  of  a  vessel,  in  order  to  occasion  a  uniform  rise  of  tempe- 
rature in  a  contained  fluid." 

"  This  statement  is  equally  true,  whether  the  fluid  be  aeriform,  or  a 
liquid,  excepting  that  in  the  case  of  aeriform  fluids,  the  influence  of 
pressure  on  their  elasticity,  may  sometimes  co-operate  with,  and  at 
others  oppose,  the  influence  of  temperature." 

7.  Process  by  which  caloric  is  distributed  in  a  liquid  before  it  boils. 

"On  the  first  application  of 
heat  to  the  bottom  of  a  vessel  con- 
taining cold  water,  the  particles 
in  contact  with  the  bottom  are 
heated  and  expanded,  and  con- 
sequently become  lighter  in  pro- 
portion to  their  bulk,  than  those 
above  them.  They  rise  therefore, 
giving  an  opportunity  to  other 
particles  to  be  heated,  and  to  rise 
in  their  turn.  The  particles 
which  were  first  heated,  are  soon, 
comparatively,  colder  than  those 
by  which  they  were  displaced, 
and,  descending  to  their  primi- 
tive situation,  are  again  made  to 
rise,  by  additional  heat,  and  en- 
largement of  their  bulk.  Thus 
the  temperatures  reversing  the 
situations,  and  the  situations  the 


*  "I  used  to  perform  this  experiment  with  an  inclined  tube,  as  suggested  in 
Henry's  Chemistry.  The  modification  here  given,  is  so  far  a  contrivance  of  my 
own,  as  relates  to  the  use  of  the  heater,  tin  cap,  and  iron  ring ;  and  the  employment 
of  two  colors  instead  of  one.  On  account  of  the  liability  of  the  glass  to  crack,  I 
found  the  old  method  very  precarious,  when  a  tube  was  used  large  enough  to  show 
the  phenomena  advantageously." 


HEAT  OR  CALORIC.  77 

temperatures,  an  incessant  circulation  is  supported,  so  long  as  any 
one  portion  of  the  liquid  is  cooler  than  another  ;  or  in  other  words, 
till  the  water  boils ;  previously  to  which,  every  particle  must  have 
combined  with  as  much  caloric,  as  it  can  receive,  without  being  con- 
verted into  steam." 

"  The  manner  in  which  caloric  is  distributed  throughout  liquids  by 
circulation,  as  above  described,  is  illustrated  advantageously  by  an  ex- 
periment contrived  by  Rumford,  who  first  gave  to  the  process,  the  at- 
tention which  it  deserves." 

"Into  a  glass  nearly  full  of  water,  as  represented  by  the  foregoing 
figure,  some  small  pieces  of  amber  are  introduced,  which  are  in  spe- 
cific gravity  so  nearly  equal  to  water,  as  to  be  little  influenced  by  grav- 
itation." 

"  The  lowermost  part  of  the  vessel  being  subjected  to  heat,  while 
thus  prepared,  the  pieces  of  amber  are  seen  rising  vertically  in  its 
axis,  and  after  they  reach  the  surface  of  the  liquid,  moving  towards 
the  sides,  where  the  vessel  is  colder  from  the  influence  of  the  exter- 
nal air.  Having  reached  the  sides  of  the  vessel,  they  sink  to  the 
bottom,  whence  they  are  again  made  to  rise  as  before.  While  one 
set  of  the  fragments  of  amber,  is  at  the  bottom  of  the  liquid,  some 
are  at  the  top,  and  others  at  intermediate  situations  ;  thus  demonstra- 
ting the  movements,  by  which  an  equalization  of  temperature  is  ac- 
complished in  liquids." 

"  When  the  boiling  point  is  almost  attained,  the  particles  being 
nearly  of  one  temperature,  the  circulation  is  retarded.  Under  these 
circumstances,  the  portions  of  the  liquid  which  are  in  contact  with 
the  heated  surface  of  the  boiler,  are  converted  into  steam,  before 
they  can  be  succeeded  by  others ;  but  the  steam  thus  produced,  can- 
not rise  far  before  it  is  condensed.  Hence  the  vibration  and  singing, 
which  is  at  this  time  observed." 

8.  Provide  a  glass  tube  twelve  or  fifteen  inches  long  and  from 
two  to  two  and  a  half  wide,  closed  at  one  end,  and  that  end  thin,  so 
as  to  bear  heat ;  nearly  fill  the  tube  with  alcohol,  and  then  with  a 
dropping  tube,  convey  to  the  bottom  some  alcohol,  colored  by  turmeric 
or  cochineal  and  rendered  a  little  heavier  by  water ;  if  dexterously 
done,  there  will  be  a  well  defined  line  of  separation ;  then  apply  heat 
at  the  bottom,  and  the  color  will  be  rapidly  diffused. 

Now  repeat  the  experiment,  only  place  the  colored  alcohol*  on  the 
surface ;  the  color  on  the  top  will  be  scarcely  disturbed  till  the  fluid 
begins  to  boil. 

*  Jt  is  hardly  necessary  to  say,  that  no  water  should  be  added  to  it. 


78 


HEAT  OR  CALORIC. 


9.  Model  for  illustrating  the  operation  of  concave  mirrors. 

"The  object  of 
the  model  repre- 
Asented  by  this  dia- 
gram, is  to  explain 
the  mode  in  which 
two  mirrors  oper- 
ate, in  collecting 
the  rays  of  radiant 
heat  emitted  from 
one  focus,  and  in 
concentrating  them  in  another." 

"  The  caloric  emitted  by  a  heated  body  in  the  focus  of  the  mirror 
A,  would  pass  off  in  radii  or  rays  lessening  their  intensity,  as  the 
space  into  which  they  pass  enlarges;  or,  in  other  words,  as  the 
squares  of  the  distances.  But  those  rays  which  are  arrested  by  the 
mirror,  are  reflected  from  it  in  directions  parallel  to  its  axis.*  Be- 
ing thus  corrected,  of  their  divergency,  they  may  be  received,  with- 
out any  other  loss,  than  such  as  arises  from  mechanical  imperfections, 
by  the  other  mirror ;  which  should  be  so  placed,  that  the  axes  of  the 
two  mirrors  may  be  coincident ;  or,  in  other  words,  so  that  a  line 
drawn  through  their  centres,  from  A  to  B,  may  at- the  same  time  pass 
through  their  foci,  represented  by  the  little  balls  supported  by  the 
wires,  WW." 

"  The  second  mirror,  B,  reflects  to  its  focus,  the  rays  which  reach 
it  from  the  first ;  for  it  is  the  property  of  a  mirror,  duly  concave,  to 
render  parallel  the  divergent  rays  received  from  its  focus, — and  to 
cause  the  parallel  rays  which  it  intercepts,  to  become  convergent,  so 
as  to  meet  in  its  focus." 

"  The  strings,  in  the  model,  are  intended  to  represent  the  paths, 
in  which  the  rays  move,  whether  divergent,  parallel,  or  convergent." 

10.  Phosphorus^  kindled  at  the  distance  of  twenty,  or  even  at  six- 
ty feet,  by  an  incandescent  iron  ball. — Dr.  Hare. 

"  The  annexed  figure  represents  the  mirrors,  which  I  employ  in 
the  ignition  of  phosphorus,  and  lighting  a  candle,  by  an  incandescent 
iron  ball  at  the  distance  of  about  twenty  feet." 

"  I  have  produced  this  result  at  sixty  feet,  and  it  might  be  always 
effected  at  that  distance,  were  it  not  for  the  difficulty  of  adjusting  the 
foci  with  sufficient  accuracy  and  expedition.  I  once  ascertained 
that  a  mercurial  thermometer,  when  at  the  distance  last  mentioned., 
was  raised  to  110  degrees  of  Fahrenheit." 


*  "  The  axis  of  a  mirror  is  in  a  line  drawn  from  its  centre  through  its  focus." 
t  Especially  if  enveloped  in  cotton,  which  is  a  bad  conductor. 


HEAT  OR  CALORIC. 


79 


80 


HEAT  OR  CALORIC. 


"  Some  cotton,  imbued  previously  with  phosphorus,  is  supported 
by  a  wire  over  a  candle  wick,  placed  as  nearly  as  possible,  in  the 
focus  of  one  of  the  mirrors.  A  lamp  being  similarly  situated  with 
respect  to  the  other  mirror ;  by  receiving  the  focal  image  of  the 
flame  on  any  small  screen,  it  will  be  seen  in  what  way  the  arrange- 
ment must  be  altered  to  cause  this  image  to  fall  upon  the  phos- 
phorus." 

"  The  screen  S,  placed  between  the  mirrors,  is  then  lowered  so 
as  to  intercept  the  rays.  The  iron  ball  being  rendered  white  hot,  is 
now  substituted  for  the  lamp,  and  the  screen  being  lifted,  the  phos- 
phorus takes  fire,  and  the  candle  is  lighted." 

"  Description  and  construction  of  the  mirrors. — The  mirrors  rep- 
resented by  the  figure,  are  sixteen  inches  in  diameter,  and  were 
turned  in  the  lathe,  the  cutting  tool  being  attached  to  one  end  of  an  iron 
bar  two  feet  long,  which  at  the  other  end  turned  upon  a  fixed  pivot." 

"  Of  course  the  focal  distance,  being  one  half  the  radius  of  con- 
cavity, is  one  foot." 

"  I  designed  these  mirrors,  and  proposed  to  have  them  made  out 
of  castings  ;  but  pursuant  to  the  advice  of  Dr.  Thomas  P.  Jones,  I 
resorted  to  sheet  brass,  which  was  rendered  the  more  competent  by 
strengthening  the  rims  with  rings  of  cast  brass,  about  three  fourths  of 
an  inch  thick  each  way.  For  the  idea  of  these  rings,  and  the  execu- 
tion of  the  mirrors,  I  am  indebted  to  Mr.  Jacob  Perkins." 

"  I  believe  there  are  none  superior,  as  the  face  is  reflected  by  them 
much  magnified,  but  without  the  slightest  distortion." 

"  For  die  rationale  of  the  operation  of  the  mirrors,  I  refer  to  the 
preceding  article." 

11.  Diversity  of  radiating  power  in  metals,  wood,  charcoal,  glasst 
pottery,  fyc. 


E 


HEAT  OR  CALORIC.  81 

u  At  M,  in  the  preceding  figure,  a  parabolic  mirror  is  represented. 
At  B,  a  square  glass  bottle,  one  side  of  which  is  covered  with  tinfoil, 
and  another  so  smoked  by  means  of  a  lamp,  as  to  be  covered  with 
carbon.  Between  the  bottle  and  mirror,  and  in  the  focus  of  the  lat- 
ter, there  is  a  bulb  of  a  differential  thermometer,  protected  from  re- 
ceiving any  rays  directly  from  the  bottle,  by  a  small  metallic  disk. 
The  bottle  being  filled  with  boiling  water,  it  will  be  found  that  the 
temperature  in  the  focus,  as  indicated  by  the  thermometer,  is  greatest 
when  the  blackened  surface  is  opposite  to  the  mirror  ;  and  least,  when 
the  tinfoil  is  so  situated ;  the  effect  of  the  naked  glass  being  greater 
than  the  one,  and  less  than  the  other." 

"  When  a  polished  brass  andiron  is  exposed  from  morning  till  night 
to  a  fire,  so  near  as  that  the  hand,  placed  on  it,  is  scorched  intolera- 
bly in  a  few  seconds,  it  does  not  grow  hot."* 

"  Fire  places  should  be  constructed  of  a  form  and  materials  to  fa- 
vor radiation  :  flues,  of  materials  to  favor  the  conducting  process." — 

12.  A  cork  thrust  into  a  candlestick  ;  some  black  wool  pushed  by 
a  knife  into  a  slit  in  the  cork  ;  some  thin  slices  of  phosphorus  or  sul- 
phuret  of  phosphorus,  laid  upon  the  wool  or  wrapped  in  it,  the  focus 
being  previously  ascertained  by  the  light  of  a  candle,  will  hardly  ever 
fail  of  success,!  an  ignited  iron  ball  or  a  few  live  coals  being  placed 
in  the  other  focus.     A  screen  of  glass  or  metal  may  be  held  between 
the  mirrors  till  we  are  ready  for  the  result. 

13.  Fulminating  mercury,  or  silver,  or  gunpowder,  maybe  sprink- 
led on  the  wool  or  on  charcoal,  but  they  will  by  their  explosion  soil 
the  mirror :  the  effect  is  otherwise  agreeable. 

14.  Boiling  water  being  in  one  focus  and  a  delicate  air,  or  differen- 
tial thermometer  in  the  other,  there  is  an  evident  movement  of  the  fluid, 
and  the  glass  screen  being  interposed,  arrests  and  soon  reverses  the 
effect. 

15.  A  bright  metallic  mirror,  held  before  a  common  fire,  remains 
cold,  but,  if  blackened  by  candle  smoke  or  India  ink,  it  becomes  hot. 

16.  Provide  two  bright  tin  flasks  or  polished  metallic  tea  pots ;  black- 
en one  with  candle  or  lamp  smoke,  then  pour  boiling  hot  water  from  a 
tea  kettle  into  both ;  examine  the  temperature,  at  intervals  of  five 
minutes,  and  it  will  be  found  that  for  more  than  an  hour,  the  bright 
vessel  will  remain  decidedly  the  hottest,  and  sensibly  so  for  several 
hours.  J 

17.  Fill  them  with  cold  water  and  place  them  before  a  bright  fire  ; 
the  blackened  vessel  will  become  hot,  and  the  other  will  remain  cold. 


*  Except  that  a  little  heat  passes  by  slow  communication  along  the  iron  bar. 

t  A  mouse  trap  without  the  bottom,  supported  by  the  ring  of  a  retort  stand,  makes  a 
good  fire  grate,  and  a  sheet  of  copper,  zinc,  or  iron,  will  protect  the  table  from  the 
falling  coals.  t  See  the  statement  of  experiments,  page  71. 

11 


82  HEAT  OR  CALORIC. 

With  a  mask  coated  with  tin  foil,  our  faces  may  safely  encounter  the; 
blaze  of  a  glass  house  furnace. — lire's  Die.  277. 

18.  Hot  water  cools  faster  in  a  glass,  than  in  a  polished  metallic- 
vessel. 

19.  "Radiation  of  cold. — -A  thermometer,  placed  in  the  focus  of 
a  mirror,  indicates  a  decline  of  temperature,  in  consequence  of  a  mas? 
of  ice  or  snow  being  placed  before  it,  in  the  situation  occupied  by  the 
bottle,  in  the  preceding  figure.     This  change  of  temperature  has 
been  ascribed  to  the  radiation  of  cold,  and  has  been  considered  a? 
demonstrating  the  materiality  of  that  principle.     For,  since  the  trans- 
fer of  heat,  by  radiation,  has  been  adduced  as  a  proof  of  the   exis- 
tence of  a  material  cause  of  heat ;  it  is  alleged  that  the  transmission 
of  cold,  by  the  same  process,  ought  to  be  admitted  in  evidence,  of  a 
material  cause  of  cold."* 

But,  it  is  necessary  to  suppose  only  that  the  heat  flows  from  the 
thermometer,  which  is  relatively  the  hotter  body,  to  the  ice,  which  is 
constantly  absorbing  the  radiant  heat  of  the  room  and  that  of  the 
thermometer  more  than  of  any  other  body,  because  the  heat  is  there 
concentrated  by  the  mirrors,  and  thence  flows  in  greater  quantities 
than  is  true  of  any  other  place. f 

III.  CONGELATION  AND  LIQUEFACTION. 

(a.)  Dr.  Black  first  proved  that  fluidity  depends  on  a  peculiar  com- 
bination or  operation  of  heat  or  caloric. 

(b.)  The  sensible  heat  of  both  melting  ice  and  freezing  water  is 
at  all  times  and  places  32°  of  jFoAr.J — H. 

The  water,  when  first  formed  by  melting,  is  at  32°,  and  the  heat 
absorbed  during  liquefaction  has  merely  melted  the  ice,  and  has  not 
raised  its  temperature.  If  ice  is  colder  than  32%  it  cannot  melt  till 
it  attains  that  temperature,  and  the  sensible  heat  will  neither  rise  nor 
fall  during  the  process  of  melting. 

(c.)  The  quantity  absorbed  is  140° — A  pound  of  snow  at  32°  and 
a  pound  of  water  at  172°,  if  quickly  mingled,  will  give  the  tempera- 
ture of  32°,  therefore  140°  have  been  absorbed  to  melt  the  ice,  and 
are  not  discoverable  by  the  senses  or  by  the  thermometer.^ 


*  Dr.  Hare. 

1  Ice  at  32°,.  is  a  radiant  point  of  heat  in  an  atmosphere  of  0,  and  a  freezing  mix- 
ture, e.  g.  salt  and  snow  producing  a  cold  of  0,  would  be,  relatively,  a  warm  point  in 
a  medium  of  40°  below  0. 

t  The  freezing  and  melting  points  of  all  bodies  are  the  same  lor  each  particular 
body,  but  no  two  coincide,  unless  by  chance  ;  c.  g.  solid  mercury  melts  at — 39 
solid  water  or  ice  at-j-32°.  Most  bodies,  as  the  metals,  melt  without  becoming  pre- 
viously soft,  but  others  which  are  bad  conductors,  become  soft  first,  as  butter  and 
sulphur. 

§  Several  other  experiments  of  Dr.  Black,  go  to  prove  the  same  result,  namely 
thai  while  ice  is  melting,  a  quantity  of  heat  enters  into  it,  without  raising  its  tempe- 
rature, which  would  raise  that  of  water  140°. 


HEAT  OR  CALORIC.  83 

(d.)  Freezing  water  gives  out  140°  of  heat. — This  warms  the  in- 
cumbent air,  which  rises  and  affects  a  delicate  thermometer,  suspend- 
ed above  the  freezing  fluid.  Freezing  is  therefore  a  warming  process, 
and  sensibly  mitigates  the  severity  of  winter  ;  the  140°  being  near- 
}y  the  whole  difference  between  the  extreme  climates  of  the  globe, 
and  being  given  out  from  the  extensive  surface  of  the  freezing  waters 
and  plants,  which  are  imbued  with  moisture,  it  greatly  mitigates  the 
atmospheric  cold. 

(e.)  Melting  ice,  especially  if  suspended ',  is  attended  by  a  descend- 
ing current  of  cold  air,  which  is  perceptible  even  to  the  hand,  and 
still  more,  by  means  of  a  delicate  thermometer.  Liquefaction  is 
therefore  a  cooling  process,  as  is  perceived  also  from  the  chilly  air 
produced  by  melting  snow  in  a  bright  day. 

(/*.)  Water  cooled  beloiu  32°,  if  agitated,  congeals  into  a  spongy 
mass  of  ice;  the  evolved  latent  heat  raises  the  temperature  to  32°,  and, 
a  part  of  the  ice  slowly  melts  again. — Water  may  be  cooled  20°  or 
more  below  the  freezing  point,  or  32°  of  Fahr.  This  is  best  done  in 
a  tall  vessel,  with  a  narrow  mouth,  and  with  a  film  of  oil  over  the 
surface  of  the  water  ;  it  happens  often  accidentally  in  domestic  ves- 
sels, in  cold  weather.  Water  thus  cooled,  immediately  commences 
freezing,  if  a  particle  of  ice  or  even  a  crystal  that  is  floating  in  the  air, 
happens  to  enter  the  fluid. 

(g.)  All  solids  absorb  heat  when  becoming  fluid  and  retain  it  while 
in  that  state. — The  quantity  of  heat  is  different  in  different  cases, 
and  is  to  be  learned  only  by  experiment. 

Sulphur  absorbs  143°.68  of  Fahr.  spermaceti  145°,  lead  162°, 
beeswax  175°,  zinc  493°,  tin  500°,  bismuth  550°.— Black,  Henry. 

(h.)  The  particular  quantity  of  heat  which  renders  a  substance 
fluid,  is  called  its  latent  heat,  or  caloric  of  fluidity. — The  word  latent 
was  used  by  Dr.  Black,  merely  to  denote  the  condition  in  which  the 
heat  exists  ;  latet,  it  lies  concealed. 

It  is  not  a  different  kind  of  power,  but  merely  heat  in  an  insensible 
condition  and  manifesting  its  character  by  a  peculiar  effect,  that  of 
producing  fluidity. 

(i.)  Freezing  mixtures,  depend  upon  these  principles. — One  ingre- 
dient in  them,  is  always  a  solid,  and  in  producing  the  effect  of  gene- 
rating cold,  this  solid  always  melts  or  liquefies,  and  thus  absorbs  heat. 
When  both  substances  are  solid,  as  snow  and  muriate  of  lime,  or 
snow  and  caustic  potash,  or  snow  and  common  salt,  the  effect  is  of 
course  greater.  • 

(j.)  Heat  is  evolved  during  the  conversion  of  fluids  into  solids. — 
This  is  well  illustrated  by  the  slacking  of  lime  and  the  mixing  of  wa- 
ter with  burned  plaister  of  Paris,  in  both  of  which  cases,  the  water 
becomes  solid  and  heat  is  evolved. 


84  HEAT  OU  CALORIC. 

A  saturated  solution  of  sulphate  of  potash  precipitated  hy  alcohol 
evolves  considerable  heat,  when  the  salt  congeals. — Henry. 

!/£.)  Were  there  no  absolution  of  heat  to  become  latent  during  the 
ting  of  ice,  countries  covered  with  snow  might  be  instantaneously 
devastated. — The  torrents  are  even  now,  very  destructive  ;  then,  they 
would  be  ruinous.  Snow  and  ice  would  instantly  melt,  as  soon  as 
the  temperature  rose  above  32°,  but  as  the  absorption  of  140°  of 
heat  is  indispensable,  the  process  is  necessarily  a  slow  one. 

(/.)  The  heat  absorbed  in  liquefaction,  is  given  out  again  in 
freezing. — Thus  one  cause  tends  to  correct  the  effect  of  the  other, 
and  both  causes  conspire  to  regulate  the  temperature  ;  for  thawing  is 
a  cooling,  and  freezing  is  a  warming  process. 

IV.  VAPORIZATION  AND  GASIFICATION   OR  THE   FORMATION  OF 

AERIFORM    BODIES. 

Introductory  Remarks. 

Weight  and  pressure  of  the  atmosphere. — This  subject  belongs  to 
mechanical  philosophy,*  but  it  is  impossible  to  make  any  progress  in 
investigating  the  nature  of  aerial  agents,  without  taking  into  view  the 
pressure  of  the  atmosphere.  Its  existence  is  fully  demonstrated,  by 
the  rise  of  water  in  a  pump,  and  by  the  stationary  condition  of  the 
column  of  mercury  in  a  barometer  tube,  as  wrell  as  by  many  com- 
mon occurrences. f  The  pressure,  in  any  given  place,  varies  at  dif- 
ferent times,  but  the  mediuni  is  about  fifteen  pounds  on  the  square 
inch,  corresponding  to  a  column  of  thirty  inches  in  the  barometer ;  to 
about  thirty  three  feet  of  water,  and  to  columns  of  other  fluids  varying 
in  height  according  to  their  specific  gravity. 

Taking  the  doctrine  of  atmospheric  pressure  for  granted,  we  pro- 
ceed to  aeriform  bodies. 

(a)  Jin  atriform  body  is  one  having  the  mechanical  properties  of  air  ;  J 
a  vapor  is  a  transient  aeriform  body,  condensible  by  cold,  or  pressure,  or 
both  united  ;  a  gas  is  supposed  to  be  permanently  aeriform  under  eve- 
ry degree  of  pressure  and  cold. — Some  latitude  is  allowed  in  the  use 
of  these  terms,  and  a  few  bodies  continue  to  be  called  gases,  which 
have  been  condensed ;  e.  g.  ammonia,  euchlorine,  sulphurous  acid. 


*  Consult  EnfielcPs  Philosophy,  and  any  other  treatise  on  Natural  Philosophy. — 
This  subject  and  that  of  statical  pressure  in  general,  is  ably  illustrated  by  Dr.  Hare, 
in  his  Compendium,  p.  25. 

t  It  is  now  said  that  flies  and  other  insects  walk  on  the  ceiling  of  a  room  with 
iheir  backs  downwards,  in  consequence  of  the  peculiar  webbed  structure  of  their 
feet,  which  enables  them  to  press  the  wall  so  closely,  that  little  or  no  air  intervenes, 
and  thus  the  pressure  of  the  atmosphere  keeps  them  in  their  places. — L,.  u.  K. 

$  Atmospheric  air  has,  by  pressure,  been  reduced  to  Tl^  part  of  its  volume,  with- 
out losing  its  clastic  form. 


HEAT  OR  CALORIC.  85 

sulphuretted  hydrogen,  carbonic  acid,  nitrous  oxide,  cyanogen,  muri- 
atic acid,  and  chlorine.* 

Strictly,  the  distinction  between  vapors  and  gases,  although  conven- 
ient in  description,  is  unimportant.  A  vapor  is  derived  from  a  body 
whose  vaporific  point  is  within  our  reach  ;  but  that  of  a  true  gas,  is 
lower  than  our  means  will  enable  us  to  go. 

(b.)  Caloric  converts  both^  solids  and  fluids  into  gases,  and  vapors. 
— Camphor,  benzoic  acid,  and  carbonate  of  ammonia,  are  easily 
converted  into  vapor,  by  being  thrown  upon  a  warm  iron  ;  a  bell 
glass  may  be  placed  over  them  to  catch  the  vapor.  Some  solids  are 
volatilized  without  previous  fusion — sal  ammoniac  and  arsenic  are  of 
this  number. 

(C.)    WlTH  EQUAL  PRESSURE  AND  PURITY,    EVERY  LIQUID  HAS  A 

FIXED  BOILING  OR  VAPORIFIC  POINT  ;  c.  g.  water,  the  barometer  be- 
ing at  30  inch,  boils  at  212°  ;  ether,  at  96°  or  98°  ;{  alcohol,  173° 
to  176°.§ 

Water  in  a  glass  vessel  boils  at  214°  or  216° — in  a  metallic  ves- 
sel, at  212°.  The  boiling  point  in  most  liquids,  is  lowered  several 
degrees  by  putting  in  chips  of  wood,  coils  of  wire,  metallic  filings, 
pounded  glass,  &c. — The  bubbles  of  steam  are  thus  broken,  and  the 
heat  escapes  more  rapidly.  Dr.  Bostock  thus  reduced  the  boiling 
point  of  ether,  50°,  and  that  of  alcohol,  30°. || 

(d.)  The  steam  or  vapor,  is  of  the  same  temperature  with  the  boil- 
ing liquid. 

(E.)  PHENOMENA  OF  EBULLITION — explained  by  the  instance  of 
water.  As  the  water  is  warming  from  the  common  temperature,  it 
is  first  thrown  into  currents  by  the  change  of  specific  gravity,  and 
when  it  arrives  at  2 12°, IT  elastic  vapor  then  forms  at  the  bottom  of  the 
fluid,  and  from  its  levity  ascends,  is  condensed  and  disappears ;  it  is 
followed  by  other  bubbles,  and  when  the  water  is  thus  all  heated  to  the 
boiling  point,  the  vapor  passes  through  uncondensed,  and  is  dissipated 
at  the  top.  The  water  remains  at  212°  till  the  last  drop  is  exhaled. 

The  old  theories  of  palpable  fire,  or  matter  of  caloric,  of  air  bub- 
bles passing  through  the  water,  and  thus  causing  its  agitation,  &c. 
are  untenable,  and  unworthy  of  discussion.  Water,  in  the  aeriform 

*  See  Mr.  Faraday's  experiments  in  Philos.  Transac.  part  II.  for  1822,  and  Am. 
Jour.  Vol.  7  pa.  352. 

t  Dr.  Black  laid  the  foundation  of  the  philosophy  of  vapors  and  gases,  or  in  other 
words,  of  aeriform  bodies,  by  his  discoveries  respecting  latent  heat,  and  by  proving 
the  distinct  existence  of  an  auriform  body,  different  from  common  air,  namely,  carbo- 
nic acid  gas,  called  by  him,  fixed  air.  The  period  of  this  discovery  was  1757. 

t  Dr.  tire  says  100°. 

§  For  exceptions,  See  Henry,  10th  Lond.  Ed.  Vol.  I.  pa.  114 ;  Ann.  Philos.  new 
series,  IX.  296.  Ann.  de  Chim.  et  de  Phys.  torn,  VII.  pa.  307;  and  Jour.  Science, 
Vol  V.  pa.  361.  ||  Ann  Phil.  N.  S.  Vol.  IX. 

IT  And  also,  when  the  vapor  has  acquired  elastic  power  sufficient  to  lift  both  the 
atmosphere  and  the  superincumbent  fluid. 


36  HEAT  OR  CALOKIC. 

4 

state,  or  steam,  is  the  true  cause  of  the  mechanical  movements  in  liu-: 
boiling  fluid,  and  the  cloud  which  we  see  in  the  air  near  the  surface 
is  the  vapor  condensed  into  minute  drops  resembling  a  fog  or  mist. 
The  singing  arises  from  the  escape  of  innumerable  air  bubbles,  and 
the  crackling  noise,  that  precedes  boiling,  and  ceases  when  it  begins, 
is  owing  to  the  formation  of  elastic  vapor,  and  its  immediate  conden- 
sation by  the  colder  fluid  above. 

(/.)  Perfectly  formed  vapor  is  invisible. — If  water  or  other  fluid 
be  boiled  in  a  glass  flask,  the  space  above  the  water,  appears  as  if 
the  vessel  were  empty,  and  the  cloud  at  the  mouth  consisting  of  con- 
densed steam,  in  the  form  of  mist,  would  not  be  seen,  if  the  air 
were  of  the  temperature,  212°. 

Ether,  in  thin  glass  vessels,  is  easily  vaporized  by  applying  boiling 
water,  and  condensed  again  by  cold  water. 

(G.)  The  latent  heatof  steam  is  about  950°  orfromthatto  1000°. 
— Dr.  Ure  adopts  the  latter  number,  which  is  probably  correct. 
This  is  proved,  by  distilling  one  gallon  of  water,  and  condensing  the 
vapor  in  a  worm  immersed  in  ten  gallons  of  the  same  fluid,  each  of 
which  will  receive  nearly  100°  of  heat,  and  this  multiplied  by  10, 
gives  the  above  result  very  nearly.*  Or  one  gallon  of  water  in  steam, 
will  heat  six  gallons  from  50°  to  212° ;  212^-50x6  =  972=:  latent 
heat  of  steam  very  nearly. 

Hence,  steam  is  an  excellent  vehicle  of  heat,  and  is  very  useful  in 
cookery,  in  heating  manufactories,  drying  gunpowder,  and  chemical 
precipitates,  in  heating  baths,  dye  vats,  and  apartments  for  invalids  5 
in  making  pharmaceutical  extracts,  and  in  many  other  cases.  Large 
vessels  of  wood  are  employed  with  great  economy  because  they  can 
be  heated  by  steam. 

(H.)  PRINCIPLE  OF  DISTILLATION. 

Caloric,  combining  ivith  the  more  volatile  part  of  a  fluid,  raises  it 
in  vayor;  it  is  again  condensed  by  the  cold  water  of  the  refrigeratory, 
which  thus  becomes  rapidly  hot,  and  must  be  often  changed ;  this  is 
usually  done  by  a  stream  of  cold  water  conveyed  into  the  condenser  ; 
on  one  side,  hot  water  runs  out,  and  on  another,  cold  water  runs  in.f 

A  retort  and  receiver  is  the  simplest  distilling  apparatus ;  the  fluid 
in  the  retort  is  made  to  boil,  and  the  vapor  is  condensed  in  the  re- 
ceiver, which  is  kept  cold  for  that  purpose.  Sublimation  is  the  same 
thing  in  principle,  as  distillation,  but  the  vapor  is  condensed  in  the 
solid  form  ;  this  is  seen,  in  the  case  of  camphor,  sulphur,  benzoic 
acid,  corrosive  sublimate,  calomel,  arsenic,  &c. 

*  Due  allowance  being  made  for  the  sensible  heat,  and  for  waste.  Henry,  10th 
Lond.  Ed.  Vol.  I.  p.  127. 

t  Col.  Wm.  Moseley  of  New  Haven,  ingeniously  avails  himself  of  the  cold  water 
at  the  bottom  and  of  the  hot  water  at  the  top  of  the  condensing  tub,  to  supply  baths 
conveniently  and  economically. 


HEAT  OR  CALORIC.  87 

Distillation  in  vacuo,  although  it  is  attended  by  no  economy  of 
heat,  is  a  good  mode  of  conducting  the  process,  where  the  product 
would  be  injured  by  a  high  temperature. 

Vinegar  as  commonly  distilled,  has  often  an  empyreumatic  taste, 
but  if  distilled  in  vacuo,  it  requires  only  130°  of  heat,  and  the  pro- 
duct is  pellucid  and  fine. — L.  u.  K. 

In  these  cases,  the  vacuum  is  obtained  either  by  driving  out  the 
air  by  the  vapor,  and  then  closing  the  aperture  of  the  receiving  ves- 
sel, or,  by  applying  a  syringe  or  air  pump  to  the  receiver,  cold  being 
also  of  course  in  all  cases  applied  to  the  receiver.* 

(i.)  The  specific  heat  of  the  vapors  of  different  fluids  is  different, 
and  can  be  ascertained  by  experiment  only. 

Table  of  latent  heat  of  vapors.^ 

Despretz,  Ann.  de 

Ure's  Die.  17.     Chim.  &c.  xxiv.  329. 
Vapor  of  Water,  at  212°  1000.  955.8 


Alcohol,  sp.  gr.  0.825,  457.    (sp.  gr.  .793, 

Sul.  ether,  boiling  point  104°,     312.9  (  "    "   .715, 
Spt.  turpentine,    "  about  310°,  183.8  ("    "   .872, 


373.86 
163.44 
„  138.24 

Petroleum,  183.8 

Nitric  acid,  (sp.  gr.  1 .494-— boiled  at  165°,)  550. 

Liquid  ammonia,  (sp.  gr.  0.978,)  865.09 

Vinegar,  (sp.  gr.  1.007,)  905. 

The  force  of  vapor  at  the  boiling  point  is  the  same  in  all  fluids ; 
it  is  equal  to  30  inches  of  mercury,  and  in  all  fluids,  is  the  same  for 


*  In  consequence  of  a  tax  laid  by  the  English  parliament  on  the  Scotch  stills,  by 
wffich  they  were  to  pay  thirty  shillings  a  year  on  every  gallon  of  the  capacity  of 
their  stills,  it  became  their  interest  to  make  them  work  as  fast  as  possible,  and  they 
made  such  improvements  in  the  construction  of  their  stills,  that,  although  the  tax 
was  augmented  by  degrees  from  thirty  shillings  a  year  on  a  gallon,  to  fifty  four 
pounds,  they  still  continued  to  carry  on  the  business  with  advantage.     The  improve- 
ments consisted  chiefly  iu  making  the  still  very  broad  and  very  flat,  so  that  only  a  small 
depth  of  wash  could  be  In  it  at  once,  leaving  a  very  large  orifice  for  the  escape  of  the 
vapor,  having  an  internal  moving  apparatus  for  agitating  the  wash,  to  prevent  its 
burning,  and  another  in  the  upper  part  of  the  still  to  break  the  frothy  effervescence, 
when  it  would  be  in  danger  of  boiling  over.     The  fire  was  applied  to  a  very  large 
surface  ;  the  ebullition  was  very  rapid  and  general ;  no  pressure  was  opposed  to  the 
escape  of  the  vapor,  and  thus  they  arrived  at  such  astonishing  rapidity  in  the  distilla- 
tion, as  to  run  off  their  stills  of  forty  or  fifty  gallons  capacity,  three  times  in  an  hour, 
or  seventy  two  times  in  twenty  four  hours,  (see  report  on  the  Scotch  Distillery,  Phil. 
Mag.  Vol.  VI.  pa.  76,)  and  by  improvements  still  subsequent,  they  brought  the  pro- 
cess to  such  perfection,  that  a  still  of  the  capacity  of  forty  gallons  in  the  body,  and 
three  in  the  head,  charged  with  sixteen  gallons  of  wash,  could  be  worked  four  hun- 
dred and  eighty  times  in  twenty  four  hours,  viz.  seven  thousand  six  hundred  and 
eighty  gallons  of  wash  could  be  distilled,  and  as  the  wash  would  afford  eighteen  per 
cent  of  spirit,  it  follows,  that  one  thousand,  three  hundred  and  eighty  two  gallons 
could  be  distilled  from  a  still  of  this  capacity  in  twenty  four  hours,  the  still  could  be 
worked  off  therefore,  twenty  times  in  an  hour,  or  once  in  three  minute;?,  and  gave 
about  fifty  eight  gallons  an  hour,  or  near  a  gallon  in  a  minute. 

*  Quoted  from  Henry,  10th  London  edit.  Vol.  I.  p.  125. 


88  HEAT  OR  CALORIC. 

an  equal  number  of  degrees  above  and  below  ebullition,  but  fixed 
oils,  sulphuric  acid  and  mercury,  afford  no  readily  appreciable  vapor 
under  the  boiling  point. 

(j.)  By  being  converted  into  steam,  a  cubic  inch*  of  water  be- 
comes nearly  a  cubic  foot  or  1728  cubic  inches.  Dr.  Black  and  Mr, 
Watt  estimated  the  enlargement  at  nearly  1800  times.  According  to 
Gay  Lussac  it  is  1698  times.  Alcohol,  in  vapor,  under  the  common 
pressure,  occupies  659  times  the  volume  that  it  did  when  liquid,  and 
ether  443  times.  The  specific  gravity  of  steam  is  623,  air  being 
1000,  but  the  vapor  of  alcohol  is  half  as  heavy  again  as  air,  and  that 
of  ether  more  than  twice  and  a  half  as  heavy,  and  generally  with  a 
few  exceptions,  the  lower  the  boiling  point  of  a  fluid,  the  more  dense 
is  the  vapor  formed  from  it. 

(K.)  THE   PRESSURE  OF  THE  ATMOSPHERE,   AND  PRESSURE  IN 

GENERAL,  EXERTS   AN  IMPORTANT  INFLUENCE   ON  VAPORIZATION. 

As  already  observed,  no  correct  conclusions  respecting  aeriform 
bodies  can  be  formed,  without  taking  this  subject  into  view. 

(/.)  The  pressure  of  the  atmosphere  is  measured  by  the  column  of 
mercury  which  it  is  capable  of  sustaining. — A  glass  tube  not  less  than 
32  inches  long  nor  over  half  an  inch  in  diameter,  closed  at  one  end, 
being  filled  with  mercury,  and  having  its  mouth  first  closed  by  the 
finger,  and  then  inverted  and  opened  under  the  surface  of  mercury, 
exhibits  die  amount  of  atmospheric  pressure,  vibrating  on  both 
sides  of  29  or  30  inches,  which  is  about  the  medium  of  different  cli- 
mates, seasons  and  countries. f 

(m.)  At  the,  medium  pressure,  pure  water  boils  at  212°  ;  if  the 
pressure  be  diminished,  water  and  all  fluids  boil  at  a  lower  tempera- 
ture.— This  is  shewn  by  the  air  pump,  and  by  the  Torricellian 
vacuum.  J  Natural  variations  of  atmospheric  pressure  vary  the  boil- 
ing point  about  5°. 

(n.)  According  to  Dr.  Slack,  fluids  boil  in  vacuo  ivith  124°  less 
of  heat  than  under  the  pressure  of  the  atmosphere  ;  others  say  with 
145°  less,  if  estimated  in  the  Torricellian  vacuum.^ 

As  we  ascend,  it  requires  less  heat  to  make  water  boil ;  on  the 
top  of  Mount  Blanc,  it  boils  at  187°, ||  and  on  the  range  of  Pasco, 
Peru,  at  180°.1T  In  the  Rev.  Mr.  Wollaston's  thermometer,  each 


*  Weight  252  grains.  The  specific  gravity  of  steam  at  212°  and  of  the  force  of  30 
inches  of  mercury,  in  pressure,  is  to  dry  air  as  10  to  16. — Henry. 

t  See  Dr.  Hare's  experiments,  in  his  Compendium. 

t  For  a  table,  see  Henry,  Vol.  I,  p.  116,  Lon.  Ed.  10. 

§  The  space  above  the  mercury  in  a  barometer  tube  :  it  was  called  after  its  discov- 
erer Evangelista  Torricelli. 

||  The  monks  at  one  of  the  highest  monasteries  on  the  Alps,  complain  that  they 
cannot  make  good  Bouillie,  (milk  porridge,)  because  the  water  boils  so  soon. — Paris' 
Pharmacologia.  A  digester  would  remove  the  difficulty. 

1F  Am.  Jour.  Vol.  XVII.  p.  50. 


HEAT  OR  CALORIC.  89 

degree  near  the  boiling  point  is  divided  into  1000  parts.  Each  de- 
gree of  Fahr.  is  equivalent  to  0.689  of  an  inch  of  the  barometer,  in- 
dicating an  elevation  of  530  feet.  The  1000th  part  of  a  degree  in 
Wollaston's  thermometer  is  therefore  equivalent  to  about  six  inches, 
and  the  height  of  a  common  table  produces  a  manifest  difference 
in  the  boiling  point  of  water.* 

This  delicate  instrument  therefore  answers  the  purpose  of  a  bar- 
ometer, it  being  necessary  only  to  make  water  boil  in  order  to  deter- 
mine the  elevation  of  the  place. 

The  boiling  point  of  water  is  raised  by  having  salt  dissolved  in  it, 
and  the  steam  has  the  temperature  of  the  boiling  fluid,  and  so  in  other 
cases.f 

(o.)  Slight  variations  of  pressure  may  be  exhibited  in  glass  vessels. 
— Boil  water  in  a  flask  until  the  air  is  all  expelled  by  the  steam  ; 
cork  it  while  boiling ;  if  tight,  it  will  continue  to  boil,  and  the  more 
rapidly,  if  it  be  cooled,  as  by  touching  it  with  or  immersing  it  in  cold 
water,  and  the  boiling  will  be  repressed  or  stopped  by  hot  water. 

In  a  retort  corked  in  the  same  manner,  the  same  phenomena  are 
still  more  strikingly  exhibited ;  the  water,  if  shaken  after  all  is  cold, 
falls  like  lead,  thus  illustrating  the  principle  of  the  water  hammer.f 

Water,  boiled  in  a  flask,  furnished  with  a  stop  cock,  has  its  ebulli- 
tion repressed  by  closing  the  key  for  a  very  short  time ;  on  opening 
it,  it  boils  violently  again,  and  so  vice  versa.  This  must  be  done 
with  caution,  the  operator  avoiding  exposure  both  to  the  mouth  and 
bottom  of  the  vessel.  All  these  effects  depend  on  variations  of  pressure. 

(P.)  GREAT  VARIATIONS  OF  PRESSURE  ARE  SAFELY  EXHIBITED 

IN  STRONG  METALLIC  VESSELS. 

In  Papin's  digester,  or  any  strong  boiler,  fitted  with  a  cover,  stop- 
cocks and  valve,  the  vapor  of  boiling  water  or  other  fluids  may 
be  confined ;  then  the  temperature  of  the  fluid  will  rise  as  the  pres- 
sure increases,  and  the  ebullition  will  be  repressed  or  stopped.  Wa- 
ter may  be  heated  in  this  manner  to  400°  of  Fahr.  or  more ;  the 
danger  of  explosion  is  of  course  greater  in  proportion  to  the  heat  ;§ 
the  machine  being  suddenly  opened,  a  jet  of  steam  rushes  out  with 
great  violence,  and  the  temperature  of  the  water  falls. 

Mr.  Southern's  table  of  pressure  and  temperature  is  copied  from 
Henry.  || 

•  Henry,  and  Phil.  Trans.  t  Eng.  Quar.  Jour.  Vol.  XVIII. 

t  This  is  owing  to  the  want  of  atmospheric  resistance,  and  shews  that  rain  would 
fall  like  shot  if  it  were  not  resisted  hy  the  air. 

§  As  formerly  helieved,  although  now  controverted  by  Mr.  Perkins  ;  see  Jones' 
Journal,  and  American  Jour.  Vol.  XIII,  p.  52.  Mr.  Perkins  thinks  that  the  pres- 
sure of  steam  will  not  be  in  proportion  to  the  temperature,  unless  there  be  an  abund- 
ant supply  of  water  to  generate  new  steam  and  thus  add  to  the  quantity.  Aside 
from  this,  the  steam  is  no  more  expanded  "by  increased  heat,  than  air  or  any  other 
elastic  fluid  would  be.  ||  Vol.  I,  p.  122,  Lond.  Ed.  10. 

12 


90  HEAT  OR  CALORIC. 

Pressure  in  inches  Temperature* 

Atmospheres.  of  mercury.  P'ahr. 

1  29.8  -  212.0 

2  -  -    59.6     -  -       250.3 
4                              -       179.2  -  293.4 
8     -                               238.4     -                             -       343.6 

(q.)  The  latent  heat  of  steam  may  be  shewn  by  the  digester. — Five- 
gallons  of  water  are  heated  to  400°  ;  the  orifice  being  opened,  one 
gallon  flies  away  in  the  form  of  steam  ;  the  resulting  temperature  is 
212°  ;  therefore  one  gallon  in  steam  has  carried  away  heat  repre- 
sented by  5  X  188  —  940=  nearly  the  latent  heat  of  steam;  for  400C 
—  212  -- 188,  and  there  were  five  gallons  of  water. 

(r.)  The  latent  heat  of  condensed  steam,  if  suffered  to  pads  into 
cold  water,  makes  it  boil  quickly,  and  it  soon  melts  ice. — Great  noise 
is  produced  by  steam  striking' cold  water;  this  is  owing  to  its  sud- 
den condensation,  and  the  noise  grows  less  as  the  water  becomes 
hotter,  till  finally  the  steam  passes  almost  silently  through  water,  at  or 
near  212°,  like  a  gas,  and  is  not  condensed.* 

The  better  way  to  heat  water,  is  to  surround  by  steam,  the  vessel 
containing  the  water  to  be  heated.  Mr.  Parkes  heated  twenty  gal- 
lons in  this  manner,  in  six  minutes,  from  52°  to  190°,  in  eight  minutes 
to  200°,  in  ten  minutes  to  208°,  and  in  eleven  to  212°. — L.  u.  K.f 

High  steam  does  not  scald,  because  it  is  cooled  by  its  sudden  ex- 
pansion, and  it  blows  along  with  it  a  mass  of  cold  air  ;  indeed  it  is  no 
longer  high  steam,  but  common  steam  partly  condensed.  It  also  blows 
a  burning  brand  powerfully,  but  if  held  too  near,  it  extinguishes  the 
fire  in  consequence  of  the  condensation  of  the  steam  ;  it  does  not 
scald  the  hand,  at  a  few  inches  from  the  orifice.  The  agent  in  the 
combustion  is  not  so  much  the  steam  as  the  air  which  it  blows  along ; 
still,  at  a  very  high  temperature,  the  steam  may  be,  and  probably  is 
decomposed,  giving  oxygen  to  the  carbon,  and  hydrogen  to  the  flame. 

There  is  a  popular  impression  that  a  boiling  tea  kettle  does  not 
burn  the  hand,  but  that,  if  it  ceases  boiling,  it  will  produce  that  effect ; 
perhaps  there  is  a  mistake  in  the  fact ;  and  this  is  the  more  proba- 
ble, as  the  trial  is  of  course  made  in  a  hurried  and  imperfect  manner. 

(s.)  The  density  of  steam  confined  over  water,  is  directly  as  its 
elasticity ;  that  is,  the  higher  the  temperature  and  the  greater  the 
elasticity,  the  greater  is  the  quantity  of  water  contained  in  steam  of 
the  same  volume.  J 


*  It  is  said  however  that  water  heated  in  this  way  is  still  two  or  three  degrees 
short  of  the  boiling  point. — L.  tr.  K. 
t  Quoting  Parkes'  Chern.  Essay. 
t  Henry,  Vol.  I,  p.  122,  Lond.  Ed.  10, 


HEAT  OR  CALORIC.  91 

(T.)  "  The  same  weight  of  steam  contains,  whatever  may  be  its 
density,  the  same  quantity  of  caloric  ;  its  latent  heat  being  increased, 
in  proportion  as  its  sensible  heat  is  diminished  ;  and  the  reverse."* — 
Henry. — Water  distilled  in  vacuo  at  70°,  gave  a  vapor  which,  when 
condensed,  indicated  latent  heat  amounting  to  1200°  or  1300°. 
Hence  there  is  no  economy  of  heat  in  distilling  in  vacuo,  for,  as  the 
sensible  heat  is  diminished,  the  latent  heat  is  increased. 

(U.)  But  steam  formed  at  temperatures  above  212°,  suffers  a  di- 
minution of  latent  heat  by  the  increase  of  its  sensible  heat.^ — Hence 
there  is  no  economy  of  fuel  in  the  use  of  high  steam,  for  more  heat 
passes  off  by  the  chimney  than  where  low  steam  is  generated.  There 
may  be  convenience  and  economy  of  room  and  money,  in  the  ar- 
rangements of  the  machinery,  and  obviously  the  higher  the  temper- 
ature at  which  the  steam  is  formed,  the  more  of  it  there  is  in  a  given 
space,  or  the  more  water  in  the  state  of  steam,  and  consequently  the 
greater  is  the  moving  power. 

(V.)  Fluids  under  vast  pressure,  maybe  converted  into  vapor  with 
only  a  small  augmentation  of  volume. — This  was  done  by  M.  de  la 
Tour,{  in  glass  tubes ;  alcohol  of  thesp.  gr.  .837,  and  occupying  about 
|  of  the  capacity  of  the  tube,  became  transparent  vapor  by  expand- 
ing to  a  little  over  three  times  its  first  volume,  and  with  a  pressure  of 
119  atmospheres,  or  785  Ibs.  on  the  square  inch;  the  temperature 
was  404.6°  Fahr. 

Ether  at  369°  of  Fahr.  became  vapor,  under  38  or  39  atmos- 
pheres =  576  Ibs.  to  the  square  inch,  and  the  vapor  occupied  less  room 
than  that  of  alcohol  or  naptha. 

Water,  with  a  trace  of  carbonate  soda,  required  a  little  over  four 
volumes  to  become  vapor.  In  these  experiments,  the  presence  or 
absence  of  atmospheric  air  made  no  difference,  and  on  cooling  the 
tubes,  the  fluids  reappeared,  the  vapor  being  condensed. 

At  these  high  temperatures,  water  can  decompose  glass,  by  sepa- 
rating its  alkali,  and  thus  causing  the  glass  to  become  cloudy. 


*  That  is,  e  converse,  as  the  sensible  heat  increases,  the  latent  heat  diminishes,  so 
that  equal  weights  of  steam  incumbent  over  water,  at  whatever  temperature,  contain 
the  same  quantity  of  heat;  or  the  total  heat  of  steam  is  a  constant  quantity.  A  giv- 
en quantity  of  vapor  of  the  same  substance,  whatever  may  be  its  temperature,  and 
e-lasticitj  imparts  to  cold  water  the  same  quantity  of  heat 

t  Manchester  Memoirs,  Vol.  II,  now  series.  Brewster's  Edit,  of  Prof.  Robinson's 
works. 

;  Annales  de  Chimie  and  de  Physique,  XXI.  127—178.  XXII.  400.  Annals  of 
Philos.  V.  290. 


HEAT  OR  CALORIC. 


(W.)  OF  THE  STEAM  ENGINE. — Dr.  Hare. 

The  principle  of  Savarifs  Steam  Engine  illustrated, 


i 


"  A  matrass,  situated  as  in  the  above  figure,  and  containing  a  small 
quantity  of  water,  being  subjected  to  the  flame  of  a  lamp,  the  water 
will  soon,  by  boiling,  fill  the  matrass  with  steam.  When  this  is  ac- 
complished, bubbles  of  air  will  cease  to  escape  from  the  neck  of  the' 
matrass,  through  the  water  in  the  vase." 

"The  apparatus  being  thus  prepared,  on  removing  the  lamp,  the 
water  of  the  vase  will  quickly  rush  into  the  vacuity,  in  the  matrass, 
arising  from  the  condensation  of  the  steam." 

Of  Savary' s  Engine.* 

"The  celebrated  engine  of  Savary,  which  led  to  the  invention  of 
that  of  Newcomen,  and  finally  to  the  almost  perfect  machine  of  Bol- 
ton  and  Watt,  consisted  essentially  of  a  chamber  in  which  steam, 
after  being  introduced  from  a  boiler,  was  condensed  by  a  jet  of  cold 
water,  as  in  the  experiment  above  described." 

"Just  before  the  condensation  of  the  steam,  the  communication 
with  the  boiler  was  cut  off,  and  a  cock  or  valve,  was  opened  in  a  pipe 
descending  into  a  reservoir  of  cold  water.  The  chamber  was  con- 
sequently filled  with  water,  which  was  expelled  through  an  aperture 
opened  for  the  purpose,  by  allowing  the  steam  to  enter  again  above 
the  water.  The  aperture  through  which  the  water  escaped,  and 
that  through  which  the  steam  entered,  being  closed  simultaneously, 
the  operation  of  condensing  the  steam  and  filling  the  chamber  with 


*  The  Marquis  of  Worcester  in  1663  published  in  his  book  (whimsically  entitled,; 
The  Century  of  Inventions,  an  obscure  hint  of  the  contrivance,  which  Savary  car- 
ried into  effect  in  166& 


HEAT  OR  CALORIC.  93 

water  was  reiterated,  as  likewise  in  due  succession  the  other  steps  of 
the  process,  as  above  stated." 

Of  Newcomen's  Engine. 

"  The  great  objection  to  Savary's  engine,  was  the  waste  of  steam 
arising  from  its  entrance,  over  the  water,  into  a  cold  moist  chamber. 
So  great  is  the  power  of  cold  water  in  condensing  steam,  that  had 
the  steam  been  introduced,  below  the  water,  it  could  not  have  been 
expelled  until  ebullition  should  have  been  excited  ;  but  heat,  being; 
propagated  downwards  in  liquids  with  extreme  difficulty,  the  steam 
entering  from  above  was  not  condensed  so  rapidly  as  to  paralyze  the 
engine." 

"  To  diminish  the  very  great  loss  sustained  in  the  engine  of  Sa- 
vary,  Newcomen,  instead  of  causing  the  vacuum  produced  by  the 
condensation  to  act  directly  upon  water,  contrived  that  it  should  act 
upon  a  piston,  moving,  air  tight,  in  a  large  cylinder,  like  a  pump 
chamber.  The  piston  was  attached  to  a  large  lever,  to  the  end  of 
which,  on  the  other  side  of  the  fulcrum,  a  pump  rod  and  a  weight 
were  fastened.  By  the  vacuum  arising  from  the  condensation,  the 
piston,  being  exposed  to  the  unbalanced  pressure  of  the  atmosphere, 
was  forced  down  to  the  bottom  of  the  cylinder,  drawing  up,  of  course, 
the  rod  and  weight  at  the  other  end  of  the  lever." 

"The  cylinder  being  replenished  with  steam,  the  weight  on  the 
beam  drew  up  the  piston  in  the  cylinder,  and  pushed  down  the  pump 
rod,  and  thus  by  the  alternate  admission  and  condensation  of  steam, 
the  piston  and  pump  rod  were  made  to  undergo  an  alternate  motion, 
by  which  the  pump,  actuated  by  the  rod,  was  kept  in  operation. — 
Although  less  caloric  was  wasted  by  Newcomen's  engine  than  by 
Savary's,  there  was  still  great  waste,  as  the  cylinder  was  to  be  heated 
up  to  the  boiling  point  each  time  that  steam  was  admitted,  and  to 
be  cooled  much  below  that  point  as  often  as  condensation  was  ef- 
fected." 

In  Watt  and  Bolton's  Engine,*  steam  from  the  boiler  lifts  the  pis- 
ton, and  steam  let  in  above,  depresses  it ;  condensation  of  the  steam 
taking  place  at  the  same  time,  by  communication  with  a  cold  vacuum,, 
connected  with  an  air  pump  ;  thus  the  stroke  and  condensation  are 
alternate,  the  cylinder  is  kept  constantly  hot,  and  the  condenser  coldy 
by  water  pumped  in  by  the  working  machinery,  from  below ;  the 
hot  water,  formed  from  the  condensed  steam,  is  returned  to  the  boiler. 


*  This  engine,  the  most  splendid  present  ever  made  by  science  to  the  arts,  is,  ic 
common  with  other  steam  engines,  far  from  using  the  whole  power  that  is  genera- 
ted ;  for  Clement  and  Desormes  conclude,  from  their  own  experiments  that  the 
best  steam  engines  have  brought  to  bear  not  more  than  one  twelfth  part  of  the 
power  of  steam,  as  calculated  by  theory.— Then.  I.  85,  5th  Edit. 


§4  HEAT  OR  CALORIC. 

by  the  operation  of  the  machinery ;  the  atmosphere  does  not  ope 
rate,  except  on  the  horizontal  section  of  the  rod  of  the  piston.  In 
this  machine,  the  steam  is  constantly  working,  while  in  Newcomen's 
it  was  inert  half  the  time,  and  not  only  was  the  cylinder  below  the 
piston,  chilled  at  every  stroke,  by  the  cold  water,  but  above  the  pis- 
ton, by  the  cold  air.  Mr.  Watt's  great  improvement  consisted  in  shut- 
ting out  the  atmosphere  entirely,  and  in  causing  the  condensation  of 
the  steam,  at  a  distance  from  the  cylinder,  which  is  in  that  way  main- 
tained at  the  boiling  point.  Thus  both  the  upward  and  downward 
movement  of  the  piston,  is  caused  by  the  elastic  effort  of  the  steam. 

Wolf's,  Evans's  or  the  high  Pressure  Engine. — There  is  no  con- 
densation of  the  steam,  which  is  driven  out  alternately,  above  and  be- 
low the  piston,  against  the  atmosphere.  As  these  engines  work  simply 
by  dead  lift  of  expansive  steam,  great  strength  is  necessary  in  the 
machinery.  The  principal  advantage  is  in  economy  of  machinery, 
and  room ;  not  of  fuel.  On  account  of  the  strength  and  smaller  size 
of  the  boilers,  explosions  are  less  frequent,  than  in  the  low  press- 
ure engines,  but  they  are  more  destructive.  Dr.  Hare  remarks, 
that  "  the  engines  in  our  steam  boats,  generally  combine  the  two  prin- 
ciples— using  steam  that  will  support  a  weight,  of  from  seven  to  fif- 
teen pounds,  per  square  inch,  and  that  a  true  Bolton  and  Watt  steam 
engine,  having  an  ample  supply  of  water,  cannot  explode  while  the 
safety  valve  is  of  a  proper  size,  and  not  improperly  loaded."* 

Perkin's  Generator.-^ — The  pressure  is  far  beyond  any  thing  here- 
tofore used ;  eight  hundred  pounds,  and  even  one  thousand  pounds, 
on  the  square  inch,  is  not  an  uncommon  pressure  and  fifteen  hun- 
dred has  been  frequently  used.  The  generator  is  very  small ;  it  is 
heated  in  a  furnace ;  there  is  no  boiler,  but  water  is  injected  by  the 
machinery,  as  it  is  wanted,  about  one  gallon  at  a  time.  At  Woolwich 
of  late,J  the  steam  was  so  heated,  as  to  set  fire  to  wood,  tow,  &c. 
and  to  ignite  the  iron  generator,  at  the  orifice  made  for  the  emission 
of  the  steam.  Mr.  Perkins  says,  that  4000  atmospheres  =  6 5, 000 
Ibs.  on  the  square  inch,  is  the  maximum  pressure  of  steam.<§ 

(#.)  Mr.  Perkins  states  that  his  high  steam  will  not  issue  from  an 
orifice,  in  his  generator,  one  fourth  of  an  inch  in  diameter,  the  pressure 


*  If  these  conditions  were  observed,  all  steam  engines  would  be  much  safer  than 
they  are  ;  but  in  the  high  pressure  engines,  the  metal  is  necessarily  exposed  both 
to  the  weakening  effect  of  heat,  and  to  the  mechanical  strain  arising  from  vast  pres- 
sure ;  while  in  the  low  pressure  engines,  these  causes  are  comparatively  feeble  in 
their  operation.  The  rule  for  loading  the  valve  in  Mr.  Watt's  original  engines, 
was  two  and  a  half  pounds  for  each  square  inch. 

t  See  Am.  Jour,  especially  Vol.  XIII. 

t  Jones'  Journal,  Nov.  1827. 

§  The  elastic  energy  of  common  steam  is  derived  from  the  latent  heat  X  ^P-  gr.  -{- 
the  temperature  or  thermometric  tension. —  Ure. 


HEAT  OR  CALORIC.  95 

being  SOOlbs.  on  the  square  inch,  but  when  cooled  down  to  the  com- 
mon working  temperature,  it  issues  with  a  roaring  noise,  so  as  to  be 
heard  ii:  U  a  mile,  and  powerfully  blows  a  burning  brand  which  it 
would  not  do  before.* 

(y.)  Cause  of  >h.e  explosion  of  steam  boilers. — According  to  Mr. 
Perkins  and  Mr.  Hazard,  of  Philadelphia,  it  is  caused  mainly  by  the 
fact  that  the  boiler,  by  want  of  water,  becomes  heated  unduly,  and 
heats  the  steam  excessively  ;  the  water  then  dashing  up  in  jets,  caus- 
ed by  the  ebullition,  or  even  by  the  spontaneous  or  intentional  lifting 
of  the  valve,  is  converted  into  steam,  in  such  great  quantities,  that  it 
cannot  be  retained,  and  therefore  bursts  the  boiler.  A  boiler  full  of 
steam,  without  access  to  water,  it  is  said,  may  be  heated  even  to  red- 
ness, without  explosion,  steam  being  no  more  expansible  than  an 
equal  volume  of  air,  but  if  there  be  water  present  to  form  more 
steam,  then  the  pressure  becomes  uncontrolable.  Red  hot  iron  boil- 
ers, by  decomposing  water,  doubtless  generate  hydrogen  gas,  when 
the  water  is  suddenly  let  in,  and  this,  being  incapable  of  condensa- 
tion, of  course,  greatly  increases  the  tendency  to  explosion,  which 
the  boiler,  thus  rapidly  oxidized,  is  unable  to  resist. 

STEAM    ARTILLERY. 

Mr.  Perkins,  by  applying  steam  to  the  propulsion  of  cannon  balls, 
is  able  to  throw  sixty,  four-pound  balls,  in  a  minute,  "  with  the  cor- 
rectness of  a  rifled  musket,  and  to  a  proportionate  distance." 

A  musket  may  be  made  to  throw,  by  means  of  steam,  from  one 
hundred  to  one  thousand  balls  in  a  minute,  and  it  is  not  doubted  that 
a  constant  stream  of  balls  may  be  discharged  during  a  whole  day,^ 
if  required.  From  five  hundred  to  one  thousand  bullets  have  actu- 
ally been  thrown  per  minute,  the  steam,  all  the  while  blowing  off  at 
the  escape  valve. f  It  is  said,  however,  that  the  range  of  shot,  pro- 
pelled by  steam,  is  much  more  limited  than  if  fired  in  the  usual  way. 
Principle  of  Cupping. 

A  cup  partially  exhausted  of  air,  by  burning  paper  in  it,{  and  sud- 
denly applied  to  the  soft  parts  of  the  body,  allows  the  flesh  to  be  forced 
into  it,  by  atmospheric  pressure,  and  after  scarification,  the  renewal 
of  the  process,  causes  the  blood  to  ooze  out.  The  emission  of  blood, 
at  great  heights,  as  experienced  by  Humboldt  and  his  companions 
on  the  Andes,  was  probably  owing  to  the  prevailing  force  of  vas- 
cular action,  under  a  greatly  diminished  pressure,  on  the  surface  of 
the  body. 


*  Mr.  Perkins  supposes  that  heat  is  matter  and  that  its   accumulation  at  the 
fice  imprisons  the  steam. 

t  Am.  Jour.  Vol.  XIII.  pp.  44,  45. 

-  Exhausting  syringes  are  said  to  be  now  occasionally  used. 


HEAT  OK  CALORIC. 


A 


ADDITIONAL    EXPERIMENTAL     ILLUSTRATIONS     OF    THE    NATURE     OF 
AERIFORM    BODIES. 

1.  Aeriform  bodies  can  displace  gross  fluids  or  pre- 
vent their  entrance  into  cavities  which  they  occupy. — 
The  figure  represents  a  cylindrical  glass  containing  a 
colored  fluid,  upon  which  is  a  taper  floating  upon  a 
wide,  flat  and  thin  cork ;  a  narrow  and  tall  bell  glass 
is  placed  carefully  over  the  light,  and  depressed  as  far 
as  it  can  be,  without  making  the  fluid  overflow ;  the 
light  is  then  seen  at  b  b  which  is  the  surface  of  the 
fluid,  within  the  jar,  while  a  a,  shows  its  position  on  the 
outside.     It  is  hardly  necessary  to  mention  that  this  is 
the  principle  of  the  diving  bell. 

2.  The  candle  bomb  is  a  spherule  of  glass  contain- 
ing a  little  alcohol,  ether  or  water  ;  it  has  a  stem,  which 
is  stuck  into  a  candle,   so  that  the  ball  shall  be  in,  or 
just  above  the  wick,  which  is  touched  with  oil  of  tur- 
pentine, that  it  may  be  lighted  promptly  ;  when  this  is  done,  the  fluid 
is  vaporized,  and  the  glass  soon  explodes ;  it  should  be  placed  behind 
a  screen. 

3.  A  glass  flask  containing  water  over  an  Jlrgand  or  spirit  lamp. 
or  over  a  few  burning  coals,  shews  the  phenomena  of  boiling. 

4.  The  Eolipile. — A  copper  ball  with  a  recurved  tube,  shews  the 
force  of  steam,  issuing  from  a  capillary  orifice  ;  it  will  vigorously 
blow  a  burning  brand,  or  the  entire  fire,  if  placed  on  the  hearth.     If 
ether,  or  alcohol,  or  oil  of  turpentine  be  substituted  for  the  water,  the 
jet  of  vapor  is  then  inflammable.     The  fluid  is  introduced  as  it  is 
into  the  thermometer  ball. 

5.  Ether  is  easily  vaporized. 

(a.)  In  a  flaccid  bladder,  furnished  with  a  stop  cock  and  tube,  let 
a  little  ether  be  heated  by  contact  with  hot  water ;  it  will  soon  in- 
flate the  bladder,  which  being  compressed,  will  give  a  jet  of  inflam- 
mable vapor ;  or  cold  water  applied  to  the  bladder  will  condense  it. 

(b.)  A  tall  thin  glass  jar,  filled  with  water,  and  standing  in  the  pneu- 
matic cistern,  has  a  little  ether  introduced,  by  turning  up  beneath  it,  a 
vial  filled  with  that  fluid :  the  jar  should  be 
secured  by  recurved  tongs,  of  this  form, 
or  by  a  ring  on  a  stand  :  boiling  hot  water, 
from  a  tea  kettle,  being  poured  on  the  top 
of  the  jar,  the  ether  boils,  and  drives  the  water  out  ;  if  the  jar  be 
quickly  lifted  out  of  the  water,  the  etherial  vapor  'may  be  inflamed 
by  a  candle,  or  if  allowed  to  stand,  the  water  will  condense  the  vapor 
and  will  again  fill  the  jar,  except  a  small  space  occupied  by  extract- 
ed air. 


HEAT  OR  CALORIC.  97 

(c.)  Such  a  flask,  as  that  represented  at  No.  11,  p.  100,  is  filled 
with  water,  except  an  inch  or  two  of  the  neck,  which  is  occupied  by 
ether  ;  its  mouth  being  covered  by  the  thumb,  it  is  inverted  and  se- 
cured in  the  pneumatic  cistern,  and  treated  as  in  (6.)  and  with  the 
same  result,  only  the  return*  of  the  water  especially  if  the  neck  of 
the  flask  is  plunged  deep,  so  that  the  water  which  comes  in  is  very 
cold,  may  be  sudden  ;  it  produces  a  violent  whirl  of  the  injected 
water,  which,  if  it  does  not  break  the  flask,  makes  a  very  pleasing 
experiment ;  if,  when  the  etherial  vapor  fills  the  vessel,  the  thumb 
be  used  as  a  stopper,  the  ball  of  the  flask  may  then  be  cooled,  and 
the  water  let  in  gradually,  without  endangering  the  vessel,  but  the 
effect  is  much  less  striking. 

(d.)  Ether  boils  instantly  at  the  common  temperature,  in  the  Tor- 
ricellian vacuum. — Form  this  vacuum  by  using  a  strong  tube,  thirty- 
three  or  thirty-four  inches  long,  and  a  half  or  three  quarters  of  an  inch 
in  the  bore,  and  then  introduce  a  little  ether  through  the  mercury,  in 
which  the  tube  stands,  by  depressing  a  small  essence  vial  full 
of  that  fluid,  beneath  the  mouth  of  the  tube,  and  turning  it  up  ;  as 
soon  as  the  ether  arrives  near  the  top  of  the  tube,  it  flashes  into 
vapor,  with  violent  ebullition  and  drives  the  mercury  half  or  two 
thirds  down  the  tube  ;  if  the  tube  be  then  inclined  in  a  position  as 
nearly  horizontal  as  possible,  without  removing  its  mouth  from  the 
mercury,  a  great  part  of  the  ether  will  be  recondensed,  and  the  va- 
por will  be  formed  anew  on  raising  the  tube. 

The  above  experiment  is  very  strikingly  exhibited  by  filling  the  tube 
with  mercury,  except  an  inch  at  the  top,  which  is  filled  with  ether, 
and  then  the  orifice  being  closed  with  the  thumb  or  the  hand,  it  is 
introduced,  in  an  inverted  position,  into  the  mercurial  cistern,  when 
as  soon  as  the  hand  is  withdrawn,  the  tube,  at  that  moment  occupied 
by  the  mercury  and  ether,  becomes  instantly,  in  a  great  measure 
filled  with  etherial  vapor,  which,  as  before,  drives  the  mercury  down. 

6.  A  glass  tube,  six  or  eight  feet  long,  and  one  inch  wide,  closed  at 
one  end,  and  the  other  fitted  with  a  stop-cock,  being  screwed  to  the 
plate  of  the  air  pump,  may  be  exhausted  to  the  greatest  degree  that 
the  pump  is  capable  of;  if  the  pump  is  a  good  one,  the  atmosphere, 
when  the  tube  is  unscrewed  and  opened  beneath  water,  will  force 
it  up  in  a  jet  and  nearly  fill  it :  a  colored  fluid  gives  the  most  beauti- 
ful experiment. 

7.  If  the  exhausted  tube  be  opened  under  mercury,  a  jet  of  that 
fluid  will  be  thrown  in,  and  the  column  that  is  formed  may  be  thirty 
inches  high.     On  lifting  the  tube  out  of  the  mercurial  cistern,  the 
atmosphere  will  enter,  and,  because  there  is  still  a  good  vacuum 
above  the  mercury,  the  latter  fluid  will  be  pushed  up  nearly  or  quite, 
to  the  top  of  the  tube,  and  will  then  fall,  and  the  same  effect  will 

13 


98 


HEAT  OR  CALORIC. 


be  exhibited  several  times,  but  each  time  in  a  diminishing  degree, 
until  it  ceases. 

8.  CULINARY  PARADOX. 

Ebullition  by  Cold*— Dr.  Hare,  8  to  14. 

"  A  matrass,  half  full  of  water,  being 
heated  until  all  the  contained  air  is  ex- 
pelled by  steam ;  the  orifice  is  closed 
so  as  to  be  perfectly  air  tight.  The 
matrass  is  then  supported  upon  its  neck, 
in  an  inverted  position,  by  means  of  a 
circular  block  of  wood.  A  partial  con- 
densation of  the  steam  soon  follows, 
from  the  refrigeration  of  that  portion 
of  the  glass  which  is  not  in  contact 
with  the  water.  The  pressure  of  the 
steam  upon  the  liquid  of  course  be- 
comes less,  and  its  boiling  point  is  ne- 
cessarily lowered.  Hence  it  begins 
again  to  present  all  the  phenomena  of 
ebullition  ;  and  will  continue  boiling, 
sometimes  for  nearly  an  hour." 

"  By  the  application  of  ice,  or  of  n 
sponge  soaked  in  cold  water,  the  ebullition  is  accelerated  ;  because 
the  aqueous  vapor,  which  opposes  it,  is  in  that  case  more  rapidly 
condensed  :  but  as  the  caloric  is  at  the  same  time  more  rapidly  ab- 
stracted from  the  water,  by  the  increased  evolution  of  vapor,  to  re- 
place that  which  is  condensed,  the  boiling  will  cease  the  sooner." 


*  This  fact  is  pleasingly  exhibited,  by  providing  two  cylindrical  glass  vessels,  of 
one  quart  or  two  in  capacity,  (the  quart  or  three-pint  tumblers,  sold  in  the  shops, 
answer  very  well) ;  into  one  of  them  pour  cold,  and  into  the  other  hot  water  ;  then 
immerse  alternately  in  each,  a  flask  which  contains  water  that  was,  just  before, 
while  boiling,  cut  off,  by  a  good  cork,  from  the  atmosphere ;  in  the  cold  water  it 
will  boil  vehemently,  and  in  the  hot  it  will  cease  boiling. 

A  retort  if  treated  in  a  similar  manner,  is  a  still  better  instrument,  because  it  pre- 
sents in  the  ball,  a  large  surface  for  warming  or  cooling;  and  a  little  cold  or  hot 
water  poured  on  cautiously,  while  the  retort  is  hanging  in  a  ring,  produces  a  very 
striking  effect.  If  the  retort  be  very  thin,  and  especially  if  large,  there  is  danger  of 
its  being  crushed  by  the  pressure  of  the  atmosphere.  I  have  repeatedly  met  with 
this  accident,  with  both  retorts  and  flasks  $  but  it  is  not  dangerous,  as  the  fragment 
do  not  fly  about. 


HEAT  OR  CALORIC. 


9.  AERIFORM  STATE  DEPENDENT  ON  PRESSURE. 


FIG.   1. 


Proof  that  some  Liquids  would  always  be  aeri- 
form, were  it  not  for  the  Pressure  of  the 
Atmosphere. 

"A  glass  flask,  fig.  1,  being  nearly  filled 
with  water,  and  having  the  remaining  space 
occupied  by  sulphuric  ether,  is  inverted  in  a 
glass  jar,  covered  at  bottom  by  a  small  quan- 
tity of  water,  to  prevent  the  air  from  entering 
the  neck  of  the  flask.  The  whole  being  placed 
upon  the  air  pump  plate,  under  a  receiver, 
and  the  air  exhausted,  the  ether  assumes  the 
aeriform  state,  and  displaces  the  water  from 
the  flask.  Allowing  the  atmospheric  air  to  re- 
enter  the  receiver,  the  ethereal  vapor  is  con- 
densed into  its  previous  form,  and  the  water 
reoccupies  its  previous  situation  in  the  flask." 


FIG.  2. 


"  The  return  of  the  ether,  to  the  fluid  state, 
is  more  striking,  when  mercury  is  employed,  as 
in  fig.  2  ;  though,  in  that  case,  on  account  of 
the  great  weight  of  this  metallic  liquid,  the 
phenomenon  cannot  be  exhibited  on  so  large  a 
scale,  without  endangering  the  vessels,  and 
risking  the  loss  of  the  mercury."* 


*  It  is  pleasing  to  see  so  dense  a  fluid  as  mercury,  especially  as  it  is  also  brilliant 
andopake,  becoming  a  truly  transparent,  invisible,  and  elastic  vapor,  and  then  by  a 
slight  depression  of  temperature,  returning  again  to  the  fluid  state.  The  boiling  of 
the  mercury  in  the  thermometer  ball  and  tube,  during  the  construction  of  that  in- 
strument, exhibits  this  fact  in  perfection. 


100 


HEAT  OR  CALORIC. 


10.  Atmospheric  pressure  opposes  and  limits  chemical  action,  where 
elastic  fluids  are  to  be  generated  or  evolved. 

"  Water  would  boil  at  a  lower  temperature  than  212°,  if  the  at- 
mospheric pressure  were  lessened  ;  for  when  it  has  ceased  to  boil  in 
the  open  air,  it  will  begin  to  boil  again  in  an  exhausted  receiver ; 
and  those  who  ascend  mountains  find,  that  for  every  five  hundred 
and  thirty  feet  of  elevation,  the  boiling  point  is  lowered  one  degree 
of  Fahrenheit's  thermometer." 


The  boiling  point  is  lowered  by  a  diminution 
of  atmospheric  pressure. 

"  Water  heated  to  ebullition  in  a  glass  ves- 
sel, having  ceased  to  boil  in  consequence  of  its 
removal  from  the  fire,  will  boil  again  under  a 
receiver,  as  soon  as  the  air  is  withdrawn." 


1 1 .  Boiling  point  raised  by  pressure. 

Jls  the  Boiling  Point  is  lowered  by  diminution  of  Pressure,  so  it  is 
raised  if  the  Pressure  be  increased. 

"  Into  a  small  glass  matrass,  with  a  bulb, 
of  about  an  inch  and  a  half  in  diameter, 
and  a  neck  of  about  a  quarter  of  an  inch 
in  bore,  introduce  nearly  half  as  much 
ether  as  would  fill  it.  Closing  the  orifice 
with  the  thumb,  hold  the  bulb  over  the 
flame  of  a  spirit  lamp,  until  the  effort  of 
the  generated  vapor  to  escape,  becomes 
difficult  to  resist.  Removing  the  matrass, 
to  a  distance  from  the  lamp,  lift  the  thumb 
from  the  orifice  :  the  ether,  previously  qui- 
escent, will  rise  up  into  a  foam,  produced 
by  the  rapid  extrication  of  its  vapor." 

"  This  experiment  may  be  performed 
more  securely,  by  employing  a  vessel  of 
hot  water,  instead  of  a  flame,  to  warm  the  matras«," 


HEAT  OR  CALORIC.  101 

12.   Column  of  Mercury  raised  by  vaporized  Ether. 

Jin  increase  of  Pressure  results  from  constrained 
Ebullition. 

"  Having  supplied  a  small  flask  with  a  little 
mercury,  and  a  minute  portion  of  sulphuric 
ether  :  through  the  neck,  let  there  be  a  glass 
tube,  so  introduced,  and  firmly  luted,  as  that  it 
may  be  concentric  with  the  vertical  axis  of  the 
vessel,  and  extend  downwards  until  nearly  in 
contact  with  the  bottom.  If  the  flask  thus  pre- 
pared, be  held  cautiously  over  a  spirit  lamp,  the 
ether  will  be  more  or  less  converted  into  vapor. 
The  vapor  being  unable  to  escape,  will  soon 
cause  the  mercury  to  rise  to  the  top  of  the  tube. 
On  the  removal  of  the  lamp,  the  mercury  gradu- 
ally falls  to  its  previous  situation." 

It  is  better,  as  Dr.  Hare  has  before  recom- 
mended, to  plunge  the  flask  cautiously  into  hot 
water  (of  about  150',  or  180°,)  as  the  pressure 
sometimes  blows  out  the  bottom  of  the  flask, 
when,  if  over  fire,  a  dangerous  combustion  would 
ensue. 

13.  HIGH  PRESSURE  BOILER. 

That  the  temperature  of  Steam  is  directly  as  the  pressure,  may  be 
demonstrated  by  a  small  Boiler,  such  as  is  represented  in  the  fol- 
lowing cut. 

"  The  glass  tube  in  the  axis,  passes  below  the  water  in  the  boiler, 
and  enters  a  small  quantity  of  mercury  at  the  bottom.  The  junc- 
ture of  the  tube,  where  it  enters  the  boiler,  is  made  perfectly  tight. 
On  the  opposite  side  of  the  boiler,  a  tube,  not  visible  in  the  draw- 
ing, descends  into  it.  This  tube  consists  of  about  two  inches  of  a 
musket  barrel,  and  is  closed  at  bottom.  The  object  of  it  is  to 
contain  some  mercury,  into  which  the  bulb  of  a  thermometer  may  be 
inserted,  for  ascertaining  the  temperature." 

"  When  the  fire  has  been  applied  during  a  sufficient  time,  the 
mercury  will  rise  in  the  glass  tube,  so  as  to  be  visible,  above  the 
boiler  ;  and  continuing  to  rise,  during  the  application  of  the  fire,  it 
will  be  found  that  with  every  sensible  increment  in  its  height,  there 
will  be  a  corresponding  rise  of  the  mercury  in  the  thermometer. 
In  front  of  the  tube,  as  represented  in  the  figure,  there  may  be  ob- 
served a  safety  valve,  with  a  lever  and  weight,  for  regulating  the 
pressure." 


102 


HEAT  OR  CALORIC. 


"  It  has  been  found,  that  when  the  effort  made  by  the  steam  to 
escape,  in  opposition  to  the  valve  thus  loaded,  is  equal  to  about  fif- 
teen pounds  for  every  square  inch,  in  the  area  of  the  aperture,  the 

height  of  the  column  of  mer- 
cury, C,  C,  raised  by  the  same 
pressure,  is  about  equal  to  that 
of  the  column  of  this  metal, 
usually  supported  by  atmos- 
pheric pressure,  in  the  tube 
of  a  barometer." 

"  Hence  the  boiler,  in  this 
predicament,  is  conceived  to 
sustain  an  unbalanced  press- 
ure equivalent  to  one  atmos- 
phere, and  for  every  additional 
fifteen  pounds  per  square  inch, 
required  upon  the  safety  valve 
to  restrain  the  steam,  the 
pressure  of  an  atmosphere  is 
alleged  to  be  added.  To  give 
to  steam  at  212°,  or  the  boil- 
ing point,  such  an  augmenta- 
tion of  power,  a  rise  of  38° 
is  sufficient,  making  the  tem- 
perature equal  to  250°.  To 
produce  a  pressure  of  four  at- 
mospheres, about  293°  would 
be  necessary.  Eight  atmos- 
pheres would  require  nearly 
343°." 

"  When,  by  means  of  the 
cock,  an  escape  of  steam  is 
allowed,  a  corresponding  de- 
cline of  the  temperature  and 
pressure  ensues." 

"  If  the  steam,  as  it  issues 
from  the  pipe,  be  received  un- 
der a  portion  of  water  of  known 
temperature  and  weight,  the 
consequent  accession  of  heat 
will  appear  surprizingly  great, 
when  contrasted  with  the  ac- 
cession of  weight,  derived  from 
the  same  source. — It  has  in 
fact  been  ascertained,  that  one 


HEAT  OR  CALORIC. 


103 


measure  of  water  converted  into  aqueoils  vapor,  will,  by  its  conden- 
sation, raise  about  nine  measures  of  water  in  the  liquid  form,  one 
hundred  degrees." 

14.  EXPLOSIVE  POWER  OF  STEAM. 

"  If  a  small  glass  bulb,  hermetically  sealed, 
while  containing  a  small  quantity  of  water,  be 
suspended  by  a  wire  over  a  lamp  flame,  an 
explosion  soon  follows,  with  a  violence  and 
noise  which  is  surprising,  when  contrasted 
with  the  quantity  of  water,  by  which  it  is  oc- 
casioned. 


"  In  order  to  understand  this,  suppose  that 
the  bulb  were,  in  the  first  instance,  merely  fill- 
ed with  steam,  without  any  water  in  the 
liquid  form.  In  that  case  the  effort  of  the 
steam  to  enlarge  itself,  would  be  nearly  in  di- 
rect arithmetical  proportion  to  the  tempera- 
ture ;  but  when  water  is  present  in  the  liquid 
form,  while  the  expansive  power  of  the  steam, 
previously  in  existence,  is  thus  increased,  more  steam  is  generated, 
with  a  like  increased  power  of  expansion.  It  follows,  that  the  in- 
crements of  heat  being  in  arithmetical  proportion,  the  explosive  power 
of  the  confined  vapor  will  increase  geometrically,  being  actually 
doubled,  as  often  as  the  temperature  is  augmented,  somewhat  less 
than  forty  degrees  of  Fahr." 

•Miscellaneous  uses  of  steam.* 

1.  For  warming  apartments,    especially  large  manufactories. — 
There  is  no  danger  from  fire  ;   the  boiler  may  be  even  in  another 
room,  and  as  the  steam  is  transmitted  in  tubes,  it  is  thus  condensed 
and  gives  out  its  heat. 

"  Every  cubic  foot  in  the  boiler  is  equal  to  heating  two  thousand 
feet  of  space  to  an  average  temperature  of  70°  or  80°,"  and  each 
square  foot  of  surface  of  steam  pipe  will  warm  two  hundred  cubic 
feet  of  space. 

2.  For  drying  muslins  and  calicoes  and  other  goods. — Either  the 
stuffs  are  hung  up  in  rooms  and  dried  by  steam  pipes  giving  a  heat  of 
100°  or  130°,  or  they  are  made  to  pass  around  cylinders  filled  with 
steam.     Delicate  colors,  such  as  scarlet  and  crimson,  formerly  faded 
by  stove  drying,  are  thus  preserved  from  injury,  although  heated  to 
165°,  and  the  people  are  healthy,  which  was  said  not  to  have  been 
the  fact  when  the  rooms  were  warmed  by  stoves. 


Concisely  mentioned  before. 


104  HEAT  OR  CALORIC. 

3.  Gunpowder  is  safely  dried,  in  a  similar  manner. 

4.  By  surrounding  the  vessels  with  steam,  pharmaceutical  extracts 
are  made,  without  injury  to  delicate  principles.     Chemical  precip- 
itates are  sometimes  dried  in  the  same  mode. 

5.  Steam  is  employed  in  bleaching. — Instead  of  boiling  the  stuffs 
with  solution  of  potash,  they  are  steeped  in  that  alkali,  and  then  hung 
up  while  wet,  in  a  chamber  which  is  afterwards  filled  with  steam, 
which  enables  the  alkali  to  dissolve  and  remove  the  coloring  matter 
more  effectually  and  more  rapidly  than  in  the  old  way.* 

6.  It  is  applied  to  cookery. — It  is  neat  and  effectual,  and  the  same 
water  may  in  fact  be  used  twice ;  once  in  the  boiler  as  water,  and 
once,  as  steam,  in  another  vessel,  which  may  be  made  of  tinned  iron, 
and  placed  in  any  convenient  situation,  with  which  a  communication 
should  be  established  by  a  bright  tin  tube  ;  the  boiler  must  be  fur- 
nished with  a  lid  and  a  safety  valve. 

7.  It  is  used  for  heating  baths  and  dye  vats. — The  steam  may  be 
made  to  pass  either  through  tubes,  immersed  in  the  water,  or,  it  may 
be  thrown  directly  into  the  water,  which  it  will  heat  very  rapidly. 
There  should  be  a  valve  in  the  tube  of  communication  to  prevent  the 
reflux  of  the  water  into  the  boiler. 

Very  large  quantities  of  water  may  be  thus  heated  in  vessels  of 
wood,  and  in  one  third  part  of  the  usual  time. 

8.  For  creating  a  vacuum. — This  is  perhaps  more  easily  done 
by  the  action  of  steam  than  in  any   other   way.     The  first   effect 
when  the  steam  engine  is  put  into  operation,  is  to  expel  the  air,  and 
large  vessels  may,  in  this  manner,  be   almost  instantly  filled  with 
steam,  which,  being  quickly  condensed,  leaves  a  pretty  good  vacuum, 
containing  little  else  than  a  feeble  vapor  of  water. 

An  ingenious  still  has  been  constructed  by  Mr.  Barry,  for  making 
vegetable  extracts  in  vacuo ;  both  still  and  receiver  are  freed  from 
air,  and  as  water  will  then  boil  at  a  temperature  below  100°,  the  veg- 
etable extracts  are  obtained  stronger  and  without  empyreuma  or  de- 
composition, f 

(V.)  NATURAL  OR  SPONTANEOUS  EVAPORATION. 

(a.)  This  is  the  gradual  wasting  of  fluids  and  of  some  solids  at 
atmospheric  temperatures. — It  takes  place  at  the  surface,  and  there- 
fore is  not  attended  with  ebullition ;  it  differs  not  at  all  in  principle 
from  vaporization  ;  it  is  only  more  gentle  and  never  produces  any 
agitation. 

Sb.)  Not  only  all  waters,  but  all  animals  and  vegetables  and  men, 
the  entire  surface  of  the  earth  give  out  moisture  by  evaporation. — 
Place  almost  any  thing,  even  ice  itself,  under  an  inverted  glass  which 


*  Murray's  Elements,  6th  Edit.  Vol.  I,  p.  237.        t  Ibid,  p.  143. 


HEAT  OR  CALORIC.  105 

is  kept  cold,  and  vapor  will  be  condensed  in  dew  or  frost  if  the  cold 
be  considerable.  Camphor,  carbonate  of  ammonia,  and  other  vola- 
tile solids  give  off  vapor  so  rapidly,  that  when  placed  in  equilibrio  in 
balances,  they  are  soon  found  to  lose  weight. 

(C.)  The  cause  of  natural  evaporation  is  caloric.  It  produces 
from,  water,  at  every  temperature,  an  elastic  invisible  vapor,  whose 
elasticity  increases  with  the  temperature,  and  which  sustains  a  corres- 
ponding column  of  mercury. — Dalton  and  Gay  Lussac  have  fully  es- 
tablished this  position.  The  theory,  formerly  so  prevalent,  that  evap- 
oration depends  on  the  solution  of  water  in  air,  is  no  longer  tenable 
as  the  sole  and  sufficient  cause,  but  it  is  still  very  possible,*  that  va- 
por may  be  dissolved  in  air.  The  lower  the  boiling  point  of  a  fluid, 
the  more  readily  it  evaporates. 

(d.)  It  has  already  been  stated,  (p.  87  J  that  the  force  of  vapor  is 
the  same  at  the  boiling  point  for  every  fluid  ; — it  equals  thirty  inches 
of  mercury,  and  is  the  same,  in  all  cases,  for  an  equal  number  of 
degrees  above  and  beloiv  ebullition.-\ — This  is  a  curious  fact ;  per- 
haps it  would  have  hardly  appeared  probable,  for  instance,  that  the 
vapor  of  ether  at  its  boiling  point,  98°,  of  water  at  212°,  and  of 
mercury  itself  at  656°,  should  each  exert  a  power  capable  of  sus- 
taining in  a  tube,  a  column  of  that  metal  thirty  inches  in  altitude. 

EFFECTS  OF  NATURAL  EVAPORATION. 

(e.)  Evaporation  produces  cold  because  heat  must  be  absorbed  to 
form  vapor. — The  evaporation  of  ether  under  the  receiver  of  the  air 
pump  freezes  water  in  contact  with  it,  or  having  only  a  thin  vessel 
between  ;  so  a  stream  of  ether  falling  upon  a  thin  glass  tube,  freezes 
water  contained  in  it. 

The  sensation  of  cold  in  coming  out  of  a  bath,  especially  if  warm, 
is  owing  to  the  absorption  of  heat  to  form  vapor.  The  formation  of 
vapor  is  a  cooling  process ;  it  goes  on  extensively,  and  thus  regulates 
natural  temperature.  In  the  hottest  climates,  evaporation  from  ex- 
tensive surfaces  of  water,  mitigates  the  heat,  but  where  there  is  little  or 
no  water,  as  in  the  great  African  desert,  the  heat  becomes  intolerable. 

Excessive  degrees  of  heat  have  been  occasionally  endured  by  hu- 
man beings  in  consequence  of  evaporation  from  their  own  surfaces. 

"  Sir  Joseph  Banks  and  Sir  Charles  Blagden,  breathed  for  some 
time  an  atmosphere  in  a  room  prepared  by  Dr.  Fordyce,  which 


*  Nor  is  it  impossible  or  even  highly  improbable,  that  water  may  be,  to  a  certain  ex- 
tent soluble  in  air,  as  there  is  obviously  an  affinity  between  the  atmospheric  gases 
and  water ;  but  the  fact,  if  admitted,  will  not  account  for  all  the  phenomena,  without 
admitting  the  formation  of  vapor  at  all  temperatures.  It  is  even  said  that  vapor 
formed  at  atmospheric  temperatures,  has  the  same  amount  of  heat  as  that  formed  at 
the  boiling  point;  the  latent  heat  increasing  as  the  sensible  heat  is  diminished. 

t  See  Dalton's  tables. 

14 


106  HEAT  OR  CALORIC* 

was  50°  higher  than  that  of  boiling  water,"  viz.  at  262°  Fahr.  *'  The 
temperature  of  their  bodies  was  not  at  all  raised,  though  their  watch 
chains  and  every  thing  else  metallic  about  their  persons  were  so  heat- 
ed, that  they  could  not  bear  to  touch  them.*  The  thermometers 
which  hung  in  the  rooms  always  sunk  several  degrees  when  either  of 
the  experimentalists  touched  them,  or  breathed  upon  them.  Some 
eggs  and  a  beefsteak  were  placed  on  a  tin  frame  ;  the  eggs  were 
roasted  hard  in  twenty  minutes,  and  the  beefsteak  was  overdone  in 
thirty  three  minutes.  Water  placed  in  the  same  room  did  not  how- 
ever acquire  a  boiling  heat  until  a  small  quantity  of  oil  was  dropped 
on  it,  when  it  soon  began  to  boil  briskly.  The  evaporation  from  the 
surface  of  the  water  had  prevented  it  from  acquiring  the  heat  of  212°  ; 
but  when  that  surface  became  covered  with  a  film  of  oil,  the  evapora- 
could  not  go  on,  and  ebullition  commenced. "f 

"  The  oven  girls  in  Germany  often  sustain  a  heat  of  from  250  to 
280°,  and  one  of  these  girls  once  breathed  for  five  minutes,  in  air 
heated  to  325°  of  Fahr.  When  the  air  of  such  rooms  is  damp,  or  the 
skin  is  rubbed  over  with  varnish,  the  heat  cannot  be  borne  an  instant. "  J 

In  the  case  of  Sir  Joseph  Banks  and  Sir  Charles  Blagden,  it  is 
stated  that  there  was  no  remarkable  evaporation  from  the  skin ;  the 
insensible  perspiration  was  doubtless  greatly  increased,  and  in  such 
cases  an  immense  perspiration  usually  happens,  and  it  is  this  chiefly 
which  either  in  a  sensible  or  insensible  form,  renders  such  trials  safe. 
,  A  well  varnished  man  would  probably  soon  die  in  such  circumstan- 
ces, and  probably  could  not  live  long  at  the  common  temperature.^ 

The  cooling  of  liquors  in  hot  countries,  is  effected  by  evaporation 
from  skins  containing  water,  from  porous  jars,  &c. 

Mr.  Leslie,  with  the  aid  of  sulphuric  acid  to  absorb  the  vapor,  froze 
water  by  its  own  evaporation  under  the  exhausted  receiver ;  some- 
times he  employed  merely  porous  solids,  as  clay,  or  parched  oat  meal 
or  flour,  porous  and  burnt  whin  stone,\\  and  porous,  and  ignited  pieces 
of  muriate  of  lime.lT 

If  the  water  has  been  previously  boiled,  the  ice  formed  is  firmer, 
although  the  process  is  slower.  An  earthen  ware  vessel  is  pre- 

*  "  The  heat  of  metals  at  120°,  is  scarcely  supportable  ;  water  scalds  at  150°,  but 
air  may  be  heated  to  240°,  without  being  painful  to  our  organs  of  sensation." — Davy. 

t  Phil.  Trans.  Vol.  LXXVI,  p.  271,  Ann.  1775.— Quoted  by  Mr.  Parkes.— Es- 
says, 2d  Lond.  Edit.  Vol.  I,  p.  70.  t  Parkes,  quoting  Hist.  Acad.  Sciences,  1764. 

§  Communicated. — Since  reading  "  Wells  on  Dew,"  I  have  doubted  whether  the 
power  of  the  animal  system  to  endure  such  a  high  temperature  were  owing  entirely 
to  the  cooling  effects  of  evaporation.  Physiologists  maintain  that  this  power  of  the 
animal  system  to  endure  a  high  heat,  is  connected  with  the  vital  principle. —  V.  Sir 
Everard  Home,  in  Phil.  Tran. 

||  The  Scotch  colloquial  name  for  greenstone  and  other  trap  rocks. 

IT  The  Pacha  of  Egypt  procured  a  fine  air  pump  for  the  manufacture  of  ice  by  Mr. 
Leslie's  process. 


HEAT  OR  CALORIC.  107 

ferred  for  holding  the  water.  A  hemispherical  earthen  vessel,  con- 
taining three  pints  of  water,  was  placed  by  Mr.  Leslie  over  a  body  of 
parched  oat  meal,  one  foot  in  diameter,  and  one  inch  deep,  and  the 
whole  of  the  water  was  frozen  by  working  the  pump. 

By  the  skilful  management  of  evaporation  and  radiation,  ice  is 
obtained  at  Benares,  in  a  climate  where,  in  the  summer,  the  ther- 
mometer is  never  under  100n,  and  is  often  1 10°. 

Shallow  pits  or  beds  are  made  four  or  five  feet  wide,  and  about 
four  inches  deep,  separated  from  one  another  by  narrow  borders,  and 
so  numerous  as  to  cover  an  extent  of  about  four  acres.  These  pits 
are  filled  with  dry  straw  in  the  middle  of  then1  winter,  when  the  ther- 
mometer is  about  40°  of  Fahr.  On  the  straw  are  placed  rows  of 
shallow  earthen  pans  containing  a  few  inches  of  water  introduced  at 
evening.  In  the  morning  they  find  a  little  ice,  which  at  sun  rise  is 
wrapped  in  flannel  and  carried  to  the  ice  house.  Near  Calcutta,  a 
similar  process  is  adopted.  In  the  plains,  excavations  are  made 
about  thirty  feet  square  and  two  feet  deep,  and  covered  about  a  foot 
deep  with  dried  stalks  of  Indian  corn  or  sugar  cane.  Unglazed 
earthern  pans  about  1 J  inch  deep,  are  filled  with  soft  water  which 
has  been  boiled,  and  in  the  three  winter  months,  some  of  it  is  frozen, 
every  night,  when  the  weather  is  clear.  At  sun  rising  it  is  carried, 
wrapped  in  flannel,  to  the  ice  house,  which  is  a  deep  pit,  lined  with 
straw  and  coarse  blankets,  and  covered  by  a  thatched  roof — the 
mouth  is  closed  with  straw. — L.  u.  K. 

Quicksilver  may  be  frozen  by  the  united  influence  of  evaporation, 
rarefaction  and  absorption. — If  a  pear  shaped  mass  of  ice  containing 
the  metal,  be  suspended  over  a  large  surface  of  sulphuric  acid,  and 
a  good  exhaustion  obtained,  it  will  freeze  the  quicksilver,  which  may 
be  kept  solid  for  several  hours. — L.  u.  K. 

The  freezing  of  wet  clothes  exposed  to  the  air  when  the  thermom- 
eter is  not  so  low  as  32°,  is  occasioned  by  evaporation. 

Plants  are  often  injured  by  the  frost  when  the  thermometer  is  above 
freezing  ;  this  is  the  joint  effect  of  evaporation  and  radiation. 

Wine  coolers  are  usually  made  of  porous  earthern  jars  unglazed  ; 
they  cool  the  wine  by  evaporation  from  the  surface  ;  several  of  them 
on  a  table  have  an  effect  on  the  air  around,  which  is  perceptible  to 
the  guests.  Rooms  are  cooled  by  sprinkling  water  around  them,  in 
hot  weather. 

In  India,  drapery  is  suspended  around  their  dining  halls,  which  are 
roofed,  but  open  at  the  sides,  and  water  being  dashed  on  the  cur- 
tains, the  evaporation  generates  cold. 

(/.)  Evaporation  contributes  to  health,  by  imparting  moisture  to 
the  atmosphere. — The  driest  air  contains  moisture,  which  is  often 
condensed  upon  cold  objects,  especially  if  they  are  good  conductors. 


108  HEAT  OR  CALORIC. 

During  hot  weather,  cold  water,  in  almost  any  vessel,  but  soonest 
in  a  metallic  one,  produces  drops  of  condensed  vapor  upon  the  out- 
side and  a  freezing  mixture  will  generate  hoar  frost  from  the  driest  air. 

If  the  air  were  deprived  entirely  of  moisture,  it  would,  during  res- 
piration, parch  the  membranous  lining  of  the  passages,  and  thus 
produce  great  inconvenience,  and  eventually  serious  mischief,  in 
breathing. 

(g.)  Evaporation  injures  health  by  raising  into  the  air  miasmata, 
produced  by  animal  and  vegetable  putrefaction. — This  is  too  evident 
to  need  illustration  ;  the  effect  is  dependent  on  a  certain  degree  of 
heat,  aided  by  moisture,  as  is  seen  in  the  rice  swamps  of  our  south- 
ern states.  Fever  and  ague*  probably  arise  chiefly  from  this  cause. 
In  cold  countries  extensive  swamps  do  little  or  no  mischief,  and  even 
in  those  that  are  temperate,  they  are  comparatively  harmless.  The 
region  about  the  river  Sorel,  in  Lower,  and  the  Welland  Canal,  in 
Upper  Canada,  are  examples.  In  particular  seasons,  however,  such 
countries  become  sickly. 

(h.)  Evaporation  supplies  the  moisture  necessary  to  form  rmn1 
snow,  hail,  hoar  frost,  dew,  fogs,  mist,  fyc. — This  precipitation  takes 
place  according  to  the  state  of  the  atmosphere  ;  it  is  much  influenc- 
ed by  the  mingling  of  currents  of  air,  differing  in  temperature,  and 
in  the  quantity  of  vapor  they  contain. 

Precipitation  of  dew,  hoar  frost,  &c.  is  much  affected  by  radiation, 
from  the  surface  of  the  earth,  and  this  depends  greatly  on  the  pre- 
valence or  absence  of  clouds. 

Radiation  is  most  abundant  in  a  clear  night,  when  the  temperature 
of  the  ground  is  often  several  degrees  lower  than  that  of  the  air. 
The  frost  is  often  caused,  principally,  by  radiation  from  the  ground ; 
hence,  it  frequently  freezes  on  the  ground  when  the  air  is  not  as  low 
as  32°.  This  subject  has  been  fully  illustrated  by  Dr.  Wells,  and  he 
has  explained,  why  condensation  of  atmospherical  vapor  takes  place 
when  there  is  not  cold  enough  in  the  air  to  produce  it ;  it  is  because 
the  surfaces  on  which  the  vapor  is  precipitated,  are  colder  than  the 
air  ;  those  surfaces  that  radiate  the  best,  will  therefore  be  the  coldest ; 
hence,  glass  will  be  colder  than  metals. 

This  radiation  from  the  earth's  surface  is  of  the  utmost  importance 
to  vegetation,  especially  in  hot  climates ;  plants  radiate  heat  very 
powerfully,  and  hence,  they  are  often  covered  with  dew,  when  the 
naked  ground  is  scarcely  moist.  This  effect  is  much  favored  by 
the  clear,  cloudless  skies,  of  hot  climates,  while  in  colder  regions, 
there  is  more  cloudy  weather.  The  earth  is  there  cold  and  damp  and 


*  Malaria  is  the  classical  word  now  applied  to  all  such  effects,  and  to  their  causee- 
wbether  understood  or  not. 


HEAT  OR  CALORIC.  109 

needs  much  less  moisture — and  there  radiation  is  much  less  ener- 
getic.* 

It  has  been  already  mentioned  that  a  principal  cause  of  the  per- 
manency of  snow  on  high  mountains,  is  the  diminution  of  capacity 
for  heat  in  the  air,  in  consequence  of  its  rarefaction  ;  it  rises  often, 
highly  charged  with  aqueous  vapor,  which  the  cold  precipitates 
abundantly. 

(i.)    Circumstances  which  influence  evaporation. 

Surface'. — As  natural  evaporation  proceeds  from  the  surface  only, 
the  more  extensive  the  surface,  other  things  being  equal,  the  more 
rapid  is  the  evaporation. 

Water  in  a  bottle,  with  a  narrow  open  mouth,  will  waste  away  very 
slowly,  but  the  same  quantity  of  water,  in  a  wide  and  shallow  basin, 
will  evaporate  much  more  rapidly.  In  a  narrow-mouthed  vessel,  also 
the  pressure  of  the  vapor  which  is  formed,  will  react  to  retard  the  evap- 
oration. Agitation  promotes  evaporation  by  enlarging  the  surface, 
and  by  exposing  warmer  particles  successively. 

Temperature. — The  effect  of  increased  temperature  on  evapora- 
tion, is  very  familiar ;  hot  fluids  evaporate  more  rapidly  than  cold 
ones,  in  proportion  as  their  temperature  is  higher. 

Vapor  in  the  air. — As  a  given  temperature  can  raise  only  a  given 
quantity  of  vapor  into  the  air,  it  follows  that  evaporation  will  be  more 
or  less  rapid,  according  as  the  quantity  of  vapor  already  in  the  air, 
is  more  or  less  considerable.  In  a  very  dry  air,  the  evaporation  is 
always  more  rapid  than  in  a  moist  air,  and  when  the  vapor  already 
in  the  atmosphere,  is  the  maximum,  that  the  given  temperature  can 
sustain,  there  will  be  no  evaporation. 

Pressure. — The  principles  that  have  been  established  under  the 
head  of  vapor,  are  applicable  here.  Evaporation  is  more  or  less 
rapid,  as  the  pressure  is  greater  or  less.  Atmospheric  pressure  re- 
tards evaporation  ;  hence,  it  is  remarkably  accelerated  in  the  vacu- 
um of  the  air  pump ;  but  the  same  quantity  of  vapor  is  raised  in  the 
end,  whether  the  atmosphere  be  present  or  not ;  the  only  difference 
is  in  the  rapidity  of  the  process.  "Mr.  Dalton  found  that  the  tension 
or  elasticity  of  vapor,  is  always  the  same,  however  much  the  press- 
ure may  vary,  so  long  as  the  temperature  remains  constant,  and  liquid 
enough  is  present  for  preserving  the  state  of  saturation,  proper  to  the 
temperature.  If,  for  example,  in  a  vessel  containing  a  liquid,  the 
space  occupied  by  its  vapor,  should  suddenly  dilate,  the  vapor  it  con- 
tains will  dilate  also,  and  consequently  suffer  a  diminution  of  elastic 
force  ;  but  its  tension  will  be  quickly  restored,  because  the  liquid 
yields  an  additional  quantity  of  vapor,  proportional  to  the  increase 
of  space.  Again,  if  the  space  be  diminished,  the  temperature  re- 

*  For  a  description  of  Mr.  Leslie's  ^Ethrioscope,  See  Murrays'  Elements  6th  Ed- 
Vol.  I.  pa.  199. 


110  HEAT  OR  CALORIC. 

maining  constant,  the  tension  of  the  confined  vapor,  will  still  continue 
unchanged ;  because  a  quantity  of  it  will  be  condensed,  proportional 
to  the  diminution  of  space,  so  that  in  fact,  the  remaining  space  con- 
tains the  very  same  quantity  of  vapor  as  it  did  originally.  The  same 
law  holds  good,  whether  the  vapor  is  pure  or  mixed  with  any  other 
gas."* 

(j.)  Mode  of  estimating  the  force  of  vapor. — This  has  been  al- 
ready explained  under  the  head  of  vaporization.  Water  is  introdu- 
ced into  the  Torricellian  vacuum,  and  the  depression  of  the  mercury 
measures  the  force  of  the  vapor.  Vapor  being  produced  at  every 
temperature,  even  below  freezing,  a  table  was  constructed  by  Mr. 
Dalton  to  express  the  force  through  a  wide  range  of  temperature. — 
This  table,  and  the  results  since  obtained  by  Dr.  Ure,f  may  be  in- 
serted at  the  end  of  the  volume.  At  the  same  distance  from  the 
boiling  point,  the  force  of  vapor  is  the  same  in  all  fluids. 

(k.)  Effect  of  vapor  upon  gases. — It  enlarges  their  volume,  and 
that  directly,  in  proportion  to  the  temperature.  J 

Gases  are  freed  from  their  hygrometric  moisture  either  by  intense 
cold,  or  what  is  more  usual,  by  exposing  them  to  substances,  which 
powerfully  attract  moisture ;  muriate  of  lime,  which  has  been  ignit- 
ed, is  the  substance  which  is  almost  always  used,  and  it  is  very  ef- 
fectual. 

(/.)  Hygrometers. — These  depend,  generally,  upon  a  change  of 
dimensions,  in  consequence  of  absorbing  or  giving  out  moisture. — 
A  human  hair  becomes  elongated  by  imbibing  moisture,  and  returns 
to  its  former  dimensions,  when  the  moisture  is  withdrawn  ;  this  change 
is  measured  by  an  instrument,  usually  furnished  with  an  index,  and 
a  graduated  arc.  Wood,  cord,  membrane,  whalebone,  &c.  are  simi- 
larly affected. 

Cords  are  shortened  in  wet  weather  ;  this  appears  to  be  owing  to 
the  enlargement  of  their  diameter,  at  the  expense  of  their  length. 
It  is  often  observed  in  a  common  clothes  line ;  most  remarkably 
at  sea,  in  the  great  tension  of  a  ship's  rigging  during  a  rain  storm, 
and  in  the  relaxation  when  dry  weather  returns. 

The  amount  of  vapor  in  the  air,  is  estimated  with  considerable  accu- 
racy by  covering  the  bulb  of  a  thermometer  with  a  piece  of  linen 
or  silk,  and  exposing  it  to  the  air,  when  the  rapidity  and  extent  of 
the  fall  of  the  mercury  will  indicate  the  amount  of  vapor. 

Upon  this  principle,  is  constructed  a  little  instrument,^  called  the 
Rosometer.  It  is  a  thermometer,  ||  with  a  ball  of  black  glass,  the  up- 


*  Turner's  Chem.  p.  56.  t  Phil.  Trans.  1818. 

\  For  Mr.  Dalton's  formula  to  correct  this  result,  See  Turner's  Chemistry,  first 
Eng.  Ed.  pa.  58. 

§  Invented  by  Mr.  Jones  of  London,  and  Mr.  Coldstream,  of  Leith. 
]|  Filled  either  with  mercury  or  alcohol. 


HEAT  OR  CALORIC.  n 

per  part  of  which,  is  covered  with  muslin ;  a  little  ether  being  drop- 
ped upon  this  part  of  the  ball,  dew  soon  begins  to  be  deposited  on 
the  other,  and  the  temperature  at  which  this  happens,  is  called  the 
dew  point.*  Mr.  Pollock  of  Boston  constructs  this  instrument  with 
two  balls,  one  immediately  below  the  other  ;  the  upper  one  is  cov- 
ered with  muslin,  and  moistened  with  ether  and  the  dew  is  deposited 
on  the  lower  ball. 

EXPERIMENTAL    ILLUSTRATIONS     OF     THE     LAWS    OF    EVAPORATION. 

1 .  Loss  of  weight.      Water  balanced  in  scales,  loses  a  perceptible 
weight  in  a  short  time ; — with  alcohol  and  ether  the  effect  is  still 
more  remarkable. 

2.  Heat  applied  to  the  fluid  gives  a  much  quicker  result. 

3.  Camphor,  carbonate  of  ammonia,  and  other  very  volatile  solids, 
in  the  same  circumstances,  lose  weight,  although  more  tardily. 

4.  Dip  a  finger  successively  into  water,  alcohol,   and  ether,  and 
observe  that  the  sensation  of  cold,  is  stronger  and  quicker,  the  more 
evaporable  the  fluid. 

5.  Production  of  cold.      When  the  atmosphere  is  apparently  still, 
we  discover  which  tvay  the  wind  is,  by  wetting  the  finger  in  the  mouth 
and  holding  it  up  to  the  air, — it  will  feel  coldest  on  the  windward 
side,  the  evaporation  being  there  the  most  rapid,  and  consequently, 
heat  being  there  most  absorbed,  from  the  finger,  to  form  the  vapor. 

6.  Water  is  frozen  by  the  evaporation  of  ether,  j-  in  the  air  ;  this  '19 
conveniently  done,  by  placing  the  water  in  a  glass  tube,  sealed  at  one 
end  ;  it  may  be  one  third  or  one  half  of  an  inch  in  diameter,  and  the 
water  may  occupy  two  or  three  inches  in  depth  ;  a  coiled  wire  may 
be  pushed  into  the  tube  to  lift  the  ice  out,  (and  perhaps  to  aid  by  its 
conducting  power,  in  the  extrication  of  the  latent  heat ;)  if  the  water 
be  colored,  the  effect  will  be  the  more  pleasing  ;  now  let  a  capillary 
stream  of  ether,  from  a  dropping  tube  or  otherwise  fall  upon  the  tube 
containing  the  water,  which  may  be  either  naked  or  may  have  a  little 
gauze  wrapped  around  it ;  in  a  few  minutes  the  water  will  be  frozen 
solid,   and  a  momentary  pressure  of  the  tube  in  the  hand  will  thaw 
the  outside  of  the  ice,  so  that  it  may  be  withdrawn  by  the  wire. 

7.  Cold  produced  by  the  Palm  Glass. — Dr.  Hare,  from  7  to  13. 

"  Two  bulbs  are  formed,  at 
each  end  of  a  tube,  one  having 
a  perforated  projecting  beak. — 
By  warming  the  bulbs,  and 
plunging  the  orifice  of  the  beak 

*  Phil.  Trans.  1826— Edin.  Phil.  Jour.  No.  XVII.  pa.  155. 
i  This  fact  was  mentioned  on  p.  105. 


112  HEAT  OR  CALORIC. 

into  alcohol,  a  portion  of  this  fluid  enters,  as  the  air  within  contracts 
by  returning  to  its  previous  temperature.  The  liquid,  thus  introdu- 
ced, is  to  be  boiled  in  the  bulb  which  has  no  beak,  until  the  whole  cav- 
ity of  the  tube,  and  of  both  bulbs  not  occupied  by  liquid  alcohol,  is 
filled  with  its  vapor." 

"  While  in  this  situation,  the  end  of  the  beak  is  to  be  sealed,  by 
fusing  it  in  a  flame  excited  by  a  blow  pipe." 

"As  soon  as  the  instrument  becomes  cold,  the  vapor  which  had 
filled  the  space  within  it,  vacant  of  alcohol  in  the  liquid  form,  is  con- 
densed, and  a  vacuum  is  produced  ;  excepting  a  slight  portion  .of  va- 
por, which  is  always  emitted  by  liquids  when  relieved  from  atmos- 
pheric pressure." 

"The  instrument,  thus  formed,  has  been  called  a  palm  glass  ;  be- 
cause die  phenomena,  which  it  displays,  are  seen  by  holding  one  of 
the  bulbs,  in  the  palm  of  one  of  the  hands." 

"When  thus  situated,  the  bulb  in  the  hand  being  lowermost,  an 
appearance  of  ebullition  always  ensues  in  the  bulb,  exposed  to 
view,  in  consequence  of  the  liquid,  or  alcoholic  vapor,  being  pro- 
pelled into  it  from  the  other  bulb  subjected  to  the  warmth  of  the  hand." 

"  This  phenomenon  is  analogous  to  the  case  of  ebullition  in  vacuo, 
or  the  culinary  paradox  ;  but  the  motive  for  referring  to  the  experi- 
ment here,  is  to  state,  that  as  soon  as  the  last  of  the  liquid  is  forced 
from  the  bulb,  in  the  hand,  a  very  striking  sensation  of  cold,  is  expe- 
rienced by  the  operator." 

"This  cold  is  produced  by  the  increased  capacity  of  the  residual 
vapor  for  caloric,  in  consequence  of  its  attenuation." 

Remark. 

A  little  ether  dropped  on  either  of  the  balls,  immediately  produces 
a  rush  of  the  fluid  into  that  ball,  and  the  other  ball  being  then  treated 
in  a  similar  manner,  the  fluid  as  rapidly  returns.  The  appearance  of 
ebullition  in  the  palm  or  pulse  glass  is  evidently  much  increased  by 
the  fact  that  the  thin  film  of  fluid,  lining  the  upper  part  of  the  ball,  to 
which  the  hand  is  applied,  is  rapidly  converted  into  vapor,  drives  the 
fluid  before  it,  and  then  rushes  through  it ;  that  there  is  no  ebullition 
of  the  mass  of  the  fluid,  is  proved  by  the  fact,  that  if  wre  reverse  the 
position  of  the  ball,  placing  it  uppermost,  and  allow  the  fluid  .to  rest 
in  the  palm  of  the  hand  it  remains  entirely  quiet. 

8.    Cold  consequent  to  a  relaxation  of  pressure. 

"  It  is  immaterial  whether  a  diminution  of  density,  arise  from  re- 
lieving condensed  air  from  compression,  or  from  subjecting  air  of  the 
ordinary  density  to  rarefaction.  A  cloud  similar  to  that  which  has 
been  described  as  arising  in  a  receiver  partially  exhausted,  may  usu- 
ally be  observed  in  the  neck'  of  a  bottle  recently  uncorked,  in  which 
a  quantity  of  gas  has  been  evolved  in  a  state  of  condensation  by  a 
fermenting  liquor." 


HEAT  OR  CALORIC.  113 

Apparatus  for  showing  the  influ- 
ence of  Relaxed  Pressure,  on 
the  capacity  of  Mr  for  Heat, 
or  Moisture. 

"  A  glass  vessel  with  a  tubulure 
and  a  neck,  has  an  air  thermom- 
eter, fastened  air  tight,  by  means 
of  a  cork  into  the  former,  while 
a  gum  elastic  bag  is  tied  upon  the 
latter,  as  represented  in  this  fig- 
ure. Before  closing  the  bulb, 
the  inside  should  be  moistened. 
Under  these  circumstances,  if 
the  bag,  after  due  compression 
by  the  hand,  be  suddenly  releas- 
ed, a  cloud  will  appear  within 
the  bulb,  adequate  in  the  solar 
rays,  to  produce  prismatic  colors. 
At  the  same  time  the  thermome- 
ter will  show  that  the  compres- 
sion is  productive  of  warmth — 
the  relaxation  of  cold." 
"  The  tendency  in  the  atmosphere  to  cloudiness,  at  certain  el- 
evations, may  be  ascribed  to  the  rarefaction  which  air  inevitably  un- 
dergoes, in  circulating  from  the  earth's  surface  to  such  heights."* 


*  In  connexion  with  this  effect  on  the  transparency  of  the  atmosphere,  it  may  be 
interesting  to  recollect,  the  important  influence  of  barometrical  pressure  on  our 
health  and  comfort.  If  we  were  to  regard  (a  supposition  which  is  not  exactly  true, 
but  which  may  be  made  for  the  sake  of  illustration,)  the  muscular  power  of  the  heart 
and  arteries  as  a  constant  force,  propelling  the  blood  regularly  in  the  circulation ; 
then  it  is  obvious,  that  the  varying  pressure  of  the  atmosphere  must  necessarily  af- 
fect both  our  feelings  and  our  safety.  With  a  diminished  pressure,  there  must  be  a 
more  rapid  and  hurried  circulation,  and  with  it  we  might  expect  faintness  and  op- 
pression as  is  experienced  on  high  mountains.  The  oppression  and  lassitude  expe- 
rienced in  what  is  called  a  heavy  air,  (which  is  really  a  lighter  air,  our  feelings  alone 
being  heavy,)  is  probably  owing,  in  part,  to  this  cause.  At  moderate  elevations,  we 
do  not  experience  oppression,  for  there  is  generally  a  clearer  and  a  cooler  atmos- 
phere, and  our  moral  energy  is  invigorated  by  the  scenery,  and  our  physical  force 
by  the  exercise.  The  subject  is  perhaps  worthy  of  some  attention  in  selecting  situa- 
tions for  invalids,  but  many  other  causes  must  be  taken  into  view,  such  as  the  exha- 
lations, the  temperature,  &c. 

15 


114 


HEAT  OR  CALORIC. 


9.  Influence   of  pressure  on  the  escape  of  gaseous  substances  from 

combination. 

"  When  one  of  the  ingredients  of  a  Solid,  or  Liquid,  is  prone  to 
assume  the  aeriform  state,  its  extrication  will  be  more  or  less  easily 
effected,  in  proportion,  as  the  Pressure  of  the  Atmosphere  is  increas- 
ed, or  diminished." 

"  If  a  tall  cylindrical  jar,  containing  a  car- 
bonate undergoing  the  action  of  an  acid,  be 
placed  under  a  receiver,  and  the  air  with- 
drawn by  an  air  pump,  the  effervescence  will 
be  augmented.  But  if,  on  the  other  hand, 
the  same  mixture  be  placed  in  a  receiver,  in 
which  the  pressure  is  increased,  by  condensa- 
tion, the  effervescence  will  be  diminished.  In 
the  one  case,  the  effort  of  the  carbonic  acid  to 
assume  the  gaseous  state,  is  repressed  ;  in  the 
other,  it  is  facilitated.  Hence  the  necessity 
of  condensation,  in  the  process  for  manufac- 
turing mineral  water.  Beyond  an  absorption 
of  its  own  bulk  of  the  gas,  the  affinity  of  the 
water  is  inadequate  to  subdue  the  tendency  of 
the  acid  to  the  aeriform  state  ;  but  when,  by 


exterior  mechanical  pressure,  a  great  number 
of  volumes  of  the  gas  are  condensed  into  the  space  ordinarily  occu- 
pied by  one,  the  water  combines  with  as  large  a  volume  of  the  con- 
densed gas,  as  if  there  had  been  no  condensation." 

If  a  gas,  under  the  ordinary  pressure  of  the  atmosphere,  will  com- 
bine with  water  in  the  proportion  of  equal  volumes,  the  pressure  be- 
ing doubled,  the  water  will  combine  with  two  volumes  of  the  gas,  and 
if  this  last  pressure  be  doubled,  the  volume  of  gas  combined  will  be 
again  doubled ;  that  is,  it  will  be  quadrupled,  compared  with  the 
first  quantity  combined  under  the  ordinary  atmospheric  pressure,  and 
so  on.  When  thus  charged,  if  suddenly  relieved  from  all  the  extra 
pressure,  by  simply  opening  the  vessel,  as  in  drawing  soda  water, 
the  fluid  is  violently  agitated,  because  the  gas  that  was  forcibly  com- 
bined, then  resumes  its  elastic  form. 


HEAT  OR  CALORIC. 

10.   Cold  produced  by  vaporization  in  vacuo, 
by  boiling  ether. 


Water  frozen 


"  Let  a  portion  of  water,  just  adequate  to 
cover  the  bottom,  be  introduced  into  the  ves- 
sel, represented  in  the  subjoined  .drawing,  as 
suspended  within  a  receiver.  Over  the  wa- 
ter, let  a  stratum  of  ether  be  poured,  from  an 
eighth,  to  a  quarter  of  an  inch  in  depth.  If, 
under  these  circumstances,  the  receiver  be 
placed  on  the  air  pump  plate,  and  sufficiently 
exhausted,  the  ether  boils  and  the  water 
freezes." 


1 1 .  Congelation  of  water  in  an  exhausted  receiver,  by  the  aid  of 
sulphuric  acid. 

"  In  the  preceding  experiment,  water  is  frozen  by  the  rapid  ab- 
straction of  caloric,  consequent  to  the  copious  vaporization  of  ether, 
when  unrestrained  by  atmospheric  pressure.  In  vacuo,  water  un- 
dergoes a  vaporization  analogous  to  that  of  the  ether  in  the  preced- 
ing experiment ;  but  the  aqueous  vapor  evolved  in  this  case,  is  so 
rare,  that  it  cannot  act  against  valves  with  sufficient  force,  to  allow  of 
its  being  pumped  out  of  a  receiver  with  the  rapidity  requisite  to  pro- 
duce congelation.  However,  by  the  process  which  I  am  about  to 
describe,  water  may  be  frozen  by  its  own  vaporization." 


*  This  experiment  is  neatly  performed  by  placing  water  in  a  watch  glass  upon  a 
stand,  and  covering  it  with  a  thin  metallic  cup  into  which  the  ether  is  poured  :  on 
working  the  pump,  the  ether  will  boil,  and  the  water  will  freeze  ;  thug  freezing  and 
boiling  are  coincident,  and  the  boiling  is  the  cause  of  the  freezing,  and  yet  the  boil- 
ing fluid  is  as  cold  as  that  which  is  freezing. 

These  experiments  "are  more  apt  to  succeed  promptly  if  the  ether  be  good ;  it 
is  well  to  wash  it  two  or  three  times  with  water  in  a  bottle,  in  a  mode  to  be  de- 
scribed hereafter,  and  if  the  water  which  is  used  for  freezing,  has  been  just  formed 
from  melted  ice  or  snow,  it  freezes  so  much  the  quicker  as  it  has  less  sensible  heat 


no 


HEAT  OR  CALORIC. 


"  A  thin  dish,  or  pane  oi 
glass,  covered  by  a  small 
quantity  of  water,  and  situ- 
ated over  some  concentra- 
ted sulphuric  acid,  in  a 
broad  vessel,  is  placed  on 
the  air  pump  plate  within  a 
receiver,  as  represented  in 
this  engraving.  Under  these 
circumstances,  the  exhaus- 
tion of  the  receiver  causes 
the  congelation  of  the  wa- 
ter." 

12.   Wollaston's  Cryophorus. 

"  The  adjoining  figure  represents  the  Cryophorus,  or 
frost  bearer ;  an  instrument,  invented  by  the  celebrated 
Wollaston,  in  which  congelation  is  produced  in  one  cav- 
ity, by  the  rapid  condensation  of  vapor  in  another." 

"  In  form,  this  instrument  obviously  differs  but  little 
from  the  palm  glass,  already  described  (46.)     It  is  sup- 
plied by  the  same  process,  with  a  small  portion  of  water, 
instead  of  alcohol ;  so  that  there  is  nothing  included  in  it, 
unless  water,  either  liquid,  or  in  vapor." 
, ,          "  The  Cryophorus  being  thus  made,  if  all  the  water  be 
r    j  allowed  to  run  into  the  bulb  near  the  bent  part  of  the  tube, 
^— "*   and  the  other  bulb  be  immersed  in  a  freezing  mixture, 
the  water  will  freeze  in  a  few  minutes." 

"  So  long  as  no  condensation  is  effected,  of  the  thin  aqueous  vapor, 
which  occupies  the  cavity  of  the  instrument,  that  vapor  prevents,  by 
its  repulsion,  the  production  of  more  vapor :  but  when,  by  means  of 
cold,  the  vapor  is  condensed  in  one  bulb,  its  evolution  in  the  other, 
containing  the  water,  being  unimpeded,  proceeds  rapidly.  Mean- 
while the  water  becomes  colder,  and  finally  freezes,  from  losing  the 
caloric  which  the  vaporization  requires." 

"  According  to  Wollaston,  one  grain  of  water,  converted  into  va- 
por, holds  as  much  caloric  as  would,  by  its  abstraction,  reduce  thirty 
one  grains  from  60°  Fahr.  to  the  freezing  point ;  and  the  caloric  re- 
quisite to  vaporize  four  grains  more,  if  abstracted  from  the  residual 
twenty  seven  grains,  would  convert  them  into  ice. 


HEAT  OR  CALORIC.  H7 

13.  Large  Cryophorus. 


"  This  figure  represents  a  very  large  Cryophorus,  the  blowing  of 
which  1  superintended  ;  and  by  means  of  which  I  have  successfully 
repeated  Wollaston's  experiment." 

"  This  instrument  is  about  four  feet  long  ;  and  its  bulbs  are  about 
five  inches  in  diameter." 

VI.  IGNITION  OR  INCANDESCENCE. 

(a.)  Bodies  become  luminous  in  consequence  of  the  accumulation 
of  heat  in  them.* — In  common  language,  this  is  expressed  by  saying 
that  bodies  become  red  hot,  as  a  bar  of  iron  does  among  burning 
coals. 

Some  bodies  melt  during  their  ignition  ;  this  is  the  fact  with  stones 
and  most  metals,  and  the  melted  stone  or  metal  is  as  truly  red  hot  as 
the  bar  of  ignited  iron.  Some  bodies  evaporate  during  ignition  ; 
such  are  antimony,  bismuth,  lead  and  tin ;  some  evaporate  before  ig- 
nition, as  water  and  most  fluids,  not  excepting  the  most  fixed  fluids, 
as  quicksilver,  and  sulphuric  acid,  and  dense  oils ;  the  latter  are  de- 
composed before  ignition. 

Gases  do  not  become  luminous  at  any  temperature,  although  they 
may  cause  solid  bodies,  as  gold,  &tc.  immersed  in  them,  to  become 
luminous,  the  reason  appears  to  be,  that  there  is  not  matter  enough 
in  any  one  point  to  project  the  light  to  the  eye,  although  from  their 
communicating  ignition  to  solid  bodies,  it  is  certain  that  they  have 
the  requisite  heat. 

Mr.  Perkins'  high  steam,  it  would  appear,  is  capable  of  igniting 
other  bodies,  (as  already  stated  under  steam  and  vapor ;)  it  kindled 
tow  and  ropes,  and  it  even  ignited  the  bored  orifice  in  the  generator 
from  which  it  was  issuing ;  still  it  does  not  appear  certain  that  it  was 
itself  luminous,  nor  is  it  certain  that  it  was  not,  because  we  cannot 
inspect  the  steam  formed  in  opake  vessels,  like  those  of  metal,  and 
when  the  steam  issues  into  the  air,  it  is  no  longer  high  steam ;  just 
at  the  orifice  of  emission,  it  is  elastic  and  invisible,  but  a  little  way 
from  it,  it  forms  a  cloud  of  mist. 

(b.)  Bodies  become  luminous  by  friction. — Glass,  or  agate,  or 
quartz,  held  against  a  revolving  gritstone  or  grindstone,  become  hot 
and  luminous.  Metals  are  affected  in  the  same  manner.  The  parts 
of  gun  locks  and  other  pieces  of  steel  emit  sparks  when  held  firmly 
against  grindstones  or  revolving  wheels,  covered  with  emery  powder 

*  They  are  not  supposed  to  undergo  decomposition  during  their  ignition. 


118  HEAT  OR  CALORIC, 

spread  upon  oiled  leather  straps,  which  serve  as  bands  to  the 
wheels.* 

(c.)  Jill  bodies  begin  to  shine  by  heat  at  the  same  temperature. — 
This  fact  was  first  discovered  by  Sir  Isaac  Newton,  and  has  been 
confirmed  by  others. 

In  genera],  redness,  that  is  the  emission  of  red  rays,  commences  at 
about  800°  of  Fahr.  and  is  fully  established  in  broad  day  light  at 
1000°  in  the  direct  sun's  light,  perhaps  about  1100°,  or  possibly 
1200°.  The  appearance  is  of  course  much  influenced  by  the  quan- 
tity of  the  surrounding  light.  A  body  might  be  luminous  in  the  dark, 
that  would  not  be  at  all  so  in  the  light. 

There  are  many  cases  of  phosphorescence  or  emission  of  light 
which  are  not  attended  by  any  considerable  increase  of  heat ;  these 
have  been  already  mentioned  under  the  head  of  light. 

(d.)  A  white  heat  is  only  a  greater  degree  of  ignition. — White 
light,  that  is,  light  containing  a  due  proportion  of  all  the  colored  rays, 
is  emitted  when  the  accumulation  of  heat  is  the  greatest ;  a  welding 
heat  of  iron  is  a  white  heat.  The  artists  have  many  terms  to  de- 
note the  various  degrees  of  heat  connected  with  their  processes ; 
thus,  they  speak  of  a  cherry  red,  a  worm  red,  &c.  and  of  a  white 
heat,  a  blue  white,  a  red  white,  &tc.  and  there  are  many  degrees  of 
heat  between,  commencing  with  the  feeblest  redness  visible  only  in 
the  dark,  and  ending  with  a  full  white  light,  distinctly  visible  even  in 
the  blaze  of  the  meridian  sun.f 

(e.)  Ignition  affords  one  of  the  strongest  arguments  for  the  iden- 
tity of  light  and  heat. — If  they  are  different  substances  or  powers, 
then  the  heat  when  accumulated  to  a  certain  degree,  expels  the  light, 
previously  lodged  in  the  body ;  or,  it  may  be  said,  that  as  most  cases 
of  ignition  are  produced  by  burning  bodies,  the  light  from  the  fire 
enters  the  body  along  with  the  heat,  and  thus  obtains  a  transit ;  or,  if 
heat  and  light  are  merely  modifications  of  each  other,  then  it  may 
be  supposed  that  at  a  certain  temperature  heat  becomes  light,  or  pos- 
sibly a  certain  accumulation  or  intensity  of  radiant  heat  affects  the 
optic  nerves  so  as  to  produce  the  sensation  of  vision.  J 

*  This  is  beautifully  seen  at  the  gun  manufactory,  at  Whitneyville,  near  New 
Haven ;  the  sparks  fly  off  in  innumerable  tangents,  and  the  hand,  unless  brought 
very  near,  may  be  held  in  the  fiery  stream  without  inconvenience  ;  this  is  doubtless 
owing  to  the  strong  current  of  air  which  the  revolution  of  the  wheels  produce.  It 
is  curious  that  while  coarse  emery  is  used,  gunpowder  is  inflamed  by  the  sparks  at 
any  distance  to  which  they  extend  ;  but,  when  very  fine  emery  is  used,  coarse  gun- 
powder is  not  kindled,  but  if  finely  pulverized,  it  then  flashes  with  the  minutest 
sparks. — (Communicated  by  Mr.  Eli  Blake  of  Whitneyville.) 

t  Although  it  is  called  a  white  heat,  there  are  more  red  rays  than  are  contained 
in  the  sun  beams. 

±  The  very  mild  heat  which  causes  the  emission  of  light  from  some  bodies,  e.  g. 
fluor  spar,  countenances  the  opinion  that  light  is  lodged  in  them ;  and  light  may  be 
imparted  to  some  bodies  to  such  a  degree,  that  they  become  partially  transparent 
without  producing,  upon  them,  the  effects  of  ignition  ;  thus,  eggs,  the  human  fingers, 
and  other  bodies  are  illuminated,  through  and  through,  by  an  electrical  discharge. 


HEAT  OR  CALORIC.  H9 

If  we  suppose  that  the  entrance  of  heat  continues  to  expel  light 
from  a  body  for  an  indefinite  time,  this  difficulty  is  perhaps  removed 
by  adverting  to  the  fact,  already  suggested,  that  at  the  temperature 
of  ignition,  the  light  enters  the  body  along  with  the  heat,  and  that  both 
bodies  thus  find  a  transit  through  it.  This  however  does  not  ac- 
count for  the  indefinite  ignition  produced  by  friction ;  even  allowing 
that  it  is  indefinite,  which  has  not  yet  been  proved,  there  is  no  great- 
er difficulty  than  attends  the  indefinite  emission  of  heat  under  the 
same  circumstances. 

Perhaps  it  would  not  be  useful,  in  a  concise  text  book,  to  intro- 
duce the  speculations  of  the  learned  and  able  philosophers  who  would 
make  heat,  and  perhaps  light,  to  depend  upon  the  internal  motions 
of  the  particles  of  bodies  ;  one  kind  of  effect  depending  upon  sup- 
posed vibratory,  or  expansive,  or  retrocessive,  and  another  upon  gy- 
ratory motions  of  uncognizable  particles.*  We  might  quote  the 
great  names  of  Newton,  Boyle,  Hooke,  Rumford,  Davy,  Leslie, 
and  others.  The  question  can  perhaps  never  be  decided  ;  but  in  dis- 
cussing the  nature  of  light  and  heat,  the  statements  of  facts  and  the 
reasonings  can  be  exhibited  most  conveniently  upon  the  supposition 
that  these  agents  are  material,  and  that  they  are  different  from  each 
other.  This  course  may  therefore  be  pursued  provisionally,  until 
other  views  shall  be  conclusively  established,  f 

VII.  CAPACITY;);  FOR  HEAT,  AND  SPECIFIC  HEAT. 

(a.)  The  capacity  of  a  body  for  heat,  is  its  power  of  containing  a 
given  quantity  of  heat  at  a  given  temperature. $ — The  comparative 
estimate  between  different  bodies  is  usually  made,  by  taking  them 
hi  equal  weights ;  but  it  may  be  made  also  upon  bodies  in  equal 
volumes ;  the  numerical  results  will  of  course  be  different,  but  are 
capable  of  being  intelligibly  compared. 

(6.)  The  specific  heat  of  a  body,  is  the  particular  quantity  of  that 
power  which  it  contains  at  a  given  temperature. 

*  See  Davy's  Chemistry. 

t  See  Dr.  Hare's  paper  on  the  materiality  of  heat,  Am.  Jour.  Vol.  IV.  p.  142, 
and  the  ingenious  discussions  between  him  and  Professor  Olmsted,  in  the  same  Jour- 
nal, Yols.  XI,  XII,  XIII.  Dr.  Hare  has  shewn  that  the  phenomena  of  heat  are 
inconsistent  with  the  opinion  that  they  depend  upon  corpuscular  motion.  There 
seems  then  to  be  no  other  alternative  than  that  there  must  be  a  material  cause  of 
heat,  although  that  cause  is  too  subtle  to  be  recognized  by  us  in  any  other  way  than 
by  its  effects. 

t  The  term  is  evidently  figurative,  and  alludes  to  the  capacity  of  a  containing 
vessel.  The  use  of  the  word,  in  relation  to  heat,  implies  merely  a  power,  without 
deciding  on  the  mode. 

§  For  a  description  of  that  elegant  intrument,  the  Calorimeter  of  Lavoisier,  see 
his  elements,  and  most  of  the  larger  chemical  works.  The  quantity  of  water  ob- 
tained by  the  fusion  of  ice,  during  certain  changes  in  bodies  surrounded  by  that 
substance,  was  made  the  criterion  of  the  quantity  of  heat ;  but  there  were  some, 
perhaps  inherent,  sources  of  error,  and  the  instrument  is  now  very  little,  if  at  all 
used. 


120  HEAT  OR  CALORIC. 

The  experiments  are  commonly  made  by  comparing  fluids*  or  com- 
minuted solids,  after  they  have  been  mingled  at  different  tempera- 
tures. That  body  which,  in  a  given  short  time,  has  lost  the  greatest 
number  of  degrees,  has  the  smallest  capacity,  and  the  smallest  spe- 
cific heat,  and  vice  versa. 

The  resulting  temperature  is  always  nearest  to  that  body,  whose 
capacity  or  specific  heat  is  the  greatest,  and  therefore  the  greater  the 
capacity  the  less  the  changes  of  temperature.  Boerhaave  first  dis- 
covered this  remarkable  fact,  with  respect  to  quicksilver,  and  water, 
but  Dr.  Black  first  established  the  law  ;  many  other  able  men  have 
investigated  it,  among  whom  are  Wilcke,  Irvine,  Crawford,  Lavoisier, 
Berard,  and  Delaroche,  Petit,  and  Dulong,  Clement  and  Des- 
ormes,  &c. 

(c.)  Different  bodies,  whether  taken  in  equal  weights,  or  volumes., 
contain  different  quantities  of  heat  or  caloric. 

This  could  never  have  been  known  by  reasoning  a  priori;  the 
conclusions  are  founded  entirely  upon  experiment. 

(d.)  Different  bodies  exposed  to  the  same  heating  or  cooling  cause, 
undergo  different  changes  of  temperature,  in  equal  short  times,  and 
the  capacities  are  inversely  as  the  change  of  temperature.  Thus  fifty 
spheres,  or  cubes,  equal  either  in  weight  or  diameter,  of  as  many  dif- 
ferent kinds  of  matter,  if  plunged  into  boiling  water,  and  examined  after 
an  interval  of  five  minutes,  would  be  found  very  differently  heated  ;  or, 
if  already  arrived  at  the  temperature  of  212°,  if  they  were  exposed 
to  a  freezing  air,  and  examined  as  above,  they  would  be  found  very 
unequally  cooled,  although  in  the  end,  they  would  in  both  cases  ac- 
quire a  common  temperature. 

(e.)  In  homogeneous  bodies,  mingled  at  different  temperatures,  the 
resulting  temperature  is  always  the  arithmetical  mean. — A  pint  of 
water  at  100°,  and  a  pint  at  200°,  would  on  being  mingled,  give 
150°  as  the  resulting  temperature,  and  the  same  would  be  true  of 
any  other  fluids,  or  minutely  divided  solids. 

(/.)  In  heterogenous  bodies,  the  resulting  temperature  is  never  the 
mean. — The  capacity  of  water  is  23  that  of  mercury  1,  for  the 
changes  which  they  undergo,  when  mingled  at  different  temperatures, 
and  in  equal  weights  or  volumes,  are  inversely  as  the  changes  the) 
suffer. 

One  pint  of  mercury  at  100°  Fahr.+one  pint  of  water  at  40°,= 
not  70°,  the  arithmetical  mean,  but  only  60°  ;  the  metal  loses  40°, 
which  raises  the  water  only  20°  ;  hence,  in  equal  volumes,  water  has 
the  greater  capacity.  If  the  pint  of  water  be  100°,  and  the  mercury 
at  40°,  the  temperature  will  be  about  80°,  because  the  water  con- 
tains more  heat  than  is  necessary  to  raise  the  mercury  to  the  mean. 

*  Always  taking  it  for  granted  that  they  do  not  act  chemically  on  each  other. 


HEAT  OR  CALORIC.  121 

Water  1  in  volume,  and  mercury  2,= always  the  arithmetical  mean ; 
e.  g.  703,  if  the  extremes  be  100°  and  40°;  hence,  in  equal  vol- 
umes, water  has  twice  the  capacity  of  quicksilver. 

In  equal  weights,  one  pound  of  water  at  100°,-f-one  pound  of  mer- 
cury at  40°-~97j;  therefore  the  2|  lost  by  the  water  have  raised 
the  mercury  57  J,  which  is  in  the  proportion  of  1  :  23,  viz,  water  has 
twenty  three  times  the  specific  heat  that  is  contained  in  an  equal 
weight  of  mercury,  and  its  capacity  is  in  the  same  proportion.* 

(g.)  Formula. — 1 .  By  weight. — If  the  weight  be  multiplied  into  the 
change  of  temperature,  the  capacity  will  be  inversely  as  the  change, 
that  is,  the  greater  the  change,  the  less  the  capacity,  and  vice  versa. 
2.  By  volume  ;  the  capacity  found  as  above,  X  into  the  sp.  gr.  =  the 
capacity  by  volume. f 

(h.)  Comparing  classes  of  bodies,  the  capacities  for  heat  are,  in 
general,  inversely  as  their  density. — Solids  have  less  capacity  than 
fluids — fluids  less  than  gases,  and  vice  versa. 

When  the  capacity  is  enlarged,  heat  is  absorbed,  and  when  dimin- 
ished, it  is  given  out. 

ft;)  The  sudden  expansion  of  air  always  produces  cold. — "This 
striking  occurrence  takes  place  on  a  vast  scale  at  the  fountain  of  Hiero ; 
at  the  mines  of  Chemnitz, 'in  Hungary.  A  part  of  the  machinery  for 
working  these  mines,  is  a  perpendicular  column  of  water,  two  hun- 
dred and  sixty  feet  high,  which  presses  on  a  quantity  of  air  enclosed 
in  a  tight  reservoir.  The  air  is  consequently  condensed  to  an  enor- 
mous degree  by  this  height  of  water,  which  is  equal  to  eight  or  nine 
atmospheres,  and  when  a  pipe,  communicating  with  this  reservoir  of 
condensed  air,  is  suddenly  opened,  it  rushes  out  with  extreme  ve- 
locity, instantly  expands,  and  in  so  doing  absorbs  so  much  caloric,  as 
to  precipitate  the  moisture  it  contains  in  a  shower  of  very  white  com- 
pact snow,  or  rather  hail,  which  may  be  readily  gathered  on  a  hat, 
held  in  the  blast.  The  force  of  this  is  so  great,  that  the  workman 
who  holds  the  hat  is  obliged  to  lean  his  back  against  the  wall  to  re- 
tain it  in  its  position.  If  the  cock  of  the  pipe  is  only  partly  opened, 
the  snow  is  still  more  compact."{ 

By  condensing  aeriform  bodies  into  a  small  space,  cooling  them 
by  freezing  mixtures,  and  liberating  them  suddenly,  great  cold  is 
produced  by  the  rarefaction. 

We  have  found  occasion  more  than  once  to  remark  that  similar 
effects  probably  happen  in  the  higher  regions  of  the  atmosphere,  from 
the  sudden  liberation  of  the  ascending  currents  of  rarefied  air  from 
pressure,  and  from  their  mixture  with  colder  currents. 

(j.)  Great  and  sudden  increase  of  pressure  upon  common  air,  evolves 
so  much  heat  as  to  ignite  very  combustible  bodies. — This  was  exhibit- 

*  Henry's  Chemistry.  The  author  quotes  Dalton ;  the  numbers  usually  stated 
are  as  1  to  28.  f  Murray.  1  Aikin,  I,  213. 

10 


122  HEAT  OR  CALORIC. 

ed  by  a  brass  syringe,  furnished  at  one  end  with  a  little  chamber, 
containing  tinder,  agaric,  or  other  combustible,  which  is  heated  by 
the  compression  produced  by  the  quick  stroke  of  the  piston,  so  that 
the  combustible,  on  being  suddenly  brought  to  the  air,  by  the  turn- 
ing of  a  key,  took  fire.  More  recently,  the  combustible  is  contained 
in  the  piston  itself,  which,  after  the  stroke,  is  quickly  withdrawn  from 
the  tube.  The  instrument  is  now  made  of  glass,  which  enables  one 
to  see  the  flash. 

(k.)  Changes  of  capacity  for  caloric  have  an  intimate  connexion 
with  the  regulation  of  natural  and  artificial  temperature. — The  me- 
dium heat*  of  the  globe  is  usually  placed  at  about  50°  of  Fahr.  and 
is  found,  as  has  been  heretofore  believed,  at  about  1000  feet  below  the 
surface  of  the  ground. 

Medium  heat  of  the  atmosphere  at  New  Haven,  about  50°. f 
"  "     "  the  Torrid  zone,  70°  to  80°. 

"  "     "  moderate  climates,  50°  to  52°. 

"  "     "  near  the  polar  regions,  about  36°. 

The  extremes  of  the  globe  are  from  about— 50°  sometimes— 70® 
to  100°,  105°,  110°;  and  even  120°,  or  perhaps  in  some  situa- 
tions, still  more. 

The  extremes  of  artificial  temperature*  are  much  greater,  from 
—  91°,  to  35127°,  (Henry.)  which  is  the  highest  estimated  heat,  but 
we  know  that  it  is  not  the  highest  heat  that  has  actually  been  produc- 
ed. We  have  no  measure  for  it,  and  probably  can  never  have  any 
other  than  the  effects  which  such  heats  produce  in  fusion,  &c.  The 
real  zero  has  never  been  discovered. { 

( /.)  Freezing  mixtures  act  by  enlargement  of  capacity. — A  solid, 
as  already  observed,  is  always  one  ingredient  in  these  compositions ; 
it  becomes  fluid  by  uniting,  chemically,  with  some  other  agent,  and 
thus  absorbs  heat  and  produces  cold.  Salts  and  acids,  as  Glauber's, 
eight  ounces,  and  muriatic  acid,  five  ounces,  are  most  commonly  em- 
ployed, and  sink  the  thermometer  from  50°  to  0.  When  both  in- 
gredients are  solid,  the  mixture  is  still  more  powerful,  as  in  the  case 
of  muriate  of  lime  and  snow ;  and  of  muriate  of  soda  and  snow  ;  by 
the  former,  mercury  is  frozen.  Snow,  or  pounded  ice,  two  parts,  and 
common  salt,  one  part,  depress  the  thermometer  from  50°  to— 5°.§ 

The  mere  solution  of  a  salt  in  water  produces  cold.  Nitre,  in 
large  quantities,  added  to  water,  sinks  the  thermometer  17° ;  ni- 

-  Should  the  views  of  Prof.  Cordier,  as  to  the  increasing  heat  of  the  interior  of 
the  earth,  be  established,  the  result  stated  in  the  text  cannot  be  correct ;  but  it  will 
require  numerous  and  often  repeated  observations,  extending  to  many  countries, 
and  through  many  years,  to  establish  a  conclusion  so  extraordinary  — See  Am.  Jour. 
Vol.  15.  p.  109. 

t  Pres.  Day,  in  Trans,  of  Conn.  Acad. 

t  We  think  it  useless  to  reiterate  the  fruitless  discussions  on  this  subject ;  they 
may  be  found  in  all  the  larger  chemical  works.  It  is  evident  that  no  reliance  can 
be  placed  upon  the  results,  widely  discordant  as  they  are. 

§  For  a  more  copious  table  of  freezing  mixtures,  see  p.  136. 


HEAT  OR  CALORIC.  12.; 

trate  of  ammonia,  28°  ;  muriate  of  lime  three  parts,  and  water  two, 
37° ;  muriate  of  ammonia,  and  nitre  in  powder,  with  from  five  to 
eight  parts  of  water,  from  50°  to—  11°  ;  and  the  salts,  recovered  by 
evaporation,  answer  as  well  as  before. 

Diluted  acids  with  salts,  are  more  powerful  than  water  only.  Sul- 
phate of  soda,  with  sulphuric  acid,  diluted  with  as  much  water,  re- 
duces the  temperature  from  50°  to  5°,  and  with  diluted  nitric  acid, 
from  51°  to  1°.  With  mixed  salts  the  cold  is  still  greater.  Phos- 
phate of  soda,  nitrate  of  ammonia,  and  diluted  nitric  acid,  reduce  the 
thermometer  from  50°  to  —21°,  and  mercury  has  been  frozen  by  a 
mixture  of  nitrous  acid,  sulphate  of  soda,  and  nitrate  of  ammonia.* 
By  these,  or  similar  means,  all  fluids  have  been  frozen,  except  al- 
cohol, and  several  of  the  gases  have,  by  the  aid  of  strong  pressure, 
been  condensed  into  fluids. 

The  salts  should  be  previously  well  crystallized,  and  should  retain 
their  full  proportion  of  water  ;  they  should  be  well  pulverized  ;  they 
should  be  mixed  in  vessels  which  are  bad  conductors  of  heat ; 
the  access  of  the  external  air  should,  as  much  as  possible  be  cut  ofF, 
and  the  materials  may  be  previously  cooled  by  being  placed  sepa- 
rately in  other  freezing  mixtures,  taking  care  that  they  be  not  cooled 
below  that  degree  at  which  the  materials  act  on  each  other.f 

(m.)  Many  heat-producing ,  or  calorific  mixtures,  act  by  diminu- 
tion of  capacity.-. — Sulphuric  acid  and  water  combine  with  increase 
of  specific  gravity,  and  diminution  of  specific  heat,  and  therefore 
with  increase  of  sensible  heat. 

Many  other  acids,  e.  g.  the  nitric,  muriatic,  fluoric,  &tc.  act  in  the 
same  way ;  even  alcohol  and  water,  in  considerable  quantities,  grow- 
sensibly  warm  by  being  mixed.  The  heat  evolved  in  those  cases 
in  which  the  products  of  the  chemical  action  are  chiefly  gaseous,  does 
not  appear  to  be  well  accounted  for  in  this  way.  Nitric  acid  and  oils, 
gunpowder  and  fulminating  compositions  generally,  and  mixtures  of 
the  chlorates  with  the  combustibles,  result  in  the  conversion,  more  or 
less,  of  solids  into  aerial  matter,  and  cold  should  therefore  be  genera- 
ted, instead  of  heat,  which  is  always  evolved  in  great  quantities. 

Dr.  Turner  sums  up  our  knowledge  of  specific  heat  under  the  fol- 
lowing heads. 

1.  "  Every  substance   has  a  specific    caloric  peculiar  to   itself, 
whence  it  follows  that  a  change  of  composition  will  be  attended  by  a 
change  of  capacity  for  caloric." 

2.  "A  change  of  form,  the  composition  remaining  the  same,  is 
likewise  attended  with  a  change  of  capacity.     It  is  increased  when  a 
solid  liquifies,  and  diminished  when  a  fluid  passes  into  a  solid." 

3.  "  It  is  certain  that  the  specific  caloric  of  all  gases  increases  as 
their  density  diminishes,  and  vice  versa. 

*  Graham.  *  Murray. 


124 


HEAT  OR  CALORIC. 


Mr.  Dalton  contends  that  this  law  prevails  also  in  solids  and  fluids,* 
and  Petit  and  Dulong  have  proved  it  with  respect  to  several  solid?. 
The  specific  heat  of  Iron  was  found  to  be 

Centigrade.  Specific  heat. 

From      0     to      100°  -                             0.1098 

"       .0      «     200°     -  -    0.1150 

"         o      "     300°  0.1218 

«         0      "     350°     -  -    0.1255 
And  so  of  other  bodies. 


Spec,  heats-,  from 
0  to  100  cent. 

0.0330 

-  0.0927 
0.0507 

-  0.0557 
0.0049 

-  0.0355 
0.1770 


Spec  heat  from 
0  to  30"  iif 
0.0350 

-  0.1015 
0.0549 

-  0.0611 
0.1013 

-  0.0355 
0.1900 


Mercury, 

Zinc, 

Antimony, 

Silver, 

Copper, 

Platinum,  - 

Glass,     - 

4.  "  Petit  and  Dulong  have  rendered  it  probable  that  the  atoms  of 
all  simple  substances  have  the  same  specific  caloric. "f 

This  is  illustrated  by  a  pretty  copious  table,   for  which  see  the 
Ann.  de  Chimie  et  de  Physique,  Vol.  10. 

5.  "  A  change  of  capacity  for  Caloric  always  occasions  a  change 
of  temperature.     An  increase  of  the  former  is  attended  by  a  diminu- 
tion of  the  latter  ;  and  a  decrease  of  the  former  is  attended  by  an  in- 
crease of  the  latter." 


The  specific  heat  of  the 
cording  to  Dela  Roche  and 
follows. 

Under  equal 
volumes. 

Atmospheric  Air,  1.0000 

Hydrogen  Gas,  0.9033 

Oxygen  Gas,  0.9765 

Nitrogen  Gas,  1.0000 

Nitrous  Oxide,  3.3503 

OlefiantGas,  1.5530 

Carbonic  Oxide,  1.0340 

Carbonic  Acid,  1.2583 


'ases  is  an  interesting 
erard,  several  of  them 


Under  equal 

weights. 
1.0000     - 
1.2340 
0.8848     - 
1.0318 
0.8878     - 
1.5763 
1.0805     - 
0.8280 


problem.     Ac- 
stand  related  as 

Specific 
gravities. 

-  1.0000 
0.0732 

-  1.1036 
0.9691 

-  1.5209 
0.9885 

-  0.9569 
1.5196 


*  Chera.  Phil,  part  1.  p.  50. 

t  By  comparing  the  equivalents  of  twelve  principal  metals,  and  of  sulphur,  as 
given  by  Petit  and  Dulong,  and  by  Dr.  Turner,  in  his  Chemistry,  it  has  been  found 
thai  the  product  arising  from  the  multiplication  of  those  equivalents  into  the  spe- 
cific heat  of  the  bodies,  gives  results  so  widely  differing  from  uniformity,  as  "  would 
Beem  to  take  all  plausibility  froTj  the  hypothesis  that  the  atoms  of  simple  bodies  har.'* 
the  same  specific  heat." — Bache,  in  Jour.  Jlcad.  Nat.  Sci.  Phil.  Jan.  1829. 


HEAT  OR  CALORIC. 


125 


Water   being  unity,  the 

specific 

Specific  heat  of  metals,  accord- 

heats of  the  gases  are  as  fol- 

ing to  Petit  and 

Dulong. 

lows. 

Bismuth,     - 

-     0.0288 

Water,  -     -     -     - 

1.0000 

Lead, 

0.0298 

Atmospheric  Air, 

0.2669 

Gold,           -       - 

-     0.0298 

Hydrogen  Gas, 

3.2936 

Platinum, 

0.0314 

Carbonic  Acid, 

0.2210 

Tin,     -       -       - 

-     0.0514 

Oxygen  Gas,    -     - 

0.2361 

Silver,     -       - 

0.0557 

Azote,     -     -     -     - 

0.2754 

Zinc, 

-     0.0927 

Protoxide  of  Azote, 

0.2369 

Tellurium, 

0.0912 

Olefiant  Gas,     -     - 

0.4207 

Copper, 

-     0.0949 

Oxide  of  Carbon, 

0.2884 

Nickel,    -       - 

0.1035 

Steam,   -     -     -     - 

0.8470 

Iron,    - 

-     0.1100 

Cobalt,    -       - 

0.1498 

Sulphur, 

-     0.1880 

It  is  worthy  of  observation  that  all  the  gases,  excepting  hydrogen, 
have,  according  to  Petit  and  Dulong,  less  specific  heat  than  water ; 
this  is  the  fact  even  with  steam.  It  would  seem  that  they  had  some 
doubts  as  to  the  correctness  of  this  result. 

Apparatus  for  illustrating  capacities  for  heat. — Dr.  Hare. 

"  Let  the  vessels 
A,B,and  C,  be  sup- 
plied with  water 
thro  ugh  the  tube  T. 
which  commmuni- 
cates  with  each  of 
them,  by  a  hori- 
zontal channel  in 
the  wooden  block. 
The  water  will  rise 
to  the  same  level  in  all.'  Of  course  the  resistance  made  by  the  wa- 
ter, in  each  vessel,  to  the  entrance  of  more  of  this  liquid  will  be  the 
same,  and  will  be  measured  by  the  height  of  the  column  of  water  in 
the  tube  T.  Hence  if  the  height  of  this  column  were  made  the  in- 
dex of  the  quantity  received  by  each  vessel,  it  would  lead  to  the  im- 
pression that  they  had  all  received  the  same  quantity.  But  it  must 
be  obvious,  that  the  quantities  severally  received,  will  be  as  different 
as  are  their  horizontal  areas.  Of  course  we  must 'not  assume  the 
resistance  exerted  by  the  water  within  the  vessels  against  a  further 
accession  of  water  from  the  tube,  as  any  evidence  of  an  equality  in  the 
portions  previously  received  by  them." 


126  HEAT  OR  CALORIC. 

VIII.  COMBUSTION. 

(a.)  In  common  language  it  means  the  same  as  burning  ;  that  is, 
in  most  cases,  the  apparent  consumption*  of  a  body,  and  an  entire 
change  in  its  properties,  with  the  emission  of  heat  and  light. 

(b.)  In  what  was  catted  the  new  or  French  theory,  combustion  was 
synonymous  with  a  combination  of  oxygen  with  a  combustible  body, 
attended  by  augmentation  of  its  weight,  and  change  of  its  nature,  heat 
and  light  being  at  the  same  time  emitted. — Now,  Chlorine  is  added  as 
another  agent  possessed  of  similar  powers  with  oxygen ;  also,  by 
some,  Iodine  ;  and  many  even  regard  every  case  of  intense  chemical 
action,  with  the  emission  of  heat  and  light,  as  combustion. 

"  Whenever  the  chemical  forces  that  determine  either  combina- 
tion or  decomposition,  are  energetically  exercised,  the  phenomena  of 
combustion,  or  incandescence,  with  a  change  of  properties,  are  dis- 
played."! 

In  general  we  shall  use  the  word  combustion  in  its  common  and 
more  restricted  sense,  taking  due  notice,  however,  of  the  other  cases 
as  we  come  to  them. 

(c.)  It  would  be  premature  to  consider  combustion  fully  at  pre- 
sent ;  for  its  theory  and  phenomena  are  best  developed  progressively 
as  we  proceed. 

We  mention  combustion  in  this  place  merely  to  complete  our  list 
of  the  effects  of  heat;  for,  as  commonly  seen,  it  sustains  a  very  close 
connexion  with  heat,  since  an  exalted  temperature  is  usually  neces- 
sary to  its  existence.  Heat  is,  however,  often  the  consequence,  as 
well  as  the  cause  of  combustion. 

(d.)  Phlogiston  is  a  name  formerly  given  to  a  principle  of  com- 
bustion, supposed  to  reside  in  all  inflammable  bodies  ;  dissipated,  as 
was  imagined,  in  the  form  of  heat  and  light,  during  combustion ;  the 
body  being  thereby  rendered  uninflammable,  and  its  inflammability 
being  again  restored  by  recombining  with  phlogiston,  as  when  red 
lead  is  heated  with  charcoal  which  causes  the  incombustible  metallic 
oxide  to  become  again  combustible  in  the  form  of  metallic  lead. 

This  theoryf  is  now  obselete,  but  in  its  time,  it  rendered  important, 
service  to  the  science  of  Chemistry,  and  was  in  vogue  for  a  century. 
Phlogiston  comes  very  near  to  the  modern  idea  of  combined  and  free 
caloric.  If  we  substitute  a  combination  of  oxygen  for  the  extrication 
of  phlogiston,  and  the  extrication  of  oxygen  for  the  combination  of 
phlogiston,  we  translate,  very  nearly,  all  the  common  cases  of  com- 
bustion, from  one  theory  into  the  other. 


*  Sometimes  the  body  remains,  but  in  an  incombustible  state. 

i  lire's  Chem.  Die.        £  Invented  by  Becher,  and  more  fully  illustrated  by  StaML 


SOURCES  OP  HEAT  AND  COLD.  127 

APPENDIX  TO  CALORIC. 
SEC.  III.     SOURCES  OF  HEAT  AND  COLD. 

I.  SOURCES  OF  HEAT  ;  most  of  which  are  also  sources  of  light. 

(a.)   The  sun. 
b.)    Combustion. 
)    Chemical  action  without  combustion. 

?    Electricity  and  Galvanism. 
Condensation  of  aeriform  bodies  by  pressure. 
)   Condensation   of  solids,    by   mechanical   action,   including 
friction  and  percussion, 
(g.)   Vital  action. 

(a.)  The  solar  rays. — The  intensity  of  the  solar  heat  being  in  pro- 
portion to  the  rays  that  can  be  collected  upon  a  given  spot,  there  ap- 
pears to  be  no  other  limit  to  our  power  of  generating  heat  in  this 
manner,  than  what  is  found  in  the  size  of  our  instruments,  and  the 
difficulty  of  using  them,  for  it  has  been  long  known,  that  the  effect  is 
much  increased  by  lenses  and  mirrors.* 

This  is  especially  true  if  the  focus  he  received  on  a  black  and 
rough  surface,  e.  g.  on  charred  cork  lining  a  box,  and  covered  by 
glass ;  thus  a  heat  of  221°,  was  produced  while  the  air  was  only  75°. 
— Saussure. — In  another  case,  the  heat  generated  by  similar  meanSj 
was  from  230°  to  237°,  while  a  bright  fire  gave,  at  the  same  time, 
212°.— Black,  Thomson. 

Dr.  Hare  remarks,  that  previously  to  the  discovery  of  the  heat  ex- 
cited by  oxygen,  by  the  compound  blowpipe,  or  by  the  Voltaic  series, 
there  was  no  known  mode  of  rivalling  the  heat  produced  by  large 
burning  glasses  and  mirrors.  These  have  been  already  mentioned, 
perhaps  sufficiently,  in  the  account  of  heat  and  light. 

It  is  not  in  our  power  to  say  what  is  the  nature  of  the  sun,  and  for 
aught  we  know,  the  popular  opinion  that  his  body  is  a  globe  of  ignited 
matter,  may  be  correct.f 

(b.)  Combustion. — After  the  solar  influence,  this  is  the  most  im- 
portant source  of  heat ;  it  is  very  completely  under  our  command  $ 
it  can  be  applied  when  and  where  we  please,  and  varies  from  ex- 


*  Dr.  Hare. 

t  Dr.  Herschel's  ideas  of  the  nature  of  the  sun,  were  peculiar.  He  supposed  the 
sun's  body  to  be  opake  ;  that  his  atmosphere  has  two  strata  of  clouds ;  the  one  opake 
and  the  other  phosphorescent ;  the  latter  he  supposes  to  be  the  highest,  and  that  they 
emit  the  light ;  that  when  the  clouds  are  broken  and  ragged,  the  sun's  opake  body 
is  seen  through  the  clouds.  The  fruitfulness  of  different  seasons  he  supposed  to  be 
connected  with  the  quantity  of  light  emitted  fvom  the  luminous  clouds  of  the  sun. — 
Phil.  Trans.  1801..  ' 


128 


SOURCES  OF  HEAT  AND  COLD. 


treme  mildness  to  extreme  intensity.  Common  fires,  in  fire  places 
and  stoves  ; '  Argarid's  lamp  ;  oil  lamps  ;  spirit  lamps ;  gaslights;  a 
smith's  forge ;  the  furnaces  of  the  arts  and  of  the  laboratory  ;  can- 
dles ;  the  mouth  blowpipe,  and  that  fed  by  oxygen  and  hydrogen 
gases,  are  all  familiar  instances,  in  which  combustion  is  seen. 

Combustion  is  mentioned  with  propriety,  both  as  a  source  and  as 
an  effect  of  heat ;  for  generally,  it  does  not  commence  and  proceed 
without  an  augmented  temperature,  and  it  raises  the  temperature  in 
turn. 

I  shall  omit  the  description  of  common  furnaces,  and  subjoin  that 


of  the  following  instruments. 
1.   The  Mouth  I 


L    .— Dr.  Hare,  Itol. 

J.    J.  ? 


"  As  fire  is  quickened,  by  a  blast  from  a  bellows,  so  a  flame  may 
be  excited  by  a  stream  of  air  propelled  through  it  from  the  blow- 
pipe." 

"  The  instrument,  known  by  the  abovementioned  appellation,  is 
here  represented  in  one  of  its  best  forms,.  It  is  susceptible  of  vari- 
ous other  constructions  ;  all  that  is  essential  being  a  pipe  of  a  size  at 
one  end  suitable  to  be  received  into  the  mouth,  and  towards  the 
other  end,  having  a  bend,  nearly  rectangular,  beyond  which  the  bore 
converges  to  a  perforation,  rather  too  small  for  the  admission  of  a 
common  pin.  There  is  usually,  however,  an  enlargement,  to  catch 
.the  condensed  moisture  of  the  breath,  as  in  this  figure." 

Berzelius  has  in  an  octavo  volume,  illustrating,  the  extreme  utility  of 
the  mouth  blowpipe,  with  which  Gahn  discovered  tin  in  a  mineral 
containing  only  one  per  cent.,  which  had  escaped  detection  by  an- 
alysis ;  and  he  extracted  also  copper  from  the  ashes  of  a  quarter  of 
a  sheet  of  paper. 

-t 

2.  Lamp  without  a  flame.* 
r  j 

"  About  the  wick  of  a  spirit  lamp,  a  fine  wire  oi 
platina  is  coiled,  so  as  to  leave  a  spiral  interstice  be- 
tween the  parts  of  the  spiral  formed  by  the  wire  ;  a 
few  turns  of  which  should  rise  above  the  wick." 

"  If  the  lamp  be  lighted ;  on  blowing  out  the  flame, 
the  wire  will  be  found  to  remain  red  hot,  as  it  re- 
tains sufficient  heat  to  support  the  combustion  of  the 
alcoholic  vapor,  although  the  temperature  be  inade- 
quate to  constitute,  or  produce  inflammation." 


See  Am.  Jour.  Vol.  IV.  p.  328. 


SOURCES  OF  HEAT  AND  COLD. 


129 


"  Instead  of  blowing  out  the  flame,  it  is  better  to  put  an  extin- 
guisher over  it,  for  as  short  a  time  as  will  cause  the  flame  to  disap- 
pear. For  this  purpose,  a  small  phial,  or  test  tube,  is  preferable  to 
the  metallic  cap  usually  employed." 

"  The  metallic  coil  appears  to  serve  as  a  reservoir  for  the  caloric, 
and  gives  to  the  combustion  a  stability,  in  which  it  would  otherwise 
be  deficient." 

"  There  is  some  analogy  between  the  operation  of  the  wire,  in  act- 
ing as  a  reservoir  of  heat  in  this  chemical  process,  and  that  of  a  fly 
wheel,  as  a  reservoir  of  momentum,  in  equalizing  the  motion  of  ma- 
chinery." 

Dr.  Hare  introduced  a  blowpipe,  in  which  the  air  was  propelled 
by  hydrostatic  pressure  ;  and  in  this  manner  he  used  also  the  oxygen 
and  hydrogen  gases.*  I  have  found  such  a  blowpipe  very  useful, 
and  it  will  be  mentioned  again  in  this  work. 

The  blowpipe  of  the  enameler  and  of  the  thermometer  maker,  is 
fed  by  a  double  bellows,  worked  by  the  foot,  and  terminates  in  a 
pointed  tube,  which  rises  above  a  table,  and  thus  supplies  a  lamp. 

3.  Alcohol  Blowpipe,. 

"  A  flame  resembling  that 
of  the  enameler's  lamp,  may 
be  produced  by  a  small  boiler, 
A,  containing  alcohol,  in  which 
alcoholic  vapor  is  generated, 
as  steam  is,  by  the  boiler  of  a 
steam  engine." 

"  The  vapor  thus  generated 
is  substituted  for  air  in  the  blast 
of  the  blowpipe,  being  directed 
upon  the   flame  of  a  lamp  in 
the  same  way,  by  means  of  a 
pipe  proceeding  from  the  boil- 
er, and  terminating  in  a  beak, 
with   a   capillary   orifice,   B. 
the  boiler  is  furnished  with  a 
safety  valve,  V." 
"  It  may  be  objected  to  flame  thus  excited,  that  as  the  oxygen  is 
not  so  copiously  supplied,  as  when  a  stream  of  air  is  used,  the  oxide 
of  lead  in  flint  glass  tubes  is  reduced  by  it,  and  the  glass  consequently 
blackened." 

'  The  apparatus  here  represented,  is  furnished  with  an  adjusting 
screw,  S,  by  which  the  height  of  the  boiler  is  regulated  ;  while  the 


See  his  Compendium,  p.  73. 
17 


130 


SOURCES  OF  HEAT  AND  COLD. 


communication  is  preserved  between  it  and  the  beak,  by  means  of  G 
tube  sliding  through  a  stuffing  box,  C,  which  surmounts  a  larger  tube 
to  which  the  beak  is  soldered."* 

4.  A  new  modification  of  the  Blowpipe  by  Alcohol. 

11  This  figure  represents  an  improv- 
ed blowpipe,  by  alcohol.  In  the  ordi- 
nary construction  of  that  instrument, 
the  inflammation  is  kept  up,  by  pass- 
ing a  jet  of  alcoholic  vapor  through 
the  flame  of  a  lamp,  supported,  as  is 
usual  by  a  wick.  The  inflammation 
of  the  jet  cannot  be  sustained  with- 
out the  heat  of  the  lamp  flame  ;  since 
the  combustion  does  not  proceed  with 
sufficient  rapidity  to  prevent  the  in- 
flamed portion  from  being  carried  too 
far  from  the  orifice  of  the  pipe  ;  and 
being  so  much  cooled  by  an  admix- 
ture of  air,  as  to  be  extinguished. 
By  using  two  jets  of  vapor  in  opposi- 
tion to  each  other,  I  find  the  inflam- 
mation may  be  sustained  without  a 
lamp.  If  one  part  of  oil  of  turpen- 
tine, with  seven  of  alcohol  be  used,  the 
flame  becomes  as  luminous  as  a  gas 
light." 

"  In  order  to  equalize  and  regulate 
the  efflux,  I  have  contrived  a  boiler  like  a  gasometer.  It  consists  of 
two  concentric  cylinders,  open  at  top,  leaving  an  interstice  of  about 
one  quarter  of  an  inch  between  them  ;  and  a  third  cylinder,  open  at 
bottom,  which  slides  up  and  down  in  the  interstice.  The  interstice 
being  filled  with  boiling  water,  and  alcohol  introduced  into  the  inner- 
most cylinder,  it  soon  boils  and  escapes  by  the  pipes.  These  pass 
through  stuffing  boxes  in  the  bottom  of  the  cylinder.  Hence  their 
orifices,  and  of  course  the  flame,  may  be  made  to  approach  to  or  re- 
cede from  the  boiler.  It  must  be  obvious  that  the  introduction  of  the 
alcohol  requires  the  temporary  removal  of  the  intermediate  cylinder.'' 


*  "Stuffing  box  is  the  technical  name  given  by  mechanics  to  a  small  hollow  me- 
tallic cylinder,  in  which,  by  means  of  another  cylinder  acted  upon  by  screws,  some 
cotton,  tow,  leather,  or  other  elastic  substance,  is  packed  about  a  rod,  50  as  to  allow 
it  to  move  to  and  fro  without  permitting  any  fluid  to  escape  from  the  vessel  into  which 
it  may  enter/" 


SOURCES  OF  HEAT  AND  COLD. 


13] 


(c.)  Chemical  action  without  combustion;  that  is  to  say,  without 
combustion  to  begin  with  ;  combustion  is  not  used  as  a  means  of  rais- 
ing the  heat,  although  this  mode  of  evolving  heat  may  end  in  com~ 
bustion,  provided  any  ingredient  in  the  mixture  is  combustible  ;  e.  g. 
as  in  the  case  of  nitric  acid  acting  on  alcohol  or  oils,  dense  or  vola- 
tile. Fermentation  of  hay  may  produce  combustion. 

Spontaneous  combustions  proceed  in  many  instances,  from  chem- 
ical action,  as  in  cases  where  oils,  tallow,  paints,  and  similar  sub- 
stances, are  in  contact  with  flax,  cotton  or  hemp.  Tanner's  bark 
and  horse  manure,  by  fermentation,  produce  heat  for  the  green 
house,  and  for  some  processes  in  the  arts. 

Most  of  the  cases  under  this  head  belong  to  capacity  and  specific 
heat,  and  the  doctrine  has  been  partly  anticipated.  Many  more  in- 
stances will  follow.  At  present  I  add  only  the  following  from  Dr. 
Hare. 

5.  Boiling  heat  produced,  by  the  mixture  of  sulphuric  acid  vnth 
water. 


"  Into  the  inner  tube,  represented  in  the 
adjoining  figure,  introduce  about  as  much 
alcohol,  colored,  to  render  it  more  discern- 
ible, as  will  occupy  it  to  the  height  of  three 
or  four  inches.  Next  pour  water  into  the 
outer  tube,  till  it  reaches  about  one  third  as 
high  as  the  liquid  within  ;  and  afterwards 
add  to  the  water,  about  three  times  its 
bulk  of  concentrated  sulphuric  acid.  The 
liquid  in  the  inner  tube  will  soon  boil  vio- 
lently, so  as  to  rise  in  a  foam." 


6.  Chemical  combination,  attended  by  decomposition,  as  the  means 
of  evolving  caloric. 

"  Instances  of  that  species  of  corpuscular  reaction,  which  comes  un- 
der this  head,  will  be  hereafter  mentioned  in  their  proper  places.  The 
extrication  of  caloric,  which  is  usually  more  or  less  a  consequence  of 


132  SOURCES  OF  HEAT  AND  COLD. 

intense  chemical  reaction,  is  a  collateral,  rather  than  a  necessary  con- 
sequence of  it. 

"As  an  example  in  which  caloric  is  rendered  sensible,  by  the 
method  in  question,  the  inflammation  of  turpentine  by  a  mixture  of 
nitric  acid,  with  sulphuric  acid,  may  be  adduced." 

"  The  inflammation  of  alcohol,  or  oil  of  turpentine,  by  means  of 
a  chlorate  and  sulphuric  acid,  as  represented  by  this  figure,  affords 
another  exemplification  perfectly  in  point." 


"  About  as  much  chlorate  of  potash  as  may  be  piled  upon  a  half 
c'ent,  being  deposited  in  a  heap,  in  the  inflammable  liquid,  and  con- 
centrated sulphuric  acid  being  poured  upon  the  heap,  the  liquid  is  in- 
flamed." 

"  As  portions  of  the  liquid  are  sometimes  projected  into  the  air,  in 
a  state  of  inflammation,  it  is  expedient,  for  the  security  of  the  opera- 
tor, to  have  the  glass,  used  to  convey  the  acid,  fastened  to  the  end  of 
a  rod." 

(df.)  Electricity  and  Galvanism. — The  modes  of  excitement  are 
peculiar ;  generally  they  are  well  known,  but  they  belong  either  to  a 
different  science,  or  to  a  different  part  of  this  science. 

The  applications  of  the  heat  evolved  in  this  way,  are  extremely 
useful  to  the  chemist ;  the  power  is  conveyed,  conveniently,  into  and 
through  the  interior  of  vessels,  and  thus  gives  us  a  furnace  heat  with- 
out its  inconveniences.  The  heat  is  mild  or  intense  at  pleasure  ;  no 
heat,  probably  not  even  that  of  lightning,  exceeds  that  produced  by 
electrical  and  galvanic  arrangements.  The  decomposing  powers  con- 
nected with  common  and  galvanic  electricity,  produce  the  most  curi- 
ous and  important  results,  dividing  the  material  world  between  the 
opposite  poles,  but  this  part  of  the  subject  is  not  appropriate  to  the 
present  topic.  The  facts  and  the  instruments  relating  to  Galvanism 
are  reserved  for  another  place,  except  that  I  shall  introduce  here 
from  Dr.  Hare,  an  instrument  equally  simple  and  useful. 


SOURCES  OF  HEAT  AND  COLD. 
The  galvanophorus,  or  galvanic  substitute  for  the  electrophones 


"  The  preceding  figure  represents  an  instrument  for  igniting  a. 
lamp,  by  means  of  a  galvanic  discharge,  from  a  calorimotor." 

"  The  plunger,  P,  being  depressed,  by  means  of  the  handle  at- 
tached to  it,  some  acid,  contained  in  the  box,  B,  is  displaced,  so  as 
to  rise  among  the  galvanic  plates.  By  the  consequent  evolution  of 
the  galvanic  fluid,  a  platina  wire  (fastened  between  the  brass  rods 
forming  the  poles  of  the  calorimotor,  and  projecting  over  the  lamp,  as 
seen  at  R,)  is  rendered  white  hot,  and  a  filament  of  the  wick,  pre- 
viously laid  upon  it,  is  inflamed." 

"  The  weight,  W,  acts  as  a  counterpoise  to  the  plunger,  and  keeps 
it  out  of  the  acid,  when  it  is  not  depressed  by  the  hand." 

(e.)  Condensation  of  aeriform  bodies  by  pressure  and  cold. — 
This  topic  is  already  anticipated  under  specific  heat  and  vapors. 
Vapors  and  gas  mechanically  condensed,  as  by  the  syringe  and  piston, 
give  out  heat ;  vapors  impart  heat  to  colder  bodies,  as  in  the  distill- 
ing apparatus  with  its  condenser,  already  mentioned.  Compressed 
oxygen  and  chlorine  give  out  light,  and  these  gases  are  said  to  be 
the  only  simple  ones  that  become  luminous  by  pressure. 

(/.)  Condensation  of  solids  by  mechanical  action  including  fric- 
tion and  percussion. — The  flint  and  steel  in  collision,  or  two  quartz 
stones  struck  forcibly  together ;  any  hard  stone  firmly  held  upon  a 
revolving  grit  stone  ;  the  vigorous  rubbing  together  of  two  sticks  ;  the 
friction  of  branches  of  trees  in  stormy  weather ;  of  axles  in  carts  and 
wagons  and  of  various  pnrts  of  powerful  machinery  ;  of  the  axles  in 


134  SOURCES  OP  HEAT  AND  COLD. 

sheaves  or  blocks  of  running  tackle*  on  board  of  ships ;  of  ropes,  pass- 
ing rapidly  over  a  gunwale,  as  when  a  whale  is  harpooned ;  friction  in 
the  boring  of  cannon  and  muskets  j  of  a  rope  running  rapidly  through 
the  hand  ;  of  the  hand  rubbed  on  a  stair  rail,  or  on  one's  woolen  coat 
sleeve  ;  all  these  and  many  others  are  instances  of  heat  evolved  on 
this  principle. 

The  rotary  match  box  gives  sparks  by  the  collision  of  a  rapidly  revol- 
ving steel  with  flint,  and  a  similar  instrument  called  the  steel  mill,  was 
used  to  give  light  in  coal  mines  before  the  invention  of  the  safety  lamp. 

An  iron  bar  grows  hot  enough,  by  vigorous  hammering,  to  kindle 
shavings,  and  lead  will  by  the  same  treatment  kindle  phosphorus. 

Wood,  in  rapid  revolution,  "  may  be  carbonized  throughout  the 
circle  of  contact,  by  holding  against  it  another  piece  properly  sharp- 
ened, and  one  cork  rubbed  against  another  will  become  hot  enough  to 
kindle  phosphorus. "f  A  disk  of  soft  iron  rapidly  revolving  by  ma- 
chinery, will  easily  cut  in  twof  the  hardest  steel  saw  plate,  or  the 
best  file. 

(g.)  Vital  action. — This  is  evidently  a  source  of  heat,  although 
in  a  way  not  perhaps  fully  understood.  There  can  be  no  doubt  that 
oxygen,  acting  in  respiration,  is  an  important  agent  in  producing  and 
sustaining  it  ;  it  appears  probable  also  that  secretion,  connected  with 
the  influence  of  the  nerves,  is  concerned,  and  some  facts  countenance 
the  opinion  that  galvanic  agencies  are  not  dormant. 

Whatever  may  be  usefully  said  on  the  latter  subject,  belongs  to  a 
more  advanced  stage  of  this  work. 

II.  THE  SOURCES  OF  COLD. 

1.  Evaporation, 

2.  Rarefaction, 

3.  Chemical  action. 

1.  Evaporation. — The  general  facts  on  this  subject  have  been  al- 
ready stated.  Whenever  a  body  passes  to  the  aeriform  state,  it  ab- 
sorbs heat  to  turn  it  into  vapor,  and  thus  cools  the  contiguous  bodies. 
Sensible  cold  is  produced  by  the  evaporation  of  water,  more  by  that 
of  alcohol,  and  most  of  all  by  that  of  ether  or  carburet  of  sulphur, 
or  liquid  sulphurous  acid,  whether  measured  by  our  organs  or  by  the 
thermometer.  We  have  already  seen  that  water  is  frozen  by  the 
evaporation  of  ether,  both  in  the  exhausted  receiver  of  the  air  pump, 
and  in  a  tube  in  the  atmosphere.  The  mercury  in  a  thermometer 
ball,  wet  with  water  and  having  a  current  of  air  blowing  upon  it, 
will  fall  5°  ;  if  with  alcohol,  12°,  and  if  with  ether,  30°.— -Murray. 


*  See  Lt.  Glynn  in  Am.  Jour.  Vol.  XIV,  p.  196,  and  Capt.  Parry's  2d  Voyage,  New 
York  Ed.  p.  212.  "  The  weight  of  the  ice  every  moment  increasing,  obliged  us 
to  veer  on  the  hawsers,  whose  friction  was  so  great  as  nearly  to  cut  thtough  the  bit 
heads,  and  ultimately  set  them  on  fire,  so  that  it  became  requisite  for  people  to  at- 
tend with  buckets  of  water." — Parry. 

t  Dr.  Hare.  t  See  Am.  Jour.  Vol.  VI,  p.  336. 


SOURCES  OF  HEAT  AND  COLD.  135 

With  a  rapid  exhaustion  by  the  air  pump,  mercury  in  a  thermome- 
ter ball,  if  the  ball  be  wrapped  in  flannel  or  fleecy  hosiery  and  dipped 
n  ether  ior  sulphuret  of  carbon,  will  be  frozen  in  two  or  three  minutes. 

Evaporation  is  very  extensive  in  its  natural  operation,  and  its  uni- 
versal prevalence  is  one  of  the  great  causes  which  prevents  the  accu- 
mulation of  heat  on  our  globe,  and  which  therefore  tends  very  much 
to  preserve  the  equilibrium  of  its  temperature.  It  is  also  occasion- 
ally of  use  in  the  operations  of  art,  and  is  sometimes  employed  as  we 
have  already  seen,  to  depress  the  temperature  of  particular  bodies. 

2.  Rarefaction. — This  is  intimately  connected  with  evaporation, 
and  depends  upon  the  same  principle.     As  condensation  produces 
heat,  so  rarefaction  generates  cold.     It  is  seen  chiefly  in  the  aeriform 
fluids.     The  remarkable  example  at  the  fountain  of  Hiero,  has  been 
already  mentioned.     In  air  pump  experiments,  the  thermometer  falls 
several  degrees,  and  Dr.  Darwin  observed,  "that  if,  in  the  stream 
of  air  issuing  from  the  receiver  of  an  air  gun,  in  which  it  had  been 
compressed,  a  thermometer  were  placed,  it  sunk  from  5°  to  7°." 

In  the  first  instance,  it  produces  heat  by  its  condensation,  and  in- 
stantly after,  cold  by  its  rarefaction. 

Air,  condensed  into  a  reservoir  and  suddenly  liberated  from  an  or- 
ifice, produces  a  considerable  degree  of  cold  :  Gay  Lussac  found  it 
equal  to  50°  of  Fahr.* 

If  heat  must  be  absorbed  in  evaporation  or  gazification,  in  order  to 
produce  an  aeriform  body,  more  heat  is  required  to  enlarge  its  bulk 
after  it  is  produced,  and,  as  its  particles  are  repulsive,  when  the  pres- 
sure which  retains  them  within  a  certain  distance  is  diminished,  the 
particles  recede  and  caloric  is  absorbed,  for,  otherwise  their  repellent 
power  could  not  be  maintained  at  increasing  distances,  and  they  would 
again  approach ;  when  they  are  forcibly  brought  together  anew  by 
compression,  the  heat  is  again  given  out. 

3.  Chemical  action. — Cold  is  produced  during  the  chemical  ac- 
tion of  those  substances  whose  capacity  is  by  the  union   enlarged, 
and  which  therefore  absorb  caloric.     The  immediate  effect  of  chem- 
ical union  is  a  mutual  penetration  of  particles,  and  therefore  an  in- 
crease of  specific  gravity,  and  of  course  an  emergence  of  heat ;  but 
it  often  happens  also  that  there  is  an  enlargement  of  capacity  and  the 
absorption  of  heat  which  follows  from  this  cause,  is  frequently  suffi- 
cient to  generate  a  considerable  degree  of  cold.     Sulphuric  acid  and 
snow  afford  us  an  illustration  of  both  these  remarks  ;  when  first  min- 
gled they  produce  heat  for  an  instant,  owing  to  the  energy  of  their 
combination,  but  immediately  after,  cold  is  produced  because  water 
is  of  the  capacity  of  ten  for  caloric,  while  ice  is  only  nine. 

*  Probably  from  the  medium  of  temperature.  "  The  cold  will,  however,  depend 
on  the  previous  condensation  of  the  air."  Dr.  Torrey  informs  me  that  he  makes 
this  experiment  with  Newman's  blowpipe,  and  that,  with  an  air  thermometer,  the 
e:ffect  can  be  witnessed  at  a  considerable  distance. 


136 


SOURCES  OF  HEAT  AND  COLD. 


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ATTRACTION.  137 


SEC.  IV.    ATTRACTION.* 

By  attraction,  we  mean  the  tendency  of  bodies  to  approximate,  and 
also  the  unknown  cause  of  that  tendency. — In  its  most  general  sense, 
it  extends  to  atoms  and  masses  reciprocally,  and  to  every  distance. 

It  is  the  bond  of  the  universe.;  it  appears  to  depend  in  general  on  no 
proximate  cause,  but  to  emanate  at  once  from  the  will  of  the  Deity. 

Counteracted  and  modified  by  the  powers  of  repulsion  and  pro- 
jection, it  keeps  every  thing  in  harmonious  equilibrium. 

It  is  unknown  whether  it  arises,  in  all  its  varieties,  from  the  modifi- 
cations of  one  cause,  or  whether  there  are  several,  giving  origin  to  the 
different  kinds  of  attraction. 

However  this  may  be,  it  is  most  convenient  to  consider  the  sub- 
ject under  different  heads. 

1.  GRAVITATION. 

2.  MAGNETISM. 

3.  GALVANIC  ELECTRICITY. 

4.  COHESION  AND  AGGREGATION. 

5.  CHEMICAL  ATTRACTION  OR  AFFINITY. 

1.  GRAVITATION. 

(a.)  It  extends  to  every  thing,  to  all  quantities  of  matter,  and  to 
all  distances. 

(6.)  Its  force  is  directly  as  the  quantity  of  matter,  and  inversely  as 
the  square  of  the  distance. — The  quantity  of  matter,  in  different 
cases,  being  as  1.2.  3.  4,  the  attracting  force  at  a  given  distance,  will 
be  as  those  numbers  directly ;  but  the  same  body  being  placed  suc- 
cessively at  the  distances  1.  2.  3.4,  the  attracting  force  will  be  ex- 
pressed inversely,  by  1.  4.  9.  16,  that  is,  at  the  distance  2  it  will  be 
J,  at  3,  i,  and  at  4,  ,',,,  as  great  as  it  was  at  the  distance  1. 

We  are  familiar  with  the  effects  of  gravitation,  and  therefore  re- 
gard them  as  natural ;  they  are  so  to  our  habits,  but  only  in  obedi- 
ence to  an  established  law ;  if  the  law  had  been  different,  our  habits 
would  have  been  accommodated  to  it. 

Were  there  no  attraction  towards  the  earth,  a  stone  thrown  into  the 
air  would  not  return,  and  would  stop  only  from  the  resistance  of  some 
medium,  or  of  some  other  body  which  it  might  encounter. 

(c.)  The  projectile  power  modifies  the  gravitating  force,  so  that 
the  planets  move  in  elliptical  orbits,  and  neither  fall  to  the  centre  of 
motion,  nor  move  off  in  tangents  to  the  curve  of  the  orbit. 


*  I  have  been  accustomed  to  give,  in  my  lectures,  a  very  general  sketch  of  the 
different  varieties  of  attraction,  that  affinity  may  be  the  better  understood,  and  shall 
pursue  the  same  course  in  this  work. 

18 


IBS  ATTRACTION. 

2.  MAGNETISM. 

(a.)  This  is  a  power  usually  manifested  in  iron  or  steel,  after  hav- 
ing received  particular  treatment,  or  after  having  been  for  some  time  in 
a  particular  position. 

(b.)  It  belongs  also  to  nickel,  and  to  cobalt,  which  like  nickel, 
is  found  to  be  the  more  magnetic,  the  purer  it  is  made. 

(c.)  Magnetism  resides  also  in  the  earth. — The  magnetic  poles  are 
not  coincident  with  the  poles  of  revolution.     In  the  Arctic  region, 
the  magnetic  pole  is*  in  69°  16'  of  N.  lat.  and  98°  8'  W.  lon.f 
d.)  Repulsion  as  wdl  as  attraction  is  predicable  of  magnetism, 
e.)  Similar  magnetic  poles  repel,  and  opposite  poles  attract. 

f.)  Magnetism  is  connected,  in  some  mysterious  manner,  with  the 
other  imponderable  powers,  light,  heat,  and  electricity. 

Sg.)   The  solar  rays,  especially  the  violet,  magnetize  a  needle.^ 
h.)    The  calorimotor  evolves  heat  with  great  energy,  but  its  elec- 
tricity is  of  a  very  low  intensity  ;  still,  it  magnetizes  needles  power- 
fully, when  there  is  no  light  perceptible. 

(i.)  Similar  effects,  in  a  greater  or  less  degree,  are  produced  by 
all  the  varieties  of  galvanic  apparatus  ;  all  the  known  imponderable 
fluids  being  occasionally  present  together. 

0/0  ^e  cannot  say,  therefore,  whether  magnetism  is  a  distinct 
power,  or  a  property  or  appendage  of  one  or  more,  or  of  all  the  other 
imponderable  powers. — The  magnetic  power,  both  in  its  attractions 
and  repulsions,  is  pleasingly  exhibited  by  magnetic  needles,  fish,  boats, 
and  balls,  by  the  horse  shoe  magnet,  bar  magnet,  &c.  Many  articles 
of  iron  and  steel  become  magnets  spontaneously,  especially  such  as 
have  stood  long  vertically  or  nearly  so,  and  more  especially,  if  in  the 
magnetic  meridian.  Magnetism  is  excited  also  by  rapid  rotary  mo- 
tion. 

3.  GALVANISM 

1.  Requires,  and  will  receive  a  distinct  statement  near  the  end 
of  this  work,  but  as  this  remarkable  power  actually  arranges  in  a 
natural  method,  all  the  elements  and  compound  principles  of  matter, 
it  is  mentioned  here  among  the  general  powers. 

(a.)  Mode  of  excitement. — Nearly  as  various  as  matter,  almost  all 
substances  of  different  natures,  or  sometimes  the  same  substance  in 
different  conditions,  arranged  in  a  particular  connexion,  will  serve  to 


*  Or  was  at  the  lime  of  Captain  Parry's  late  voyages ;  I  Icnow  cot  whether  any 
observations  have  since  been  made,  to  ascertain  its  constancy  in  latitude ;  the  varia- 
tions of  the  needle  E.  and  W.,  eecm  to  prove  that  the  magnetic  pole  varies  in  longi- 
tude, t  Am.  Jour.  Vol.  XVI,  p.  149. 

t  Morrichini's  and  Mrs.  Somerville^s  experiments  on  magnetizing  needles,  arc 
said  to  have  failed  in  skilful  hands  ;  it  is  suggested  that  the  needles  might  have  been 
magnetized  before.  The  editor  of  the  Pbi]os.  Magazine,  new  series,  Vol.  IV,  p 
221,  thinks  that,  at  least,  the  magnetism  was  increased. 


ATTRACTION.  139 

render  this  power  perceptible.  Common  electricity  is  also  excited 
in  many  ways,  but  most  usually  by  the  friction  of  glass  or  resin. 

(6.)  Mode  of  exciting  the  Voltaic  power. — Certain  combina- 
tions of  metals,  usually  zinc  and  copper,  with  fluids,  especially  saline 
and  acid  fluids,  producing  opposite  polarity  at  the  two  extremes 
of  the  series. 

(c.)  .Mode  of  receiving  and  transmitting  the  power. — By  conduc- 
tors, uniting  the  poles ;  they  are  commonly  wires,  and  are  often 
pointed  with  well  prepared  charcoal. 

(d.)  Nature  of  the  power. — It  has  been  commonly  regarded  as 
the  same  with  electricity ;  like  that  it  is  attended  by  light,  heat,  and 
magnetism,  variously  modified  and  combined  in  different  proportions, 
in  different  kinds  of  apparatus  ;  so  that  one  predominates  in  one  kind 
and  another  in  another.  It  is  clear  that  it  is  not  electricity  merely. 

(e.)  Sensible  and  demonstrable  effects. — Attractions  and  repul- 
sions, as  in  common  electricity  ;  similar  poles  repelling  and  opposite 
attracting.  All  elements  and  all  compound  principles,  when  placed 
in  the  electro-galvanic  circuit,  being  for  the  time  endued  with  polari- 
ty, chemical  decompositions  are  thus  produced.  '  Muscular  shocks 
are  also  among  the  effects  produced  by  this  power,  as  well  as  light, 
heat,  and  magnetism,  which  have  been  already  mentioned. 

(/*.)  Mode  of  effecting  the  decompositions,  by  bringing  the  con- 
necting points  into  contact  with  the  particular  substance. 

(g.)  Classification  of  the  elementary  bodies. — Oxygen,  iodine,  and 
chlorine,  are  attracted  to  the  positive  pole,  and  are  therefore  said  to 
be  electro-negative. 

The  combustibles  and  metals  are  attracted  to  the  negative  pole, 
and  are  therefore  said  to  be  electro-positive. 

(h.)  Classification  of  the  principal  proximate  principles  in  the  com- 
pound bodies. — The  acids  go  to  the  positive  pole  ;  the  earths,  alka- 
lies and  oxides  of  metals,  to  the  negative. 

(i.)  Galvanic  electricity  is  a  powerful  agent  in  decomposition  ;  it 
is  more  energetic,  and  it  is  also  more  manageable  than  common  elec- 
tricity. 

(j.)  The  arrangement  of  the  principles  of  bodies  under  this  pow- 
er, will  be  mentioned  as  we  come  to  them  individually. 

(k.)  The  other  effects  are  not  material  in  our  present  state  of  ad- 
vancement ;  they  will  be  mentioned  in  their  proper  place. 

It  is  supposed,  that  the  electrical  and  magnetic  attractions  are  gov- 
erned by  the  same  general  law  with  gravitation. 

4.  COHESION — ADHESION — AGGREGATION. 

(a.)  Cohesion  is  a  union  of  parts,  without  change  of  properties. 
— The  particles  of  a  bar  of  iron  cohere  ;  this  force  gives  the  iron 
its  strength  ;  those  of  water  cohere  but  feebly ;  hence  it  has  no 
strength  ;  those  of  moist  dough  cohere  more  than  water,  &c.  These 


140  ATTRACTION. 

are  examples  of  union  where  the  minutest  parts  are  of  imperceptible 
magnitude. 

Adhesion.* — Two  plates  of  glass  or  two  of  metal,  or  one  of  glass 
and  one  of  metal,  when  moistened  or  oiled,  adhere,  with  considerable 
force ;  with  still  more  force,  two  leaden  hemispheres  made  by  split- 
ting a  bullet,  and  pressing  the  surfaces  together  with  a  wringing  or 
twisting  motion.  If  furnished  with  hooks,  the  parts  of  the  bullet  may 
be  suspended,  and  will  support  a  considerable  weight  that  may  be 
gradually  increased  for  some  time,  before  the  hemispheres  will  part.f 

(b.)  The  cohesion  of  homogeneous^  particles  is  often  termed  aggre- 
gation, and  masses  made  up  in  that  manner  are  said  to  be  aggregates. 

(c.)  The  word  adhesion  may  be  used  to  denote  the  union  between 
surfaces  of  perceptible  magnitude,  whether  similar  or  dissimilar  in 
their  nature. 

(d.)  Cohesion  produces  augmentation  of  volume,  and  frequent- 
ly a  change  inform,  but  no  change  in  properties. — The  dust  of  mar- 
ble is  the  same  substance  with  the  stratum  or  mountain  of  marble 
which  afforded  it ;  it  contains  the  same  elements,  and  in  the  same 
proportions.  The  elements  are  united  by  affinity  or  chemical  attrac- 
tion ;  the  compound  particles  produced  by  the  union  of  the  elements, 
are  united  by  cohesion. 

(e.)  Mhesion  of  surfaces  of  perceptible  extent  produces  no  change 
in  properties. — Generally  the  union  of  such  surfaces  is  feeble.  That 
particular  mode  of  corpuscular  union  which  is  called  cohesion,  is  the 
source  of  the  different  strength  of  materials,  as  of  lead,  iron,  wood,  &ic. 

(/.)  The  attraction  which  produces  the  union  of  particles  is  often 
called  corpuscular  attraction. — It  is  quite  immaterial  whether  the  par- 
ticles be  simple,  as  those  of  single  metals,  or  compound  as  those  of 
metallic  alloys  or  wood  ;  in  either  case,  the  state  of  the  body  results 
from  the  union  of  minute  particles,  which  are  for  this  purpose  regard- 
ed as  mechanically  simple,  whether  chemically  so,  or  noU 

The  union  of  dissimilar  particles,  as  will  be  hereafter  seen,  is  re- 
ferred to  chemical  action.  Chemical  union  may  first  connect  dis- 
similar particles,  as  zinc  and  copper ;  and  the  compound,  which  is  in 
that  case  called  brass,  is  composed  of  panicles,  that  are  regarded  as 
mechanically  simple,  and  are  called  integrant  particles ;  while  the 
others  are  called  constituent  particles. 


*  Jldhesion  is  merely  a  word  of  convenience  ;  the  power  that  unites  surfaces  of 
perceptible  magnitude,  and  that  which  unites  particles  in  aggregation,  is  doubtless 
the  same. 

t  This  effect  evidently  depends,  in  part,  upon  the  furrows  on  the  surface  of  the  lead 
which  are  brought  into  close  contact  by  the  twist  that  is  given  in  pressing  them  to- 
gether, with  a  screwing  motion  ;  when  polished,  it  is  difficult  to  make  thorn  adhere. 

I  Heterogeneous  particles  will  also  unite,  but  the  result  is  not  an  aggregate ;  it  is 
a  new  body,  whose  particles  are  connected  not  by  mechanical  but  by  chemical  at- 
traction. 


ATTRACTION.  141 

(G.)  CRYSTALLIZATION  is  THE  RESULT  OF  THE  ATTRACTION  OF 

AGGREGATION. 

(h.)  A  crystal  is  a  symmetrical  solid, produced  by  the  union  of  in- 
tegrant particles.* 

(i.)  Natural  crystals  are  numerous,  and  art  produces  many  more; 
every  good  mineral  cabinet  exhibits  great  numbers  of  the  former,  and 
every  good  chemical  collection  of  the  latter. 

(j.)  Destruction  or  great  diminution  of  the  power  of  cohesion 
is  an  indispensable  preliminary. — This  is  effected  either  by  so- 
lution in  a  fluid,  or  by  the  aid  of  heat  producing  fluidity  or  the  state 
of  vapor.  In  the  former  case,  it  is  necessary  to  drive  off  part  of  the 
solvent  by  heat ;  in  the  latter,  merely  to  allow  the  fluid  to  cool,  or  the 
vapor  to  be  condensed,  in  order  that  crystals  may  be  formed.  Cer- 
tain circumstances  are,  however,  necessary  to  be  attended  to  in  order 
to  success.  If  the  solvent  be  very  rapidly  expelled  by  the  aid  of  a 
high  temperature,  or,  if  the  fused  body  be  suddenly  exposed  to  an  in- 
tense cold,  either  a  shapeless  mass  will  be  formed,  or  only  confused 
and  irregular  crystals.  In  general,  fine  crystals  are  obtained  only  by 
slow  evaporation  and  by  slow  cooling.  Water  and  most  of  the  metals 
are  examples  of  bodies  that  crystallize  by  a  mere  reduction  of  tem- 
perature. A  saturated  solution  of  sulphate  of  soda,  boiled  and  cork- 
ed in  that  state,  does  not  become  solid  on  cooling,  but  on  letting  in 
the  air ;  agitating  it  by  a  jerk  or  jar,  or  dropping  in  a  crystal,  it  con- 
geals and  heat  is  evolved,  sufficient  to  melt  it  again.  If  a  string  or 
mark  be  placed  on  the  neck  of  the  vessel,  it  will  be  seen  that  the  mass 
has  been  expanded  by  the  crystallization.  It  does  not  appear  that  it 
is  the  mere  pressure  of  the  air,  as  was  formerly  supposed,  that  pro- 
duces the  crystallization ;  the  air  seems  to  act  as  a  disturbing  force, 
or  perhaps  by  the  introduction  with  it,  of  some  foreign  body,  which 
may  serve  as  a  nucleus. f  A  gentle  waving  motion  does  not  cause  it 
to  congeal.  The  salts  are  crystallized  generally  by  diminishing  the 
quantity  of  the  solvent,  that  is,  by  evaporation,  or  by  conjoining  both, 
diminishing  the  solvent  by  evaporation  and  reducing  the  tem- 
perature ;  or,  when  a  particular  portion  of  a  salt  has  been  sus- 
pended by  the  aid  of  an  elevated  temperature,  a  simple  reduction 
of  temperature  is  sufficient,  without  evaporation.  For,  an  elevated 
temperature  increases  the  power  of  most  solvents.  Common  salt, 
however,  being  dissolved  in  nearly  equal  quantities  by  cold  as  by  hot 

*  That  is  of  particles  of  the  same  kind,  but  these  particles  may  be  chemically, 
either  simple  or  compound. 

t  A  point  or  almost  any  solid  frequently  determines  incipient  crystallization ; 
so  a  jar  or  sudden  vibratory  motion  brings  the  particles  into  such  a  position,  that 
their  polar  attractions  become  effectual,  and  the  negative  pole  of  the  galvanic  series 
produces  crystallization,  while  the  positive  pole  counteracts  it.  Light  also  causes 
camphor  to  crystallize  from  its  alcoholic  solution,  and  it  is  rcdi^sojvcd  in  a  dark  dav 
— Dr.  Ure. 


142  ATTRACTION. 

water,  no  advantage  is  gained  by  the  aid  of  heat,  except  in  speed,  nor 
does  a  reduction  of  temperature  cause  it  to  crystallize.  The  only 
method  in  which  this  can  be  effected,  is  by  diminishing  the  solvent  by 
evaporation.  It  is  found  that  crystallization  is  much  facilitated  by 
supplying  a  nucleus  ;  and  Le  Blanc,  a  Parisian  apothecary,  has  even 
founded  upon  it  a  method  of  obtaining  large  and  beautiful  crystals,  by 
selecting  the  best,  replacing  them  in  the  solution,  and  turning  them 
daily  j  as  the  lower  side  does  not  increase. 

(k.)  An  increase  of  bulk  is  commonly  an  effect  of  crystallization, 
but  sometimes  the  bulk  is  diminished,  as  in  the  case  of  mercury. 
Substances  which  have  been  deposited  from  an  aqueous  solution, 
generally  retain,  intimately  combined,  a  portion  of  water,  which  is 
called  their  water  of  crystallization.  The  efficacy  of  freezing  mix- 
tures is  owing,  in  a  considerable  degree,  to  this  water  of  crystalliza- 
tion, which,  by  becoming  fluid,  absorbs  caloric  ;  when,  with  the  aid 
of  heat,  it  causes  the  salt  to  become  fluid,  the  salt  is  said  to  suffer  the 
aqueous  fusion.  When  it  escapes  spontaneously,  into  the  atmosphere, 
the  salt  is  said  to  effloresce,  for  the  crystalline  form  is  destroyed,  and 
it  falls  into  powder.  When  the  salt  attracts  water  from  the  air,  and 
becomes  more  or  less  fluid,  it  is  said  to  deliquesce*  When  it  splits 
and  crackles  by  heat,  it  is  said  to  decrepitate. 

(I.)  All  bodies,  in  crystallizing,  assume  a  determinate  form.  Thus 
the  crystal  of  alum  is  an  octahedron  ;  that  of  common  salt  a  cube  ; 
of  the  beryl,  a  hexahedral  prism,  &c.  It  must  not  be  understood, 
however,  that  these  forms  are  invariable.  The  same  substance  will 
sometimes  assume  one  form,  sometimes  another,  according  to  cir- 
cumstances. But,  to  this  apparent  caprice  there  is  a  limit,  for  a 
given  substance  will  always  crystallize  in  one  of  a  given  number  of 
forms,  which  are  appropriate  to  it. 

Prisms  and  pyramids  are  among  the  most  common  forms  of  crys- 
tals, but  they  admit  of  great  diversity. 

(m.)  Ml  the  forms  of  crystals  are  reducible  either  by  dissection  or 
by  calculation,  to  six  primitive  forms,  namely,  the  hexahedron,  includ- 
ing the  cube,  parallelopipedon  and  rhomboid  ;  the  regular  octahedron ; 
the  prism  of  six  sides  ;  the  regular  tetrahedron  ;  the  dodecahedron 
with  rhomboidal  faces,  and  the  dodecahedron  with  isosceles  triangu- 
lar faces.  This  very  curious  subject  has  been  developed  by  the  suc- 
cessive labors  of  Rome  de  L'Isle,  Gahn,  Bergman,  Bournon,  and 
Haiiy.  Haiiy  completed  what  Bergman  had  begun,  by  extracting 
the  primitive  form  of  calcareous  spar  in  the  following  manner. 


*  Sometimes  portions  of  the  fluid  from  which  crystals  have  been  precipitated,  are 
lodged  mechanically  between  the  plates,  and  it  may  be  even  a  portion  of  a  fluid  con- 
taining a  different  substance,  if  other  salt*  or  compounds  were  present  in  the  solution. 


ATTRACTION. 


143 


Dr.  Hare,  Fig.  1  to  14. 


>~J — — f     "As  each  of  the   sides  of 

an  hexagonal  prism  of  calca- 
reous spar,  is  bounded  by 
two  edges,  one  at  each  end  of 
the  prism ;  there  are  six  edges 
at  each  end,  and  in  all,  twelve 
edges.  If  to  every  one  of 
the  twelve  edges  a  knife  be 
forcibly  applied,  in  the  direc- 
tion indicated  in  figure  1 ,  one 
of  the  edges,  a  b  c,  a  b  c, 
bounding  each  side,  will  yield 
so  as  to  expose  a  smooth  nat- 
ural facet,  making  an  angle  of 
45°  with  the  adjoining  side.  The  alternate  edges  will  not  split  off 
so  as  to  present  surfaces  corresponding  either  in  smoothness,  or  obli- 
quity, with  those  above  described,  so  that  the  six  facets  will  be  equal- 
ly divided  between  the  two  ends  of  the  prism,  each  having  three  facets 
alternating  with  three  remaining  edges." 

"  If  the  dissection  be  continued,  by  applying  the  knife  in  directions 
parallel  to  the  facets,  finally  a  rhomboid  R  will  be  developed,  which 
exists  not  only  in  the  hexagonal  prism,  but  in  many  other  crystalline 
forms  of  calcareous  spar." 

"All  these  other  forms  are  called  secondary.  The  rhomboid, 
which  is  their  common  nucleus,  or  primitive  form,  is  beautifully  ex- 
emplified in  the  Iceland  spar." 

FIG.  2. 


L 


"  The  same  author  teaches  us  that  a  cu- 
^  bic  crystal  of  fluor  spar,  can  be  split  only 
in  directions  parallel  to  the  faces  of  an  oc- 
tohedral  nucleus,  whose  situation,  relatively 
1  to  the  containing  cube,  is  represented  by 
figure  2." 

"  By  various   dissections,  analogous   to 
those  which  have  been  adduced,  it  is  ren- 
X"J  dered  highly  probable  that  every  crystalli- 

zable  substance  has  an  appropriate  form,  which  it  assumes  in  the  first 
instance,  and  which  is  the  basis  of  all  its  other  forms." 

"  The  nuclei  may  sometimes  be  obtained  by  percussion,  sometimes 
by  heat ;  in  other  cases  by  heat  followed  by  refrigeration." 

"  Although  a  nucleus  cannot  be  extracted  in  every  instance  from 
crystals,  the  existence  in  them  of  primitive  forms,  is  usually  inferred 


144 


ATTRACTION. 


by  analogy.  The  angles  which  the  sides  make  with  each  other,  are 
always  the  same  in  a  nucleus,  however  obtained  ;  and  such  crystals 
are  always  divisible  in  directions  parallel  to  all  their  surfaces,  where- 
as there  are  some  surfaces  of  secondary  forms,  parallel  to  which,  by 
cleavage,  new  facets  cannot  be  obtained." 

"  Haiiy  enumerates  six  primitive  crystalline  forms,  the  parallele- 
piped, (including  the  cube,  rhomboid,  and  four  sided  prism,)  the  reg- 
ular tetrahedron,  regular  octohedron,  hexahedral  prism,  rhombic 
dodecahedron,  and  dodecahedron  with  triangular  faces." 


FIG.  3. — Quadran- 
gular or  four- 
sided  prism. 


FIG.  4. —  Cube.          FIG.  5.— Rhomboid. 


FIG.  6. — Tetrahedron. 


FIG.  7. — Octohedron 


FIG.  8. — Hexangular  or 
six  sided  prism. 


FIG.  9. — Rhombic  dode- 
cahedron. 


ATTRACTION.  i4,j 

FIG.  10. — Dodecahedron  FIG.   11. — Triangular  or 

with  triangular  faces.  three  sided  prism. 


"  The  primitive  forms,  by  a  further  dissection  of  the  octahedron, 
hexangular  prism,  and  dodecahedra,  in  directions,  not  parallel  to  the 
sides,  may  be  reduced  into  three  forms  :  the  tetrahedron,  or  simplest 
solid,  the  triangular  prism,  or  the  most  simple  prism ;  and  the  paral- 
lelopiped,  including  the  cube,  rhomboid,  and  four  sided  prism.  As 
it  is  in  size  only,  that  integrant  atoms  can  be  altered  by  cleavage ;  it 
it  is  inferred  that  if  the  dissections  were  continued  until  the  smallest 
integrant  atom  should  be  developed,  its  form  would  be  the  same  as  that 
of  the  parent  mass.  Hence  also  the  inference  has  arisen,  that  the  only 
forms,  which  belong  to  integrant  atoms,  are  those  above  mentioned." 
It  is  remarkable  that  (the  sphere  and  spheroids  only  being  except- 
ed,)  these  three  forms  are  the  simplest  of  solids.  As  three  lines 
are  the  smallest  number  that  can  include  a  superficies,  so  four  planes 
are  the  smallest  number  that  can  include  a  solid  ;  the  integrant 
molecules  above  named  have  successively,  four,  five,  and  six  faces. 

(n.)  The  actual  or  secondary  forms  are  built  up,  by  the  union  of 
Integrant  particles,  to  produce  the  primitive  form,  and  then  by  the 
addition  of  other  particles,  single  or  in  groups,  upon  the  faces  of  the 
primitive  form . 

(o.)  The  dev elopement  of  these  processes,  constitutes  the  theory  of 
crystallization,  proceeding  according  to  the  laws  of  decrement. 

1.  Parallel  to  the  edges — 2.  Parallel  to  the  diagonal — 3.  Par- 
allel to  a  line  intermediate  between  the  side  and  the  diagonal  ;  or, 
parallel  to  either  of  the  above,  but  proceeding  by  three  in  breadth, 
and  two  in  height,  or  the  reverse,  or  by  such  a  ratio  that  the  relation 
of  height  and  breadth,  in  the  ranges  of  particles,  shall  be  expressed 
by  a  proper  vulgar  fraction  ;  this  supposed  arrangement  of  integrant 
particles  is  called — 4.  Mixed  decrement. 

(p.)  A  minute,  consideration  of  this  subject,  belongs  to  mineralogy 
but  the  following  illustrations  will  render  the  descriptions  of  incre- 
ment and  decrement  intelligible. 

Conversion  of  a  cube  into  a  dodecahedron. 

"  If  a  cube  be  increased  by  layers  of  particles,  applied  to  all  its 
sides,  the  edges  of  the  layers  being  parallel  to  those  of  the  cube,  and 

19 


140 


ATTRACTIONS . 


each  layer  being  made  less  than  that  immediately  preceding  it,  by 
one  row  of  particles  on  each  of  its  edges,  a  dodecahedron,  or  twelve 
sided  solid,  with  rhombic  faces,  will  be  produced." 

FIG.  12. 


"If,  instead  of  diminishing  every  layer  one  row,  on  every  edge,  they 
be  made  less,  at  each  addition,  by  two  rows  on  two  parallel  edges, 
while,  upon  the  other  two  edges,  each  layer  is  made  alternately  the  same 
as  the  preceding,  alternately  less  by  one  row,  a  dodecahedron,  or 
twelve  sided  solid,  with  pentagonal  or  five  sided  faces,  will  be  pro- 
duced." 

FIG.  13. 


ATTRACTION. 


141 


"One  surface  (C)  of  the  cube,  in  each  figure,  is  represented  as  if 
no  addition  were  made  to  it,  in  order  that  the  situation  of  the  nucleus, 
relatively  to  the  pyramids  raised  upon  it,  may  be  understood.  It 
must  be  evident  that  each  rhombus,  R  R  R  R,  in  fig.  12,  and  penta- 
gon, PPPPP,  in  fig.  13,  is  made  up  of  the  surfaces  of  two  adjoin- 
ing pyramids,  built  upon  a  cubic  nucleus." 

;'  The  decrements  may  proceed  only  on  two  sides,  or  a  diminution 
of  two,  three,  or  more  rows  may  take  place  on  all  the  sides ;  yet  in 
either  case,  secondary  crystalline  forms  may  be  built  upon  the  com- 
mon nucleus,  or  primitive  form." 

FIG.  14. — Of  tJiP.   Goniometer,  or  instrument  for  measuring  the  an- 
gles of  crystals. 


"  The  goniometer  is  founded  upon  the  1 5th  proposition  of  Euclid^ 
which  demonstrates  that  the  opposite  angles,  made  by  any  two  lines 
in  crossing  each  other,  are  equal.  Hence  it  follows  that  the  angles 
made  by  the  legs  BB,  BCB,  of  this  instrument,  fig.  14,  above  and 
below  the  pivot  on  which  they  revolve,  are  equal  to  each  other. — 
Consequently,  if  they  be  made  to  close  upon  any  solid  crystalline 
angle,  presented  to  them  at  C,  they  will  comprise  a  similar  angle  on 
the  other  side  of  the  centre  about  which  they  turn.  This  angle  is 
evidently  equivalent  to  that  of  the  crystal,  and  is  ascertained  by  in- 
specting the  semicircle  A,  graduated  into  180  degrees  precisely  in  the 
same  manner  as  a  protractor." 

"The  construction  of  goniometers  is  usually  such  as  to  allow  the 
legs  to  be  detached  from  the  arch,  in  order  to  facilitate  their  appli- 
cation to  crystalline  angles  ;  and  yet,  so  that  they  may  be  reapplied 
to  the  semicircle,  without  deranging  them  from  the  angle  to  whicla 
they  may  have  been  adjusted." 


I4b  ATTRACTION. 

"  The  piece  of  brass,  in  which  the  pivot  is  fastened,  slides  in  a  slit 
in  each  leg,  so  as  to  permit  them  to  be  made  of  the  most  suitable 
length,  on  the  side  on  which  the  crystal  is  applied." 

The  reflective  Goniometer  of  Dr.  Wollaston,  depends  upon  the 
reflection  of  the  rays  of  light  from  the  brilliant  surfaces  of  contigu- 
ous crystalline  plates,  uncovered  by  cleavage,  or  of  natural  surfaces. 
The  pieces  or  crystals  to  be  examined  are  fixed  upon  an  axis  whose 
revolution  carries  around  a  graduated  wheel,  which  measures  the  an- 
gle contained  between  two  contiguous  surfaces,  when  they  have  ar- 
rived successively  in  the  position  to  reflect  an  image  of  the  bar  of  a 
window  or  of  some  other  definite  line.*  This  instrument  is  much 
more  accurate  than  that  of  Carangeau,  used  by  Hauy,  (See  the  fig- 
ure above,)  and  has  corrected  a  number  of  errors,  some  of  which 
were  important. 

Mr.  Daniell  has  contrived  a  method  of  discovering  the  structure  of 
crystals  by  solution.  In  a  mass  of  alum  lying  in  water,  there  will  be 
discovered,  after  some  -time,  upon  its  lower  part  in  high  relief,  both 
octahedral  forms  and  sections  of  octahedra. — Borax  gives  similar 
results.  Even  shapeless  metals,  which  a  peculiar  tendency  to  crys- 
tallization, will  reveal  their  crystalline  forms  by  the  action  of  acid  sol- 
vents; bismuth  exhibiting  with  dilute  nitric  acid,  cubes,  antimony, 
rhomboidal  plates,  and  nickel,  regular  tetrahedra.f 

Very  different  views  of  crystallization  are  taken  by  more  recent 
authors,  among  whom  Mr.  Brooke  f  and  Professor  Mohs§  are  the 
most  distinguished.  Crystalline  forms  that  have  an  intimate  connex- 
ion with  each  other,  are  considered  as  forming  certain  natural  groups 
or  systems  of  crystallization.  They  are  called,  the  tessular  system 
which  comprehends  the  cube,  the  tetrahedron,  the  regular  octahe- 
dron, the  rhombic  dodecahedron,  &c.  ;  the  pyramidical  system,  con- 
taining the  octahedron  with  a  square  base  and  the  right  square  prism  ; 
the  prismatic  system  including  the  rectangular  and  rhombic  octahe- 
dron, and  the  right  rectangular  and  right  rhombic  prisms ;  the  hemi- 
prismatic  system,  embracing  the  right  rhomboidal  and  the  oblique 
rhombic  prisms ;  the  tetarto-prismatic  system  containing  the  oblique 
rhomboidal  prism,  and  the  rhombohedral  system  comprehending  the 
rhombohedron  and  the  regular  hexagonal  prism.  || 

This  complex  system  seems  to  present  no  advantage  to  compen- 
sate for  the  absence  of  the  simplicity  and  perspicuity  which  charac- 
terizes the  system  of  Hauy. 


*  A  more  particular  description  with  a  plate  maybe  found  in  Phillips'  Mineralogy 

t  English  Jour.  Sci   Vol.  I.  p.  24. 

t  Familiar  Introduction  to  Crystallography 

§  Treatise  on  Mineralogy,  translated  by  Mr.  Haidinger. 

it  Turner,  2d  Ed.  p.  555. 


ATTRACTION.  149 

It  is  worthy  of  observation,  that  Professor  Mitscherlich  of  Berlin, 
in  1819,*  discovered  "that  certain  substances  are  capable  of  being 
substituted  for  each  other  in  combination,  without  influencing  the 
form  of  the  compound.  The  neutral  phosphate  and  biphosphate  of 
soda,  have  exactly  the  same  form  as  the  arseniate  and  binarsemate  of 
soda ;  the  phosphate  and  biphosphate  of  ammonia  with  the  arseniate 
and  binarsemate  of  ammonia,  the  biphosphate  and  binarsemate  of 
potash  ;  each  arseniate  has  a  corresponding  phosphate,  possessed  of 
the  same  form  and  containing  the  same  number  of  equivalents  of 
acid,  alkali  and  water,  and  differing  in  nothing  but  in  one's  containing 
arsenic,  and  the  other  phosphoric  acid." 

It  appears  then  that  certain  substances,  when  combined  in  the  same 
manner  with  the  same  body,  are  disposed  to  assume  the  same  crys- 
talline form,  and  this  discovery  has  given  origin  to  the  phrase 
isomorphous  crystals.  The  arseniates  are  isomorphous  with  the 
phosphates ;  the  oxide  of  lead  and  baryta  and  strontia  form  iso- 
morphous salts  with  the  same  acid.  The  isomorphous  crystals  ap- 
pear to  contain  the  same  quantity  of  waterf  of  crystallization,  and 
there  are  many  other  very  curious  circumstances  in  the  constitution 
of  these  bodies,  which  are  too  minute  to  be  introduced  into  this  work, 
but  which  are  thought  to  give  great  support  to  the  atomic  theory  to 
be  mentioned  hereafter. 

THEORY  OF  DR.  WOLLASTON. 

It  has  been  already  remarked,  that  among  solids  bounded  by  plane 
faces,  the  tetrahedron,  the  triangular  prism,  and  the  cube,  are  the 
simplest ;  these  are  the  three  integrant  molecules  of  Hauy,  and  it 
would  seem  that  their  simplicity  and  their  capability  of  being  so  ar- 
ranged as  to  produce,  perhaps,  all  other  solids,  afforded  a  strong  pre- 
sumption in  favour  of  their  being  the  real  integrant  particles  of  bodies. 
But  a  different  view  has  been  taken  of  this  subject  by  Dr.  Wollaston ; 
for  this  reason  among  others,  that  in  "  crystallograpy  we  meet  with 
appearances  which  Haiiy's  theory  but  imperfectly  explains.  A  slice 
of  fluor  spar,  for  instance,  obtained  by  making  two  successive  and 
parallel  sections,  may  be  divided  into  acute  rhomboids  ;  but  these 
are  not  the  primitive  forms  of  the  spar,  because  by  the  removal  of  a 
tetrahedron  from  each  extremity  of  the  rhomboid,  an  octohedron  is 
obtained.  Thus,  as  the  whole  mass  of  fluor  may  be  divided  into  te- 
trahedra  and  octohedra,  it  becomes  a  question  which  of  these  forms 


*  Ann.  de  Chimie  and  de  Physique,  Vol.  XIV,  p.  172,  XIX,  p.  850,  and  XXIV, 
pp  264  and  355,  Turner. 

t  And  when  the  quantity  of  water  is  different,  the  crystals  assume  a  different 
form.— Turner. 


150 


ATTRACTION. 


is  to  be  called  primitive,  especially  as  neither  of 
them  can  fill  space  without  leaving  vacuities, 
nor  can  they  produce  any  arrangement  suffi- 
ciently stable  to  form  the  basis  of  a  permanent 
crystal." 

"  To  obviate  this  incongruity,  Dr.  Wollaston 
(Phil.  Trans.  1813,)  has  very  ingeniously  pro- 
posed to  consider  the  primitive  particles  as 
spheres,  which,  by  mutual  attraction,  have  as- 
sumed that  arrangement  which  brings  them  as 
near  as  possible  to  each  other.  When  a  num- 
ber of  similar  balls  are  pressed  together,  in  the  same  plain,  they  form 
equilateral  triangles,  with  each  other  ;  and 
if  balls  so  placed  were  cemented  together, 
and  afterwards  broken  asunder,  the  straight 
lines  in  which  they  would  be  disposed  to 
separate,  would  form  angles  of  60°  with 
each  other.  A  single  ball  placed  any  where  on  this  stratum,  would 
touch  three  of  the  lower  balls,  and  die  planes  touching  their  surfaces 
would  then  include  a  regular  tetrahedron.  A  square  of 
four  balls,  with  a  single  ball  resting  upon  the  centre  of 
each  surface,  would  form  an  octohedron  ;  and  upon  ap- 
plying two  other  balls  at  opposite  sides  of  this  octohe- 
dron, the  group  will  represent  the  acute  rhomboid. 
Thus  the  difficulty  of  the  primitive  form  of  fluor,  above  alluded  to,  is 
done  away,  by  assuming  a  sphere  as  the  ultimate  molecula.  By  ob- 
late and  oblong  spheroids,  other  forms  may  be  obtained."* 


Dr.  Wollaston  has  demonstrated,  geometrically,  that  by  assorting 
spheres  and  spheroids  in  particular  groups  and  modes,  all  the  solids 
of  crystals  may  be  constructed.  The  cannon  balls  in  an  arsenal,  are 
often  arranged  in  such  a  manner  as  to  illustrate  this  subject.  One 
group  forms  a  square  and  another  a  triangle,  and  by  piling  them 


*  Brande,  quoted  by  Hare. 


ATTRACTION.  151 

they  become  pyramids,  shewing  half  a  tetrahedron,  half  an  octohe- 
dron,  &tc.  which  would  be  completed,  by  continuing  the  group  down- 
ward, in  the  same  form.  The  marbles  used  for  play,  by  children, 
may  be  made  use  of  for  similar  illustrations.  But  it  is  obvious  that 
the  truth  of  this  view,  beautiful  and  probable  as  it  is,  cannot  be  de- 
monstrated, nor  is  it  perhaps  inconsistent  with  that  of  Haiiy ;  for  if 
the  ultimate  integrant  particles  of  bodies  are  spheres  or  spheroids  ;  as 
they  may,  by  the  supposition,  be  grouped  so  as  to  produce  Hauy's  in- 
tegrant molecules,  and  these  may  be  the  last  term  of  mechanical 
analysis,  although  the  ultimate  particles  of  which  they  are  composed, 
may  be  spheres  ;  and  when  they  are  inconceivably  small,  there  will 
be  no  appreciable  difference  between  the  plane  and  curved  faces. 
Indeed,  in  Hauy's  theory,  the  passage  by  increment  and  decrement, 
is  supposed  to  be  by  particles  so  minute,  that  the  steps  cannot  be  or- 
dinarily perceived,  although  the  imperfection  of  the  process  some- 
times renders  them  more  or  less  obvious.* 

5.  CHEMICAL  ATTRACTION  OR  AFFINITY. 

(a.)  It  is  exclusively,  a  corpuscular  power. 

(6.)  Its  three  principal  characteristics,  are  :  it  is  exerted  at  insen- 
sible distances ;  between  particles  only ;  and  those  particles  are  al- 
ways heterogeneous. 

(c.)  Its  effects  are,  a  change  of  properties  more  or  less  complete  : 
it  is  unlike  cohesion,  which  induces  no  change  of  properties,  but 
merely  of  bulk  or  form. 

(d.)  The  change  of  properties,  in  the  cases  where  weak  affinities 
are  exerted,  is  often  slight ;  giving  in  many  instances  only  the  mod- 
ified properties  of  the  parent  substances  ;  as  examples,  we  can  men- 
tion watery  solutions  generally,  as  of  salts,  gum  and  sugar,  and  often 
alcoholic  solutions,  as  of  resins ;  and  among  fluids,  alcohol  and  water, 
and  water  and  acids ;  the  union  in  such  cases,  is  quiet,  and  attend- 
ed with  no  remarkable  appearances. 

(e.)  But  the  union  is  permanent  and  cannot  be  destroyed  by  mechan- 
ical means.  Solutions  of  salts,  sugar,  gum,  and  alcohol,  in  water,  are 
instances  in  point ;  they  are  not  decomposed  by  repose,  by  agitation 
or  by  filtration,  thus  proving  that  the  union  is  not  merely  mechanical. 

(f.)  This  class  of  compounds  should  be  considered  as  midway  be- 
tween mere  aggregation  and  energetic  chemical  combination  ; — The 
union  is  chemical,  inasmuch  as  it  is  not  subverted  by  mechanical 
means  ;  but  these  compounds  partake  of  the  nature  of  aggregates,  in- 
asmuch as  they  present  the  mitigated  properties  of  the  parent  sub- 
stance and  no  new  properties. 

*  Mr.  Daniel,  in  a  paper  in  the  Eng.  Jour,  of  Science,  Vol.  I,  p.  24,  has  with  great 
ability,  illustrated  Dr.  Wollaston's  theory ;  but  the  limits  of  this  work  do  not  allovv 
ns  to  go  farther  into  these  metaphysics  of  crystallization  ;  a  subject  which  is  per* 
Jiap<?  more  closely  allied  to  mechanical  than  to  chemical  philosophy. 


152  ATTRACTION. 

(g.)  Mere  mechanical  mixtures  are  separated  by  mechanical  means  ; 
muddy  water  becomes  clear  by  filtration  and  by  repose,  which  have 
no  effect  upon  salt  water. 

(h.)  Energetic  chemical  action  produces  an  entire  change  of  prop- 
erties. Oxygen  and  hydrogen  have  no  resemblance  to  water  or  to 
each  other  ;  nitric  acid  and  potassa  none  to  salt  petre  ;  muriatic  acid 
and  soda  none  to  common  salt ;  potassium  and  oxygen  none  to  po- 
tassa and  so  on,  in  a  thousand  cases  more.  Inert  substances  pro- 
duce active  compounds,  as  in  sulphuric  acid;  active  principles  inert 
compounds  as  in  sulphate  of  pot?ssa ;  compounds  containing  an  en- 
ergetic principle  or  principles,  retain  a  degree  of  activity,  sometimes 
great,  as  nitrate  of  silver  and  many  oilier  metallic  salts,  and  arseniate 
of  potassa  ;  inert  principles  produce  inert  compounds,  as  in  borate  of 
magnesia,  and  in  a  word,  there  is  g''eat  variety  in  the  results,  so  that 
they  cannot  be  predicted,  and  can  be  learned  from  experiment  only. 

(i.)  Colors  are  produced,  and  different  colors  by  different  propor- 
tions of  the  same  materials.  The  metallic  oxides  and  salts,  red  lead, 
oxide  of  mercury,  the  chromates  of  lead,  natural  and  artificial,  and 
the  two  sulphwets  of  mercury  and  of  arsenic,  are  examples. 

Jj.)  Colors  are  destroyed. — Chlorine  destroys  nearly  all  colors, 
the  sulphurous  acid  many. 

(k.)  The  specific  gravity  is  changed,  and  generally  increased. — 
Compounds  of  ammonia  and  the  acid  gases  are  precipitated  in  the 
form  of  solid  sails  ;  but  some  of  the  metallic  alloys  are  lighter  than 
the  mean  specific  gravity  of  the  metals  combined  ;*  and  some  gaseous 
combinations  form  other  gaseous  compounds  that  are  lighter,  but  in 
general  aeriform  bodies  by  combining,  undergo  condensation.^ 

(/.)  Temperature,  or  sensible  heat,  is  changed. — It  is  increased,  as 
when  alcohol  and  water,  sulphuric  acid  and  water,  oxygen  and  com- 
bustibles, sulphur  and  metals,  iodine  and  phosphorus,  are  united. 

It  is  diminished,  as  by  solution  and  by  all  freezing  mixtures. 

(m.)   The  form  of  bodies  is  changed. 

Solids  become  fluid,  as  in  the  freezing  mixtures ;  also  Glauber's 
salts  and  nitrate  of  ammonia  rubbed  together. —  Webster. 

Fluids  become  solid,  as  water  in  slaked  lime,  and  in  nearly  all 
crystals. 

Solution  of  strong  muriate  of  lime,  decomposed  by  strong  sulphu- 
ric acid  is  precipitated  solid ;  most  acids  by  combining  writh  different 
bases  produce  solids,  provided  water  is  removed  by  evaporation. 

Gases  become  liquid. — Oxygen  and  hydrogen  form  water. 


*  The  constituent  particles  may  have  approximated  and  the  integrant  particles 
receded,  so  that  the  fact  involves  no  impossibility. 

t  In  olefiant  gas,  the  elements  in  a  state  of  freedom  would  occupy  four  volumes1 
instead  of  one. 


ATTRACTION.  153 

Gases  become  solid. — Acid  gases  and  ammonia  precipitate  solid 
salts,  (vide  k.) 

Solids  become  gas. — Several  ammoniaeal  salts,  properly  decom- 
posed, are  converted  into  aeriform  bodies  ;  this  is  true,  particularly  of 
the  nitrate  and  muriate  of  ammonia. 

Fluids  become  gas. — Water  decomposed  by  galvanism  with  gold 
or  platina  wires  affords  oxygen  and  hydrogen  gases  in  mixture.* 

(n.)  Jl  very  minute  division  of  matter  is  effected  by  chemical  union. 
It  is  much  more  minute  than  any  mechanical  means  can  produce  ;  ni- 
trate of  silver  discovers  the  slightest  trace  of  muriatic  acid :  so  am- 
monia detects  any  salt  of  copper ;  hydriodic  acid  platinum ;  recent 
muriate  of  tin  and  green  sulphate  of  iron  discover  gold. 

(o.)  Cohesion  resists  chemical  action. — Therefore  as  a  prelim- 
inary it  is  diminished,  by  the  mechanical  operations  of  pounding, 
rasping,  grinding,  &tc.  and  by  previous  chemical  operations,  as  when 
caustic  potash  is  fused  with  refractory  gems  and  stones,  to  prepare 
them  for  solution  in  acids.  Marble  in  lumps,  dissolves  slowly  in  acids, 
but  in  powder  rapidly, — so  of  salt,  sugar,  &-c. 

(p.)  Affinity  is  not  universal. — Water  does  not  dissolve  siliceous 
sand,  nor  resins,  nor  oil,  nor  clay ;  these  bodies  may  be  mixed  with 
water  by  mechanical  agitation,  but  they  will^separate  again  by  repose, 
or  by  filtration  or  other  mechanical  means. 

(q.)  No  body,  elementary  or  compound,  is  without  affinities. — Sili- 
ceous sand  unaffected  by  water,  is  dissolved  by  caustic  potash ;  resin 
by  alcohol,  oil  by  alkali,  common  clay,  in  part,  pure  argil  entirely,  by 
sulphuric  acid. 

(r.)  Solution  is  only  a  particular  case  or  mode  of  chemical  action 
and  union. — It  takes  place  generally,  between  solids  and  fluids  ;  but 
is  also  predicable  of  the  other  forms  of  matter  ;  gases  dissolve  solids 
and  fluids,  and  these  in  turn  absorb  gases. 

(s.)  Solution  is  generally  promoted  by  heat. — In  the  cold,  4oz. 
of  water  do  not  dissolve  3oz.  of  sulphate  of  soda,  but  heat  enables 
the  whole  to  be  readily  dissolved. — Henry. 

(t.)  The  solubility  of  different  substances,  in  the  same  fluid,  is  very 
different. — Joz.  sulphate  of  ammonia,  Joz.  sulphate  of  soda,  TVoz. 
of  sulphate  of  potash,  and  j^  of  sulphate  of  lime,  are  dissolved  in 
loz.  distilled  water. — Id. 

(u.)  Heat  generally  promotes  chemical  action;  as  is  commonly  said, 
and  in  most  cases  truly,  by  diminishing  the  power  of  cohesion,  as  is 
seen  in  the  solutions  of  solids  ;  but  this  explanation  would  hardly  apply 
to  the  explosion  of  gunpowder,  and  of  fulminating  powders.  Some- 
times cold  brings  on  chemical  action  ;  sea  water,  containing  muriate 

*  Many  important  chemical  events  depend  on  condensation  or  evolution  of  gases ; 
explosions  are  often  produced  by  the  latter. 

20 


154  ATTRACTION. 

of  soda,  and  sulphate  of  magnesia,  is  said  to  undergo  double  decom- 
position, at  the  freezing  temperature,  producing  sulphate  of  soda,  and 
muriate  of  magnesia.*  It  cannot  be  doubted,  that  electric  and  gal- 
vanic agencies  are  frequently  developed  by  heat,  and  that  thus  chem- 
ical action  is  often  induced. 

(v.)  Jl  modified  degree  of  heat  is  necessary. — Red  precipitate  is 
formed  at  or  near  the  boiling  heat  of  mercury,  but  it  is  decomposed  by 
ignition,  and  both  its  oxygen  and  metal  are  recovered. 

(w.)  Chemical  action  is  often  brought  on  by  mechanical  means. — 
Several  of  the  fulminating  powders,  and  the  mixtures  of  the  chlo- 
rate of  potash  and  combustibles,  explode  by  a  blow,  by  friction,  and 
pressure  ;  which  favor,  at  once,  the  approximation  of  the  particles 
within  the  sphere  of  attraction,  and  the  developement  of  heat  which 
favors  the  chemical  action. 

(a?.)  JVo  approximation,  short  of  imperceptible  distance,  will  bring 
on  chemical  action. — The  negative  is  established  by  the  approxima- 
tion of  any  kind  of  matter  towards  any  other  for  which  it  has  an 
affinity ;  as  for  instance,  a  drop  of  nitric  acid  on  a  glass  plate,  will  be 
indifferent  to  silver  or  copper  filings  pushed  near  to  it,  but  the  action 
commences  when  apparent  contact  is  established.  When  sulphur 
and  mercury  are  in  apparent  contact,  there  is  no  action,  but  it  is 
brought  on  by  rubbing  them  together.  Sulphuric  acid  will  run  to 
the  bottom  of  alcohol,  and  produce  action  only  at  the  touching  sur- 
faces, but  it  is  quickly  brought  on,  in  the  entire  mass,  by  agitation. 
Agitation  of  fluids  and  solids,  to  make  them  mingle  quickly,  pro- 
motes their  action,  as  in  the  case  of  common  salt  and  water. 

(y.)  Even  apparent  contact  is  often  insufficient,  and  solution  be- 
comes necessary.  Hence,  the  old  maxim,  "  corpora  non  agunt  nisi 
sint  soluta."  Tartaric  acid  and  carbonate  of  soda,  dry  quicklime  and 
dry  muriate  of  ammonia,  dry  nitrate  of  copper,  wrapped  in  tinfoil — 
in  each  of  these  cases  there  is  no  action  till  moisture  is  supplied, 
when  it  comes  on  vigorously. 

(z.)  Bodies  having  no  affinity  are  sometimes  brought  to  unite  by  a  third 
body. — Oil  and  water,  by  the  intermedium  of  caustic  alkali,  form  soap. 

(AA.)  THE  FORCE  OF  AFFINITY  is  DIFFERENT  BETWEEN  DIF- 
FERENT BODIES. 

Were  it  otherwise,  there  wrould  be  no  decompositions,  except  by 
the  effect  of  the  imponderable  agents. 

(BB.)  ELECTIVE  AFFINITY  is  THE  FIGURATIVE  EXPRESSION  OF 

THE  PREFERENCE  WHICH  ONE  BODY  IS  SUPPOSED  TO  MANIFEST 
FOR  ANOTHER,  TO  THE  EXCLUSION  OF  A  THIRD. 

The  alcoholic  solution  of  camphor  is  precipitated  by  water,  which 
unites  with  the  alcohol,  and  the  camphor  may  be  redissolved  by  the 
addition  of  more  alcohol. 

*  Aikiu's  Diet.  Vol.  II.  pp.  389,  and  779. 


ATTRACTION.  155 

The  acetate  of  lead  is  decomposed  by  sulphuric  acid ;  the  nitrate 
of  silver,  by  copper  ;  nitrate  of  copper,  by  iron ;  nitrate  of  mercury, 
by  copper ;  muriate  of  soda,  by  sulphuric  acid  ;  and  so  in  instances 
innumerable.  In  all  these  cases,  except  the  first,  there  is  a  new 
salt  formed  by  the  addition  of  the  decomposing  body,  the  acid  or 
base  of  the  preceding  salt  being  liberated. 

(CC.)  In  such  cases,  therefore,  a  compound  of  two  principles  is  de- 
composed by  a  third,  which  unites  with  one,  and  excludes  the  other, 
which  may  be  thus  illustrated;  A+B=C.  D  unites  with  A,  and 
forms  the  compound  A+D,  or  with  B,  and  forms  the  compound 
D-j-B,  B  in  the  first  case,  and  A  in  the  second,  being  excluded. 
If  any  solid  appears,  it  is  called  the  precipitate,  and  the  decomposing 
body,  the  precipitant ;  the  fluid  is  called  the  solution. 

(dd.)  In  some  cases,  a  weaker  affinity  is  compensated  by  an  in- 
creased quantity  of  the  feebler  ingredient. — Muriate  of  soda  2, 
oxide  of  lead  1 ,  there  is  no  effect  in  twenty  four  hours ;  but  with 
muriate  of  soda  1,  and  oxide  of  lead  3  or  4,  decomposition  follows  in 
twenty  four  hours,  and  muriate  of  lead  is  formed,  and  soda,  or  its  sub- 
carbonate,  evolved  ;  this  fact  is  the  foundation  of  the  manufacture  of 
soda  from  common  salt.  The  solution  of  sulphate  of  copper  is  blue, 
but  if  the  muriatic  acid  is  added  largely,  the  color  changes  to  green, 
indicating  a  decomposition,  and  the  production  of  a  muriate  of  cop- 
per. 

(EE.)  DOUBLE  ELECTIVE  AFFINITY,  is  WHERE  TWO  COMPOUNDS, 

EACH  CONSISTING  OF  TWO  INGREDIENTS,  ARE  DECOMPOSED,  FORM- 
ING TWO  NEW  COMPOUNDS. — A,  composed  of  B+C,  is  mixed  with 
D,  composed  of  E+F;  the  result  may  be,  B+E,  or  B-fF,  or 
C-f  E,  or  C  +  F.  Important  decompositions,  otherwise  unattaina- 
ble, are  often  effected  in  this  manner. 

(FF.)  DECOMPOSITIONS  STILL  MORE  COMPLEX,  INVOLVING  THE 

ACTION  OF  SEVERAL  AGENTS,  EACH  CONSITING  OF  TWO  OR  MORE 
PRINCIPLES,  MAY  PRODUCE  SEVERAL  DECOMPOSITIONS,  AND  SEVE- 
RAL NEW  COMPOUNDS. — Many  of  the  processes  in  the  animal  and 
vegetable  economy,  are  of  this  description,  and  some  among  minerals. 

(GG.)  Extraneous  circumstances  and  forces  influence  chemical  ac- 
tion, among  which  the  chief  are  quantity,  cohesion,  insolubility,  grav- 
ity, elasticity,  efflorescence,  temperature,  mechanical  pressure,  and 
electricity. 

1 .  Quantity  of  matter  exerts  an  important  influence  on  chemical 
decompositions.  This  is  a  well  known  practical  fact.  In  dissolv- 
ing a  salt  in  water,  the  first  portions  added,  are  more  readily  dissolv- 
ed than  subsequent  ones,  and  the  energy  of  attraction*  diminishes  as 
we  approach  the  point  of  saturation. 

*  Or  is  it  mechanical  obstruction  that  retards  the  solution ;  the  degree  of  affinity 
remaining  the  same  ?— (Communicated.} 


156  ATTRACTION. 

So,  in  decomposing  compound  bodies,  either  by  affinity,  or  heat, 
the  last  portions  are  sometimes  separated  with  much  greater  diffi- 
culty than  the  first ;  thus  the  black  oxide  of  manganese  easily  gives 
up  one  proportion  of  oxygen  by  a  red  heat,  but  no  degree  of  heat 
can  expel  the  whole.  In  the  same  manner,  the  last  portions  of  car- 
bonic acid  are  expelled  from  carbonate  of  lime,  with  great  difficulty 
— the  first  with  ease. 

To  effect  complete  decompositions,  also,  it  is  sometimes  necessa- 
ry to  employ  large  quantities  of  the  decomposing  substances,  as  in 
precipitating  a  metallic  oxide  from  its  union  with  an  acid,  and  in  de- 
composing various  salts  by  acids,  as  the  nitrate  of  potash  by  sulphu- 
ric acid. 

Partial  decompositions  are  produced  also  by  the  exertion  of  a 
weaker  affinity,  if  it  is  aided  by  a  larger  quantity  of  matter,  as  in  the 
case  of  muriate  of  soda  and  oxide  of  lead.  From  these,  and  other 
similar  facts,  the  distinguished  chemist  Berthollet  drew  the  conclu- 
sion "  that  affinity  is  modified  by  quantity  of  matter,  or  that  the 
chemical  action  of  a  body  is  exerted  in  the  ratio  of  its  affinity  and 
quantity  of  matter,  and  he  endeavored  to  establish  it  as  a  law,  apply- 
ing to  all  cases  of  chemical  combination." — (Murray.}  He  sup- 
posed also  that  "  wThen  two  substances  are  in  competition  to  com- 
bine with  a  third,  each  of  them  obtains  a  degree  of  saturation  pro- 
portionate to  its  affinity  multiplied  by  its  quantity  ;  a  product  which 
he  denominates  mass." — (Ure.) 

Berthollet  supposed  that  the  tables  of  affinity  expressed  merely 
the  actual  order  of  decomposition,  as  influenced,  not  only  by  affinity, 
but  by  quantity  of  matter,  and  many  other  circumstances,  and  that 
there  was  no  such  thing  as  a  settled  force  of  affinity,  between  differ- 
ent substances.  Berthollet  contended  also,  that  in  proportion  as  it 
requires  more  of  a  particular  base  to  saturate  a  given  acid,  the  less 
is  the  affinity  between  that  acid  and  the  base. 

But  we  will  not  occupy  time  with  views,  which  however  ingenious 
and  ably  supported,  appear  not  to  be  universally  tenable.  Many  of 
tire  facts  adduced  in  support  of  them,  can  be  explained  in  other 
ways,  and  the  well  established  doctrine  of  definite  proportions  could 
not  be  true,  were  there  no  exact  force  of  affinity,  independent  of 
quantity  of  matter.  Still,  quantity  of  matter  does  undoubtedly  ope- 
rate in  many  cases,  to  a  certain  extent,  and  "  although  incompetent 
to  counteract  direct  and  strong  affinities,  or  to  affect  the  combination 
of  bodies  which  are  disposed  to  unite  in  definite  proportions,  its  in- 
fluence may  be  clearly  traced  in  a  number  of  instances,  where  it 
modifies  weaker  attractions,  and  perhaps  decides  the  result,  when 
opposite  affinities  are  nearly  balanced."* — (Murray.) 

*  See  Prof.  E.  Mitchell's  paper  on  the  effect  of  quantity.— Jim.  Jour.  Vol.  XVI. 
p.  234. 


ATTRACTION,  157 

2.  Cohesion. — It  has  been  already  stated  that  this  power  is  the  im- 
mediate antagonist  of  chemical  action,  which  rarely  takes  place  till  it  is 
overcome.     Hence  the  great  advantage  of  solution  and  fusion,  which 
are  the  most  common  means  of  inducing  chemical  action.     In  a  few 
cases,  the  energy  of  attraction  is  so  great  as  to  overcome  the  cohe- 
sion of  two  solids,  and  cause  them  to  unite,  and  to  become  fluid  in 
the  act  of  combining.     Muriate  of  lime  and  snow,  and  caustic  fixed 
alkalies  and  snow  are  examples.     Even  fluids  may  have  their  ener- 
gy exalted  by  increased  temperature,  as  is  the  case  with  nitric  acid  and 
alcohol  or  oils,  and  with  sulphuric  acid  and  water  :*  if  these  fluids  are 
hot  it  is  scarcely  safe  to  mingle  them  in  any  considerable  quantity. 
Heat  always  promotes  chemical  combination,  when  cohesion  is  an 
obstacle,  and  often,  it  is  sufficient  that  one  of  the  substances  should 
be  fluid.     Mechanical  division  favors  chemical  action,  principally  by 
increasing  the  surface.      Cohesion  resulting  from  chemical  action 
often  modifies  the  results  of  experiments.     A  mixture  of  sulphuric 
and  muriatic  acids,  with  a  solution  of  baryta,  will  result  in  the  form- 
ation of  sulphate  of  barytes ;  in  part,  no  doubt,  on  account  of  its  in- 
solubility, but  the  effect  must  depend  also  upon  a  superior  affinity. 

3.  Insolubility. — This  depends  upon  cohesion,  and  has  reference 
to  the  solvent  power  of  the  liquid  in  which  the  cohesive  power  is  ex- 
erted.    It  removes  the  body,  newly  formed  from  the  sphere  of  action, 
and  thus  leaves  the  remaining  principles  free  to  act  upon  each  other. 

4.  Gravity. — So  far  as  there  is  a  great  difference  in  the  gravity 
of  bodies  that  are  mixed,  it  goes  to  retard  chemical  action.     Thus, 
salt  at  the  bottom  of  water  dissolves  much  more  slowly  and  unequal- 
ly than  if  it  is  agitated  ;  and  if  allowed  to  remain  quiet,  the  solution 
will  be  most  dense  at  bottom,  and  the  least  so  at  top.     If  metals  of 
widely  different  specific  gravity  are  melted  together  to  form  an  alloy, 
a  larger  proportion  of  the  heaviest  metal  will  be  found  at  the  bottom, 
and  agitation  is  necessary,  in  order  to  bring  the  particles  into  prox- 
imity, so  that  the  union  may  be  effected. 

5.  Elasticity. — This  power,  under  different  circumstances,  both  op- 
poses and  favors  chemical  action.     In  general,  gases  are  not  prone  to 
combine,  because  their  ponderable  particles  are  too  far  removed  from 
each  other  by  the  caloric,  with  which  they  are  united.     Thus  oxygen 
and  hydrogen  gases  may  be  retained  in  mixture,  without  combining : 
till  flame  causes  them  to  unite  explosively.     Ammonia  and  the  acid 
gases  unite  readily,  and  even  precipitate  solid  matter,  and  one  gas 

*  Dr.  Turner  remarks,  (Chem.  2d  Ed.  p.  137,)  that  "  fluids  commonly  act  upon 
each  other  as  energetically  at  low  temperatures,  or  at  a  temperature  just  sufficient 
to  cause  perfect  liquefaction,  as  when  their  cohesive  power  is  still  farther  diminished 
by  caloric."  The  familiar  instances  mentioned  in  the  text  show  that  this  remark 
needs  to  be  qualified. 


158  ATTRACTION. 

in  the  nascent  state,  will  unite  with  another  already  in  the  elastic 
form  ;  thus  hydrogen  unites  with  nitrogen,  to  form  ammonia,  and 
both  these  gases,  evolved  from  putrefaction,  combine  in  their  nascent 
state,  and  form  the  same  body. 

Mechanical  force  favors  the  combination  of  gases  with  each  other, 
and  with  fluids ;  oxygen  and  hydrogen  can  be  made  to  combine  by  sud- 
den and  violent  pressure  ;*  and  pressure,  cold  and  agitation  are  the  usual 
means  of  impregnating  fluids  with  gases,  as  in  the  case  of  soda  water. 

Elasticity  favors  decomposition.  When  one  constituent  of  a  body 
is  prone  to  assume  the  aerial  state,  in  general  that  body  is  more  easily 
decomposed,  both  by  heat  and  by  affinity,  than  if  both  ingredients  were 
fixed.  This  is  the  case  with  the  carbonates,  and  with  water  contain- 
ed in  crystals,  and  other  combinations ;  and  even  potassium  is  driven  off 
by  its  superior  volatility,  at  an  intense  heat,  when  the  alkali  contain- 
ing it  is  brought  into  contact  with  highly  ignited  iron.  Many  instan- 
ces in  illustration  of  these  views  will  occur  as  we  proceed. 

6.  Efflorescence. — This  is  a  circumstance  of  no  great  importance, 
but  it  sometimes  favors- chemical  action,  by  withdrawing  a  salt  that  has 
been  formed,  from  the  field  of  action,  and  in  this  manner  leaving  the 
remaining  ingredients  free  to  act  again.     Thus  in  the  country  around 
the  natron  lakes  in  Egypt,  muriate  of  soda  and  carbonate  of  lime  mu- 
tually decompose  each  other,  and  the  carbonate  of  soda  crawls  up  in 
crystals  upon  the  grass  and  other  bodies  accidentally  present.     A 
similar  effect  I  have  often  observed  upon  common  plaster,  made 
with  sea  sand  containing  muriate  of  soda,  which  undergoes  decompo- 
sition, with  the  carbonate  of  lime,  and  forms  by  efflorescence  a  plu- 
verulent  carbonate  of  soda  appearing  like  a  fine  snow  upon  the  walls. 

7.  Temperature. — The  relation  of  bodies  to  heat  is  of  the  utmost 
importance  with  respect  to  chemical  action ;  but  the  principal  facts 
have  been  already  adverted  to,  under  other  heads,  and  will  be  con- 
stantly illustrated  in  our  whole  progress  through  the  science  of  chem- 
istry.    In  general,  however,  it  may  be  said  that  there  are  few  chemi- 
cal events  which  are  not  either  brought  on  by  change  of  tempera- 
ture, or  which  do  not  induce  a  change  in  that  particular. 

8.  Pressure,  is  an  important  auxiliary  to  chemical  action.     It  often 
determines  its  commencement,  as  in  the  fulminating  powders,  and  the 
mixtures  of  the  chlorate  of  potassa  with  combustibles.     It  appears  to 
operate  both  by  causing  approximation  of  particles,  and  by  inducing 
augmentation  of  temperature.     Its  agency  on  elastic  fluids  in  relation 
to  each  other,  and  in  relation  to  them  and  gross  fluids,  and  even  to 
solids,  is  not  less  important.     But  most  of  the  leading  facts  have 
been  mentioned  already,  or  will  be  mentioned  hereafter. 


Probably  in  consequence  of  the  heat  evolved. 


ATTRACTION,  [»y 

9.  Galvanic  Electricity,  is  one  of  the  most  important  of  these 
causes.  Its  general  powers  have  been  already  sketched,  and  it  will 
be  more  fully  developed  in  the  sequel. 

(HH.)  LIMITATIONS  OF  COMBINATION. 

1.  Unlimited  on  both  sides. — Water  and  alcohol,  and  water  and 
the  strong  acids  are  examples  ;  the  smallest  quantity  of  the  one  may 
be  combined  with  the  largest  of  the  other,  and  the  reverse ;  a  drop 
of  water  with  an  ocean  of  alcohol ;  a  drop  of  alcohol  with  an  ocean 
of  water. 

2.  Limited  on  one  side. — In  the  case  of  water  and  saline  sub- 
stances, the  smallest  portion  of  salt  may  combine  with  the  largest 
quantity  of  water,  but  if  we  continue  to  add  the  salt,  the  water  be- 
comes saturated,  and  any  additional  quantity  will  remain  on  the  bot- 
tom undissolved.     Alcohol  with  camphor  and  resins,  is  governed  by 
a  similar  law. 

3.  Limited  on  both  sides  to  one  proportion.     Hydrogen  gas  3  vol- 
umes, and  nitrogen  gas  1 ,  unite  to  form  ammonia.     Chlorine  gas  and 
hydrogen  gas,  in  equal  volumes,  form  muriatic  acid. 

4.  Limited  to  one  of  several  proportions. — Nitrogen  and  oxygen 
unite  in  the  several  proportions  to  form  nitrous  oxide,  nitric  oxide, 
and  the  nitrous  and  nitric  acids. 

Hydrogen  2  volumes  +  oxygen  1,  form  water. 

Hydrogen  2       "  "        2,  form  deutoxide  of  hydrogen. 

(I  I.)  THE  PROPORTIONS  IN  WHICH  BODIES  COMBINE  ARE  GOV- 
ERNED BY  FIXED  LAWS. 

Before  proceeding  to  illustrate  this  proposition,  we  must  observe, 
that  there  is  a  vast  variety  in  different  cases,  in  the  force  of  chemical 
attraction.  Sulphate  of  barytes  is  hardly  decomposed  by  any  single 
agent,  and  other  bodies  of  whose  compound  character  we  cannot 
doubt,  as  fluoric  acid,  have  not  been  decomposed  at  all ;  because 
the  force  of  affinity  is  so  strong  between  their  principles,  that  nothing 
has  been  able  hitherto  to  overcome  it.  But  in  other  cases,  the  affin- 
ity is  so  slight  that  it  is  subverted  by  small  variations  of  temperature, 
or  by  very  feeble  attractions ;  as  when  alcohol  is  separated  from  wa- 
ter by  distillation,  or  salts  crystallized  by  the  simple  cooling  of  their 
saturated  solutions ;  so,  alcohol  holding  camphor  in  solution,  gives  it 
up  readily  when  water  is  introduced,  which  attracts  the  alcohol. 

(kk.)  Properties  of  simple  solutions,  and  of  other  feeble  combina- 
tions.— The  properties  are,  not  at  all,  or  but  little  changed,  and  often 
in  no  other  way,  than  to  produce  modified  qualities,  depending  on 
those  of  the  parent  substances,  and  on  their  proportions.  Solutions  of 
gum,  sugar,  salts,  and  acids  in  water  ;  and  of  resins,  essential  oils  and 
camphor  in  alcohol  are  familiar  examples.  Such  cases  resemble 
mixtures,  in  as  much  as  there  is  little  or  no  change  in  the  properties 
of  the  principles ;  and  we  readily  perceive,  either  by  our  senses  or  by 


160  ATTRACTION, 

the  application  of  easy  tests,  the  predominance  of  the  one  or  of  the 
other,  or  their  equality.  On  the  other  hand,  they  resemble  chemical 
combinations,  because  the  principles  cannot  be  separated  by  any  me- 
chanical means ;  neither  repose,  agitation  or  filtration,  has  any  effect; 
and  decomposition,  when  one  ingredient  is  sensibly  more  volatile  than 
the  other,  is  effected  by  evaporation  or  distillation,  or  in  other  cases, 
by  the  intervention  of  an  affinity  ;  or  by  cold. 

(II.)  This  class  of  compounds  appears  to  be  intermediate  between  a 
mechanical  and  chemical  condition. — We  seem  to  need  a  division  of 
this  kind  ;  it  would  free  us  from  embarrassment,  with  respect  to  the 
universality  of  definite  proportions,  and  it  is  more  reasonable  to  admit 
such  a  division  than  to  suppose  the  existence  of  innumerable  mix- 
tures of  different  combinations,  in  definite  proportions,  of  such  things 
as  sugar  and  water,  alcohol  and  water,  &c. 

As  no  single  word  expresses  their  peculiarities,  and  for  want  of  a 
better  designation,  they  may  be  called  chemico-mechanical,  or  me- 
chanico-chemical  compounds. 

There  is  great  variety  among  chemical  compounds,  in  the  degree 
in  which  their  properties  are  changed  and  new  properties  produced. 
Thus,  it  is  observed,  that  although  there  is  in  general  no  resemblance 
between  water  and  its  constituent  principles,  oxygen  and  hydrogen,  it 
retains  the  high  refractive  power  which  is  characteristic  of  hydrogen ; 
and  again  the  ammoniacal  salts  formed  between  ammonia  and  the 
acid  gases,  retain  a  great  volatility,  although  in  other  respects  widely 
different  from  their  principles ;  the  muriate  and  the  carbonate  of  am- 
monia are  striking  examples.  There  is  however  no  difficulty  in  as- 
signing such  compounds  to  the  class  that  is  strictly  chemical,  and 
they  would  certainly  not  belong  to  that  which  is  chemico-mechanical. 
This  last  division  is  very  distinctly  separated  from  mere  mechanical 
mixtures ;  silicious  sand  and  lead  shot,  marble  powder  and  powder 
of  clay,  among  solids ;  and  oil  and  water,  and  water  and  mercury, 
among  fluids,  would  never  be  confounded  with  the  class  of  chemi- 
co-mechanical compounds,  which  we  would  separate  from  those  that 
are  truly  chemical.  Nor  is  there  any  difficulty  with  respect  to  cases 
of  mere  superficial  adhesion,  as  between  tallow  and  iron  filings,  at- 
mospheric dust  and  oils,  pollen  and  varnishes  and  paints,  &c.  The 
union  is  mechanical,  and  is  to  be  referred  clearly  to  cohesion  or  ag- 
gregation. 

Admitting  the  distinction  that  has  now  been  attempted  to  be  estab- 
lished, there  can  be  no  hesitation  in  adopting  the  doctrine  of 

DEFINITE    PROPORTIONS. 

(MM.)  IN  ALL  ENERGETIC  COMBINATIONS,  THE  PROPORTIONS  OF 
THE  CONSTITUENT  PRINCIPLES,  WHETHER  THEY  ARE  SIMPLE  OR 
COMPOUND,  ARE  DEFINITE. 


ATTRACTION. 


(ft*.)  Instances  of  definite  compounds  are  innumerable.  —  Thus, 
sulphate  of  baryta,  whether  formed  by  art,  or  existing  for  ages,  as  a 
natural  production,  is  composed  of  baryta  40  parts,  and  sulphuric  acid 
78  ;  and  they  cannot  be  made  to  combine  in  any  other  proportion  ; 
if  the  acid  and  a  solution  of  the  earth  are  mingled  in  any  different 
proportions,  the  ingredient  that  is  in  excess  will  be  left  untouched. 

Baryta  itself  is  composed  of  the  metal  barium  70,  and  oxygen  8= 
78,  and  sulphuric  acid  of  sulphur  16,  and  oxygen  24=40.  Nitrate 
of  potassa  (saltpetre)  is  composed  of  nitric  acid  54,  and  potassa  48= 
102,  and  nitric  acid  is  composed  of  nitrogen  14,  and  oxygen  40  =54, 
and  potassa  of  potassium  40,  and  oxygen  8=48. 

(oo.)  The  combining  power  of  all  bodies  can  be  expressed  by  num- 
bers.*  —  This  remarkable  fact  can  be  rendered  intelligible  by  the  fol- 
lowing instance.  In  the  composition  of  water,  the  oxygen  always 
sustains  to  the  hydrogen  the  proportion  of  8,  by  weight,  the  hydrogen 
being  1,  and  when  they  are  in  the  gaseous  state,  those  proportions 
will  be  found  to  correspond  to  2  volumes  of  hydrogen  and  1  of  oxy- 
gen ;  their  specific  gravities  being  in  the  proportion  of  1  hydrogen  to 
16  oxygen,  it  of  course  requires  a  double  volume  of  hydrogen  to  sus- 
tain the  proportion  by  weight  of  1  to  8. 

(pp>)  In  order  that  numbers  may  express  correctly  the  combining 
power  of  bodies,  they  must  refer  to  a  common  unit.—  -Oxygen  and  hy- 
drogen are  the  bodies  which  have  been  selected  for  this  purpose  :  dif- 
ferent philosophers  have  adopted,  some  the  one  and  some  the  other  5 
but  there  is  in  my  view  a  decided  advantage  in  adopting  hydrogen, 
and  in  expressing  its  lowest  combining  proportion  by  1»  We  thus 
avoid  fractional  expressions,  for  it  would  appear  from  the  researches 
of  Prout  and  others,  that  the  combining  powers  of  all  bodies  may  be 
expressed  by  numbers  which  are  multiples  or  reduplications  of  that 
which  expresses  the  combining  power  of  hydrogen.  We  go  upon 
the  supposition  that  hydrogen  enters  into  combination  with  oxygen  to 
form  water,  in  a  smaller  proportion  than  it  enters  into  the  constitution 
of  any  other  body  ;  and  also  that  there  is  no  body  whatever  that  en- 
ters into  combination  in  so  small  a  proportion  as  hydrogen*  We 
have,  it  is  true,  only  negative  evidence  in  support  of  either  of  these 
propositions,  although  the  presumption  that  they  are  true  amounts  al- 
most to  certainty.  But  should  it  be  hereafter  discovered  that  hydro- 
gen enters  into  some  combination  in  a  less  proportion  than  it  exists  in 
water  ;  or  that  some  other  element  enters  into  combination  in  a  pro- 
portion still  smaller  than  any  known  proportion  of  hydrogen  ;  even 


*  This  most  remarkable  fact  evidently  depends  upon  the  original  constitution  of 
things ;  and  is  as  truly  a  law  of  the  physical  universe,  as  that  its  gravitation  is  direct- 
ly as  the  quantity  of  matter,  and  inversely  as  the  square  of  the  distance. 

21 


162  ATTRACTION, 

then  the  numerical  relations  would  not  be  in  the  least  disturbed,  only 
the  numbers  expressing  them  would  be  doubled,  tripled  or  quadru- 
pled, &ic.  according  as  the  unit  was  placed  lower  in  the  scale.  For 
instance,  should  we  find  a  compound  in  which  hydrogen  exists  in  half 
the  weight  that  it  does  in  water ;  then  the  composition  of  water,  (the 
lowest  known  proportion  of  hydrogen  being  still  unity,)  would  be  ex- 
pressed by  1  of  hydrogen  and  16  of  oxygen,  and  in  the  same  manner 
all  other  numbers  expressing  combining  ratios  would  be  doubled. 

(qq-)  The  foundation  of  the  doctrine  of  definite  proportions  is 
therefore  laid  in  the  constitution  of  things,  and  the  facts  discovered  by 
analysis,  have  been  confirmed  by  calculation. — If  discovery  had  pro- 
ceeded no  farther,  the  knowledge  obtained  would  have  been  both 
highly  valuable  and  interesting,  but  it  was  reserved  for  Mr.  Dalton,* 
to  discover  the  next  law  which,  although  built  upon  that  which  has 
been  already  announced,  is  perhaps  still  more  extraordinary. 

(RR.)  IF  TWO  SUBSTANCES  UNITE,  IN  SEVERAL  DIFFERENT  PRO- 
PORTIONS, THE  LOWEST  COMPOUND  WILL  CONTAIN  ONE,  OR  BOTH 
PRINCIPLES  IN  THEIR  SMALLEST  COMBINING  PROPORTION  ;  AND  IN 
THE  HIGHER,  THE  PROPORTIONS  WILL  BE  SUCH  AS  ARE  PRODUCED 
BY  MULTIPLYING  THE  LOWEST  BY  SOME  WHOLE  NUMBER. 

In  a  word,  the  higher  proportions  are  multiples  of  the  lowest,  by 
a  whole  number,  or,  the  difference  will  be  expressed  by  a  whole 
number,  and  the  lowest  is  generally  a  divisor  of  the  higher  without 
a  remainder. 

In  compounds  of  A-fB,  supposing  the  first  compound  to  be  of  the 
smallest  proportions  of  each,  and  that  A  remains  constant,  then  the 
other  compounds  will  be  A+2B,  or  -f  3B,  or  -f  4B. 

"  The  following  tablef  will  illustrate  the  subject. 

Water  is  composed  of  hydrogen  1.  oxygen 

Deutoxide  of  hydrogen         do.  1,  do.  16 

Carbonic  oxide,  carbon  6,  do.  8 

Carbonic  acid,                       do.  6,  do.  16 

Nitrous  oxide,  nitrogen  14,  do.  8 

Nitric  oxide,                          do.  14,  do.  16 

Hyponitrous  acid,                 do.  14,  do. 

Nitrous  acid,                          do.  14,  do.  32 

Nitric  acid,                           do.  14,  do.  40" 

In  the  two  first  lines,  the  proportion  of  hydrogen  is  the  same,  while 
in  the  second  that  of  the  oxygen  is  doubled ;  in  the  third  and  fourth 
lines,  similar  relations  exist  between  carbon  and  oxygen,  and  in  the 


*  Of  Manchester,  England,  who  is  still  living.  i  Turner,  2d  ed.  p.  151. 


ATTRACTION. 

four  last,  while  the  proportion  of  nitrogen  is  constant,  that  of  the 
oxygen  is  double,  triple,  quadruple,  and  quintuple. 

This  is  the  law  that  has  usually  been  called  the  law  of  multiples, 
or  of  multiple  proportions,  and  there  can  be  no  doubt  that  it  is  true 
to  a  very  great  extent,  although,  at  present,  we  are  prevented,  by  a 
very  few  apparent  exceptions,  from  regarding  it  as  quite  universal. 

Thus,  hydrogen  being  1,  lead  is  represented  by  the  number  104, 
and  manganese  by  28,  and  each  of  these  metals  has  three  oxides, 
which  are  found  to  contain  respectively,  8,  12,  and  16  of  oxygen, 
which  is  in  the  proportion  of  1  1.5  and  2  ;  so  iron,  whose  equivalent 
is  28  has,  in  its  two  oxides,  8  and  12  of  oxygen,  which  also  are  in  the 
proportion  of  1,  and  1.5.  This  does  not  correspond  with  the  doc- 
trine of  multiple  proportions ;  the  difficulty  would,  however,  be  re- 
moved, should  an  oxide  of  each  of  these  metals  be  discovered,  with 
4  of  oxygen,  instead  of  8 ;  or  possibly  there  may  have  been  a  mix- 
ture of  oxides,  as  of  the  protoxide  and  peroxide  of  lead,  thus  giving 
origin  to  an  apparent  deutoxide,  which  may  not  really  exist.*  Should 
these  cases,  however,  prove  in  the  end  to  be  exceptions,  they  will 
not  invalidate  the  truth  of  the  general  doctrine. 

(ss.)  The  number  representing  any  compound  body  is  composed  of 
the  sum  of  the  numbers  representing  its  parts. — Thus  in  sulphate 
of  potash,  whose  equivalent  is  88,  sulphur  16,  -f- 3  proportions  of 
oxygen  24=40,  and  potassa  is  composed  of  potassium  40,  and  1  pro- 
portion of  oxygen,  8=48,  which  +  40=88;  this  will  hold  true  of 
the  most  complicated  as  well  as  of  the  most  simple  compounds. 

This  truth  is  well  illustrated  by  all  the  salts. 

(tt.)  "  The  respective  quantities  of  any  number  of  alkaline,  earthy, 
and  metallic  bases  required  to  saturate  a  given  quantity  of  any  acid, 
are  always  in  the  same  ratio  to  each  other,  to  what  acid  soever  they 
may  be  applied  "\ — Soda  2  parts,  and  potassa  three  parts  respective- 
ly, these  numbers  always  bearing  the  same  relation  to  each  other, 
and  to  some  unit,  saturate  every  acid  ;  soda  is  represented  by  32, 
and  potassa  by  48,  hydrogen  being  one,  and  32 : 48  : :  2  :  3,  as  above, 
and  these  numbers  therefore  constantly  represent  the  combining 
power  of  these  two  alkalies ;  but  the  proportions  of  the  different  acids 
which  will  combine  with  these,  and  with  other  bases,  will  of  course 
vary. 

(uu.)  "  The  respective  quantities  of  any  number  of  acids  requir- 
ed to  saturate  a  given  quantity  of  any  base,  are  always  in  the. 
same  ratio  to  each  other,  to  what  base  soever  they  may  be  applied."^ 
— This  is  only  the  converse  of  the  other  proposition,  the  relative  pro- 
portions of  any  two  acids  that  saturate  a  given  base,  will  saturate  any 


*  Turner.  t  Prof.  Olmsted,  in  Am,  Jour,  Vol.  XII,  p.  1. 


J64  ATTRACTION. 

other  base,  and  are  therefore  called  chemical  equivalents,  and  the 
same  is  true  of  the  bases,  in  relation  to  the  acids. 

Wenzel,  a  German  chemist,  proved,  in  a  work  published  in  1777, 
that  two  neutral  salts  that  decompose  each  other,  still  preserve  their 
neutrality ;  neither  acid  nor  base  being  in  excess,*  and  Richter,  of 
Berlin,  illustrated  this  truth  more  fully  in  1792.  This  could  not 
have  been  true,  had  not  the  relations  of  acids  and  bases  been  con- 
stant, as  stated  in  the  two  last  propositions.  Thus,  in  sulphate  of 
potassa,  the  acid  is  in  the  proportion  40,  and  the  alkali  48=88,  and 
in  nitrate  of  baryta  the  acid  is  54,  and  the  earth  78  =  132.  Now 
when  these  salts  are,  by  double  decomposition,  converted  into  sul- 
phate of  baryta,  and  nitrate  of  potassa,  the  54  parts  of  nitric  acid  in 
the  nitrate  of  baryta  will  saturate  and  be  saturated  by  the  48  parts  of 
potassa  in  the  sulphate  of  potassa,  making  102  of  the  new  salt,  the 
nitrate  of  potassa,  and  the  40  of  sulphuric  acid  in  the  sulphate  of 
potassa,  will  saturate  and  be  saturated  by  the  78  of  baryta,  in  the 
nitrate  of  baryta,  making  118  of  the  sulphate  of  baryta.  The  facts 
may  be  concisely  expressed  thus. 

Before  decomposition. 

Sulphuric  acid  40 -f  potassa  48=   88  sulphate  of  potassa. 
Nitric  acid         54  -j-   baryta    78  =  132  nitrate  of  buryta. 

"220 
Jlfter  decomposition. 

Sulphuric  acid  40 -f  baryta  78  =  118  sulphate  of  baryta. 
Nitric  acid         54-}-  potassa  48  =  102  nitrate  of  potassa. 

220~ 

The  sum  of  the  constituents  being  the  same  after  decomposition 
as  before,  it  is  obvious  there  can  be  no  excess  of  either. 

Thus  then,  hydrogen  being  unity,  we  are  to  infer  that  40,  or  a 
multiple  of  it  by  a  whole  number,  will  always  express  the  combining 
power  of  sulphuric  acid,  and  so  of  other  principles. 

(W.)  CHEMICAL  EQUIVALENTS  ARE  THOSE  DEFINITE  QUANTI- 
TIES OF  PARTICULAR  SUBSTANCES  THAT  SATURATE  DEFINITE  QUAN- 
TITIES OF  OTHER  SUBSTANCES. 

This  is  only  expressing  in  the  form  of  a  proposition,  what  has  been 
already  stated  ;  namely,  that  a  unit  being  chosen,  it  becomes  possible 
to  express  the  combining  power  of  all  bodies,  both  simple  and  com- 
pound, by  numbers.  Thus,  if  the  combining  power  of  hydrogen  be 


*  For  an  interesting  account  of  the  progress  of  the  doctrine  of  definite  proportions 
see  the  introduction  to  Dr.  Thomson's  First  Principles  of  Chemistry. 


ATTRACTION  165 

expressed  by  1,  that  of  oxygen  will  be  8,  that  of  carbon  6,  that  of 
sulphur  16.  If  hydrogen  and  oxygen  unite  in  one  proportion  of  each, 
the  compound  will  be  expressed  by  9, — this  is  the  number  repre- 
senting water,  and  every  combination  of  water  will  be  expressed  by 
9,  or  18,  or  27,  or  36,  and  so  on,  even  to  ten  proportions,  which 
would  be  expressed  by  90. 

(ww.)  The  combining  weight  or  power  of  a  body  being  once  ascer- 
tained, it  will  always  remain  the  same ;  or  it  will  sustain  the  same  ra- 
tio in  every  combination. — If  the  combination  takes  place  in  different 
proportions  with  a  given  body,  the  number  expressing  the  lowest  pro- 
portion will  be  constant,  and  the  higher  proportions  will  be  multiples 
of  it,  by  a  whole  number.  Thus,  hydrogen  being  unity,  oxygen  will 
always  enter  into  combination  in  the  proportion  8,  16,  24,  32,  &c. ; 
carbon  in  the  proportions  6,  12,  18,  24,  &ic.  The  combining  weights 
or  powers  of  bodies,  both  simple  and  compound,  may  therefore  be  per- 
manently registered  in  a  table  of  chemical  equivalents.  Such  a  ta- 
ble is  now  attached  to  every  treatise  on  chemistry,  and  is  constantly 
referred  to  in  practical  operations,  both  of  science  and  art.  It  is  an 
important  auxiliary,  for  we  discover  by  inspection  what  quantities 
of  particular  bodies  saturate,  or  are  equivalent  to  each  other.  In 
the  present  work  the  chemical  equivalents,  as  far  as  they  are  ascer- 
tained, will  be  found  connected  with  each  body,  in  its  proper  place, 
and  they  will  be  collected  in  a  table  at  the  end.* 

Dr.  'Wollaston1  s  Scale  of  chemical  equivalents.^ — This  is  a  table  of 
combining  or  proportional  weights,  embracing  those  bodies  that  are 
most  frequently  used  in  practical  chemistry.  It  differs  from  other 
tables  only  in  this,  that  while  the  names  of  the  substances  are  station- 
ary, those  of  the  numbers  are  placed  on  a  sliding  rule,  divided  logo- 
metrically,  according  to  the  principle  of  that  of  Gunter.  The  advan- 
tage of  the  instrument  is,  then,  that  it  not  only  presents  a  table  of 
chemical  equivalents,  but  by  moving  the  sliding  rule  in  a  proper  man- 
ner, many  proportions  can  be  mechanically  worked,  without  the 
trouble  of  calculation.  Thus,  it  has  been  already  stated,  that  sul- 
phate of  potassa  is  composed  of  acid  40+  potassa  48,  and  therefore 
88  is  the  number  expressing  the  composition  of  the  salt ;  hydrogen 
being  the  unit,  all  this  will  be  seen,  by  placing  the  scale  in  such  a  po- 
sition that  8  is  opposite  to  oxygen ;  but  if  we  wish  to  know  what 
would  be  the  proportion  of  the  acid  and  alkali,  in  100  parts  of  sul- 
phate of  potassa,  we  have  only  to  bring  the  scale  into  such  a  posi- 
tion, that  100  will  be  opposite  to  sulphate  of  potassa,  when  we  shall 


*  A  very  valuable  table  is  annexed  to  Dr.  Thomson's  First  Principles  of  Chem- 
istry, and  Mr.  Brande  has  published,  in  a  separate  work,  the  equivalents  of  all  bodies 
as  far  as  they  are  known. 

t  For  a  description  of  this  beautiful  instrument,  see  the  Phil.  Tr.  for  1814. 


lt>6  ATTRACTION. 

read  opposite  to  potassa  54.5,  and  to  sulphuric  acid  45.5,  which  is 
the  composition  in  100  parts. 

Dr.  Wollaston  called  oxygen  10.  When  this  number  was  oppo- 
site to  oxygen,  the  other  numbers,  therefore,  estimated  by  that  scale, 
represented  "  the  combining  weights  of  the  bodies  opposite  to  which 
they  may  be  found."  "  By  mere  inspection  of  this  scale,  we  dis- 
cover the  quantity  of  one  body  which  enters  into  combination  with 
another,  the  proportions  of  the  elements  of  compounds,  and  the 
quantities  of  these  which  enter  into  the  composition  of  any  particu- 
lar weight  of  a  compound ;  the  quantity  of  any  substance  required 
to  decompose  a  compound,  by  combining  with  either  of  its  ingredi- 
ents, and  the  quantity  of  the  products  that  will  be  formed."  The 
progress  of  analysis  has  shewn  that  the  numbers  attached  to  Dr.  Wol- 
laston's  scale  are,  in  many  instances,  incorrect,  but  these  errors  have 
been  rectified  in  more  recent  editions  of  the  scale,*  in  which,  also, 
the  more  convenient  unit  of  hydrogen  has  been  adopted. 

It  is  now  ascertained  that  the  foundations  of  chemical  combination 
are  laid  in  mathematical  relations,  and  the  proportions  of  bodies  have 
therefore  become  subjects  of  mathematical  calculation,  as  well  as  of 
analytical  experiment.  The  mathematical  relations  are  proved  by 
analysis,  to  be  true,  and  analysis  is,  in  its  turn,  guided  and  corrected 
by  calculation.  We  may  be  assured  that  an  analysis  is  wrong  if  it 
does  not  correspond  with  numerical  ratios,  and  we  may  predict  that 
the  result  will  be  expressed  by  one  of  a  certain  set  of  numbers,  rela- 
ted to  each  other  by  the  same  ratio,  provided  we  are  correctly  ac- 
quainted with  any  one  combination  of  the  same  principles ;  the  new 
compound  of  these  principles  will  bear  a  relation  to  them  which  may 
be  expressed  by  whole  numbers,  although  we  cannot  be  certain 
whether  it  will  be  double,  triple,  quadruple ;  or  a  half,  or  a  third, 
or  a  fourth,  &c.  of  the  one  known  ;  it  will  be  certain,  or  in  the 
highest  degree  probable,  that  it  will  not  be  expressed  by  any  inter- 
mediate number. 

This  beautiful  discovery,  as  its  foundations  are  laid  in  the  exact 
relations  of  quantity,  places  chemistry  upon  a  mathematical  basis. 

Mr.  Higgins  gave  the  first  hint  of  this  subject  in  1788,  in  his  view 
of  the  phlogistic  and  anti-phlogistic  theory,  but  Mr.  Dalton  first  clear- 
ly explained  the  doctrine. 

COMBINATION    BY    VOLUMES. 

(XX.)  GASEOUS  BODIES  UNITE  BY  VOLUME,  IN  THE  SIMPLE 
RATIO  OF  1  TO  1,  1  TO  2,  1  TO  3,  1  TO  4,  &c. — This  law  was  es- 


*  As  by  Mr.  Reid,  in  Britain,  and  by  Messrs.  Henry  and  Beck,  of  the  Rensselaer 
School  at  Troy,  N.  Y.,  and  by  Dr.  Barrat,  at  Middletown,  Con. 


ATTRACTION.  1(57 

tablished  by  Gay  Lussac,  and  Humboldt,*  and  the  first  fact  of  the 
kind  observed,  was  in  the  case  of  the  elements  of  water,  two  vol- 
umes of  hydrogen  combining  with  one  volume  of  oxygen. 

The  following  tablesf  exhibit  a  number  of  facts  of  this  class. 

Volumes.  Volumes. 

100  muriatic  acid  gas  combine  with   100  ammoniacal  gas. 

100  carbonic  acid  gas,  "  "      100         do.          do. 

100       do.       do.  «  "      200         do.          do. 

100  nitrogen  gas,  "  "        50  oxygen  gas, 

100       do.  "  "      100         do. 

100       do.  "  "      150         do. 

100       do.  "  "      200         do. 

100       do.  «  «      250         do. 

100  Chlorine  gas,  "  "      100  hydrogen  gas. 

100  nitrogen  gas,  "  "      300         do. 

100  oxygen  gas,  "  "      200         do. 

This  table  needs  no  comment ;  supposing  it  to  be  accurate,  of 
which  there  can  be  no  reasonable  doubt,  it  fully  supports  the  propo- 
sition stated  above. 

(yy.)  Bodies  in  the  state  of  vapor  obey  the  same  law. 
11 100  vols.  hydrogen  +  100  vols.  vapor  of  sulphur  =  sulph'd  hydrogen, 
100       "       oxygen  -j- 100         "  "          =  sulphurous  acid. 

100       "  "     -f-100         «         iodine       =  hydriodic  acid."J 

This  view  is  carried  so  far  as  even  to  embrace  solids,  which,  per- 
haps, have  never  been  in  the  aeriform  condition,  except  in  a  state  of 
combination ;  it  is  supposed  that  in  that  state,  they  would  obey  the  same 
rule.  In  the  compound  gases  just  mentioned,  it  is  obvious  that  the 
specific  gravity  and  proportion  of  the  oxygen  in  sulphurous  acid,  and 
of  the  hydrogen  in  sulphuretted  hydrogen  being  known,  the  balance 
of  the  weight  of  the  gas  under  a  given  volume,  must  represent  the 
sulphur  in  the  state  of  vapor ;  and  the  same  remark  will  apply  to  the 
hydriodic  acid  ;  we  may  include  the  carburetted  hydrogen  gases  in 
the  same  view,  for  the  specific  gravity  of  the  hydrogen  which  they 
contain,  and  its  proportion  being  known,  it  is  obvious  that  the  remain- 
der of  the  weight  in  a  given  volume  must  be  carbon  in  a  state  of 
vapor. 

(zz.)  When  gases  suffer  condensation,  in  consequence  of  com- 
bining, it  is  always  in  a  simple  ratio  to  the  volume  of  one  of  them. — 
Ammonia  is  composed  of  3  vols.  of  hydrogen  -f  1  vol.  of  nitrogen, 
contracted  into  2  vols.  and  in  the  formation  of  nitrous  oxide  gas  there 


Memoires  d'Arcueil.  t  Murray,  6th  Ed.  Vol.  1,  p.  67. 


168  ATTRACTION. 

is  a  contraction  to  two  thirds.  In  the  formation  of  sulphuretted  hy- 
drogen, and  sulphurous  acid,  there  is  also  a  contraction  to  one  half ; 
and  the  same  fact  is  seen  in  many  other  cases. 

(aaa.)  By  knowing  the  specific  gravity  of  the  gases  composing  a 
compound  gas,  and  the  degree  of  condensation  which  they  undergo, 
the  specific  gravity  of  the  compound  gas  may  be  calculated. — Dr. 
Turner  has  given  the  following  instances  among  others.  Ammonia,  as 
just  observed,  contains  3  vols.  hydrogen,  and  1  of  nitrogen,  condensed 
into  2  vols.  The  sp.  gr.  of  hydrogen  is  0.0694,  air  being  1,  and  that 
of  nitrogen  is  0.9 722 —  therefore  the  latter  number +0.0694X3  = 

— =0.2951,  the  sp.  gr.  which  ammoniacal  gas  would  have, 

4 

were  there  no  contraction  of  the  gases ;  but  as  they  contract  one  half, 
the  sp.  gr.  will  be  double  of  that,  or  0.5902,  which  is  its  weight,  as 
ascertained  by  experiment  by  Sir  H.  Davy.  Nitric  oxide  gas,  be- 
ing composed  of  100  vols.  of  oxygen,  and  100  of  nitrogen,  united 
without  contraction,  must  form  200  volumes  of  the  compound, 
and  of  course  the  sp.  gr.  must  be  the  mean  of  its  components,  or 

— 3LJ — _  =  1.0416,  which  accords  with  the  average  results 

of  the  best  experiments. 

(bbb.)  The  combinations  by  volume  coincide  accurately  with  the 
law  of  multiple  proportions,  for  it  is  obvious  that  double,  triple,  fyc. 
of  the  volume  of  a  gas  must  also  be  double,  triple,  fyc.  of  the  weight. 
— There  is  also  an  additional  coincidence,  that  is  not  possessed  by 
the  compounds  that  are  not  aeriform.  Although  in  them  there  is  an 
arithmetical  relation  between  the  weights  of  the  different  proportions  of 
the  same  principle,  there  is  no  such  correspondence  between  the  dif- 
ferent principles  of  the  same  compound.  Thus,  between  the  14  parts 
by  weight,  of  nitrogen,  and  the  8  of  oxygen,  contained  in  nitrous 
oxide ;  and  the  14  and  16  parts  of  the  same  principles,  in  nitric  ox- 
ide ;  and  the  6  of  carbon,  and  8  of  oxygen,  in  carbonic  oxide  ;  and 
the  6  and  16  of  the  same  principles  in  carbonic  acid,  there  is  no  mul- 
tiple relation. 

(ccc.)  In  combinations  of  aeriform  bodies,  there  is  a  multiple  re- 
lation, not  only  between  the  different  proportions  of  the  same  princi- 
ple, but  of  the  different  principles,  that  are  united  in  the  same  com- 
pound.— The  table  on  page  167  proves  this  proposition  to  be  true. 

(ddd.)  In  general,  a  volume  of  a  gas  represents  a  combining  pro- 
portion.— Oxygen  is  the  only  exception  ;  in  that  gas,  half  a  volume 
represents  a  combining  proportion.  This  arises  from  the  fact  that  in 
the  lowest  combination  of  oxygen  known,  it  unites  with  two  volumes 
of  hydrogen,  which  are  supposed  to  contain  only  one  combining  pro- 
portion, and  therefore  the  combining  proportion  of  oxygen  is  consid- 
ered as  contained  in  half  a  volume  of  that  gas. 


ATTRACTION.  169 

(eee.)  .Although,  in  general,  there  is  no  arithmetical  ratio  between 
the  combining  proportions  of  different  bodies,  hydrogen  forms  an  ex- 
ception.— According  to  Dr.  Prout,*  and  Dr.  Thomson, f  "in -every 
one  of  the  compounds  of  hydrogen,  the  proportion  of  the  body  united 
with  it,  is  an  exact  multiple,  by  a  whole  number,  of  its  own  weight."  J 
Thus,  in  water,  (protoxide  of  hydrogen,)  the  oxygen  is  just  8  times 
the  weight  of  the  hydrogen,  while  in  the  deutoxide,  it  is  16  times  ;  and 
in  sulphuretted  hydrogen,  the  sulphur  is  just  16  times  the  weight 
of  the1  hydrogen. 

(fff')  Berzelius^  has  discovered  that  oxygen  contained  in  different 
proximate  principles  of  the  same  compound,  exists  in  a  multiple  ratio, 
or  in  equality. — Thus,  hydrate  of  potassa  is  composed  of  potassa  48, 
and  of  water  9,  and  there  is  8  of  oxygen  in  each  of  them.  This  law 
holds  in  earthy  minerals,  containing  several  oxides,  and  in  the  salts. 

Carbonate  of  potassa  consists  of  carbonic  acid  22,  containing  oxy- 
gen 16,  and  of  potassa  48,  containing  oxygen  8. 

Where  water  of  crystallization  is  present,  there  is  a  similar  rela- 
tion.— Crystallized  sulphate  of  soda  contains  sulphuric  acid  40,  in 
which  the  oxygen  is  24;  soda  32,  with  oxygen  8,  and  water  90, 
with  oxygen  80;  and  these  numbers,  8,  24,  and  80,  consist  of  one, 
three,  and  ten  proportions  of  oxygen. 

Compound  salts  obey  the  same  law. — In  tartrate  of  potassa  and 
soda,  the  oxygen  in  the  acid,  and  in  the  two  alkalies  is  the  same. 

(ggg.)  "  In  each  series  of  salts  the  same  relation  always  exists 
between  the  oxygen  of  the  acid  and  of  the  base."  In  the  neutral  sul- 
phates, the  ratio  is  as  1  to  3 — one  in  the  alkali,  and  three  in  the  acid. 
In  the  carbonates  the  acid  is  double,  and  in  the  bi-carbonates,  quad- 
ruple the  oxygen  of  the  base. 

The  illustrious  discoverer  of  these  most  remarkable  laws,  says  that 
in  the  course  of  several  years  that  have  passed  since  he  first  observ- 
ed them,  he  has  not  detected  any  exception,  and  he  therefore  relies 
upon  them  implicitly,  and  is  in  the  habit  of  calculating  the  compo- 
sition of  bodies  upon  this  principle.  || 


*  Annals  of  Philosophy,  Old  Series,  Vol.  VI,  p.  321. 

t  First  Principles. 

t  This  is  denied  by  Berzelius,  who  asserts  that  it  is  inconsistent  with  the  results  of 
his  analysis. 

§  This  account  of  the  discoveries  of  Berzelius,  is  abridged  from  Dr.  Turner  s 
Chemistry,  2d  Ed. 

||  For  an  able  view  of  this  subject,  see  Dr.  Turner's  Chemistry,  2d  Ed.  p.  177. — 
He  gives  the  following  generalization.  Most  of  the  neutral  sulphates,  all  the  alka- 
line and  earthy,  and  several  metallic  sulphates  of  common  metals,  as  iron,  zinc,  and 
lead,  consist  of  1  proportion  of  acid,  and  1  of  base  ;  the  acid  contains  1  proportion  of 
sulphur,  16,  and  3  of  oxygen,  24,  and  every  protoxide  consists  of  metal  1  propor- 
tion, and  oxygen  1=8.  It  will  be  seen  by  comparing  the  numbers  that 

1.  "  The  oxygen  of  the  acid  is  a  multiple  of  that  of  the  base." 

2    ««  The  acid  contains  three  times  as  much  oxygen  as  the  base," 

22 


170  ATTRACTION. 


THEORY    OF    ATOMS. 

For  a  complete  view  of  this  curious  and  interesting  speculation,  re- 
course must  be  had  to  the  writings  of  Higgins^  Dalton,  Berzelius, 
Thomson  and  others.* 

In  the  sketch  that  has  been  given  of  definite  proportions,  I  have  in- 
tentionally avoided  the  use  of  the  word  atom,  because  it  may  be  mis- 
understood, and  may  lead  beginners  to  confound  facts  with  hypothe- 
sis. The  doctrine  of  definite  and  multiple  proportions  is  established 
on  the  basis  of  experiment,  and  is  fully  confirmed  both  by  analysis 
and  calculation. 

The  expressions,  combining  weight,  combining  quantity,  or  combin- 
ing proportion,  and  chemical  equivalent,  all  mean  the  same  thing  ;  and 
it  may  be  added,  that  atom,  and  atomic  constitution  and  atomic  weight, 
are  used  by  most  writers  in  the  same  sense.  The  atomic  hypothesis, 
first  suggested  by  Mr.  Higgins,  (1789,)  was  so  fully  detailed  and  illus- 
trated by  Mr.  Dalton,  in  his  Chemical  Philosophy,  that  the  theory  is 
usually  considered  as  his.  It  is  ingenious  and  beautiful,  and  there 
can  be  no  reasonable  doubt  that  matter  has  an  atomic  constitution  ; 
but,  that  it  is  such  as  the  atomic  theory  now  in  discussion  supposes, 
although  highly  probable,  cannot  be  demonstrated  ;  and  it  is  there- 
fore important  for  the  student  to  be  able  to  distinguish  it,  or  any  other 
atomic  theory  that  may  be  proposed,  from  the  luminous  and  demon- 
strated verity  of  definite  and  multiple  proportions. 

(AM.)  If  we  assume  that  bodies,  in  the  combination  in  which  they 
exist  in  the  smallest  proportions,  unite  atom  and  atom,  then  their  re- 
lative weights  in  those  cases,  will  represent  those  of  their  atoms. 
This  assumption  is  the  foundation  of  the  atomic  theory. 

(Hi.)  There  being  no  combination  in  which  hydrogen  is  known  to 
exist  in  smaller  proportion  than  in  water,  and  the  specific  gravity  of 
hydrogen  to  oxygen  being  as  1:16,  if  these  elements  unite  atom  to 
atom,  and  a  volume  of  each  represents  an  atom,  then  the  relative 


3.  "  The  sulphur  of  the  acid  is  just  double  the  oxygen  of  the  base." 

4.  The  acid  itself  is  just  five  times  as  much  as  the  oxygen  of  the  base. 

Metallic  sulphurets  often  contain  one  proportion  of  each  element,  and  when  con- 
verted into  a  salt,  the  sulphuric  acid  and  the  protoxide  will  be  exactly  in  the  propor- 
tion for  forming  a  neutral  sulphate  of  a  protoxide. 

In  the  carbonates,  the  oxygen  of  the  acid  is  generally  double  that  of  the  base,  and 
a  similar  mode  of  reasoning  is  applicable  to  the  various  genera  of  salts ;  but  no  con- 
stant ratio  exists  between  the  quantity  of  oxide  and  that  of  the  acid,  or  of  the  oxygen 
in  the  acid,  because  the  combining  weights  of  the  metals  themselves  are  different. 
All  these  facts  are  arranged  naturally  under  Mr.  Dalton's  principle  of  multiple  pro- 
portions. 

An  attempt  has  been  made  to  extend  the  same  views  to  the  constitution  of  miner- 
als.—See  Ann.  of  Philosophy,  N.  S.  Vol.  IX,  Mr.  Children. 

*  See  Henry,  10th  London  Ed.  Vol.  I,  p.  42.  Thomson's  First  Principles  of 
Chemistry,  and  Turner  and  Murray. 


ATTRACTION.  171 

weights  of  the  atoms  will  be  as  those  numbers  ;  but  as  it  requires  two 
volumes  of  hydrogen  gas  to  saturate  one  volume  of  oxygen  gas,  it 
follows  that  if  the  two  volumes  of  hydrogen  be  expressed  by  1,  viz. 
be  regarded  as  one  atom,  half  a  volume  of  oxygen  must  be  the 
equivalent  of  the  hydrogen,  arid  will  be  expressed  by  8.* 

(jjj>)  Either  of  these  elementsf  being  taken  as  unity,  then  the 
weights  of  the  atoms  of  other  bodies  may  also  be  expressed  by 
numbers,  having  an  arithmetical  relation  to  those  attached  to  these 
two  elements,  and  thus  we  may  construct  a  table  of  atomic  weights. 

(kkk.)  If  we  could  be  certain  that  we  actually  know  the  lowest  pro- 
portions in  which  bodies  combine,  and  that  in  them  the  constituents 
are  united  atom  and  atom,  then  their  definite  proportions  and  their 
atomic  weights  would  correspond  ;  or  at  least  they  would  be  multiples 
and  divisors,  generally,  of  each  other,  and  always  by  whole  numbers. 

(III.)  But  we  can  never  be  certain,  that  we  either  know  the  small- 
est combining  quantities  of  bodies,  or  that  those  quantities,  if  known, 
are  relatively  in  the  proportion  of  atom  and  atom,  or  of  one  atom  of 
one  and  of  two  of  another,  or  vice  versa,  or  of  some  other  pro- 
portion ;  we  cannot  therefore  be  certain  that  our  atomic  hypothesis  is 
true. 

(mmm.)  This  however  does  not  affect  the  truth  of  the  theory  of 
multiple  proportions ;  that  great  discovery  is  independent  of  hypothe- 
sis, because  the  exactness  and  arithmetical  relation  of  the  proportions 
is  a  matter  of  fact,  and  will  still  be  true,  whether  the  lowest  combin- 
ation is  formed  by  atom  and  atom  of  different  bodies,  or  by  one  atom 
of  one  and  two  of  another,  or  the  reverse  ;  or  by  any  other  assort- 
ment that  may  be  imagined. 

(nnn.)  The  atomic  theory  is  an  elegant  hypothesis,  framed  to  ac- 
count for  definite  and  multiple  proportions,  and  may  be  either  true 
or  false  without  affecting  that  sublime  truth,  which  deserves  to  be  in- 
scribed on  the  same  tablet  with  the  laws  of  gravitation  and  projection. 

(ooo.)  Still  the  hypothesis  is  highly  probable,  and  the  probability 
of  its  truth  is  much  increased  by  its  surprising  coincidence  with 
facts. 

(ppp-)  No  student  in  chemistry,  should  however,  imagine  that  the 
doctrine  of  definite  and  multiple  proportions  must  stand  or  fall  with 
the  atomic  theory.  The  latter  may  be  discarded,  without  in  the  least 
affecting  the  former ;  but  the  truth  of  the  former  is  indispensable  to 
the  existence  of  the  latter. 

I  shall,  as  much  as  possible,  avoid  the  use  of  the  word  atom,  since  we 
have  no  positive  knowledge  of  the  nature,  forms,  number  and  weight 
of  the  atoms  of  any  thing ;  as  the  word  is  short,  it  may  however 

*  See  Mr.  Finch's  paper  on  the  atomic  theory,  Am.  Jour.  Vol.  XIV,  p.  24. 
t  Other  elements  might  have  been  used  for  this  purpose  ;  but  none  are  equally 
oxygen  and  hydrogen. 


172  ATTRACTION. 

be  convenient  to  use  it  occasionally,  but  it  will  be  understood  by  the 
reader,  that  nothing  more  is  intended  by  it  than  combining  weight, 
combining  proportion,  or  chemical  equivalent.* 

It  will  doubtless  be  thought  by  some,  that  the  atomic  theory  should 
be  presented  more  in  detail.  There  can  be  no  objection  to  its  be- 
ing studied  fully  by  those  who  are  well  versed  in  chemistry,  but  the 
learners  of  elements,  for  whom  chiefly  this  work  is  intended,  will,  if 
they  have  mastered  the  doctrine  of  definite  and  multiple  proportions, 
be  able  to  go  forward  in  their  studies  without  the  atomic  theory,  and 
to  understand  that  theory  the  better,  the  farther  they  proceed  in  the 
science.  We  do  not,  however,  hold  it  in  small  consideration,  and  a 
sufficient  number  of  opportunities  of  illustrating  its  nature,  will  pre- 
sent themselves  in  the  study  of  the  particular  bodies. f 

APPENDIX  TO  ATTRACTION. 

Terrestrial  and  artificial  magnetism,  has  an  evident  effect  on  chem- 
ical action. — Before  leaving  the  subject  of  attraction,  it  ought  to  be 
remembered,  that  magnetism  appears  to  be  connected  with  it.  Tinc- 
ture of  purple  cabbage  placed  in  a  syphon  tube,  is  changed  in  fifteen 
minutes  to  green,  by  being  connected  by  an  iron  wire,  with  the  two 
poles  of  a  magnet,  and  when  the  liquor  was  in  two  connected  tubes, 
the  same  thing  happened,  but  it  required  two  days  to  effect  the 
change.  J 

A'  syphon  tube,  half  an  inch  wide,  and  four  and  five  inches  long, 
having  mercury  poured  into  the  bend,  but  not  sufficient  to  cut  off  the 
communication  between  the  two  branches  ;  the  tube  is  then  nearly 
filled  wijth  an  acid  solution  of  nitrate  of  silver.  The  tube  being  placed 
in  the  plane  of  tlie  magnetic  meridian,  the  precipitation  of  the  arbor 
dianse§  is  much  more  rapid  than  when  it  is  at  right  angles  with  it;  and  it 
is  much  more  abundant  at  the  north  than  at  the  south  end,  and  the 
crystals  are  more  brilliant  and  longer,  and  more  perfect. 

A  bent  tube  placed  across  the  magnetic  meridian,  and  in  which 
the  crystallization  has  made  little  progress,  exhibits  it  in  increased 
activity,  when  two  artificial  magnets  are  approached,  the  north  pole 

*Dh  "VVollaston,  in  a  paper  on  the  finite  extent  of  the  atmosphere,  published  in 
the  Phil.  Transactions  for  1822,  has  rendered  it  probable  that  there  are  atmospheri- 
cal atoms  incapable  of  farther  division.  The  question  as  to  the  indivisibility  of 
atoms,  is  a  physical  topic,  entirely  independent  of  the  mathematical  speculation  as  to 
the  infinite  divisibility  of  matter ;  a  speculation  which  seems  however  to  have  little 
utility,  and  some  would  say,  meaning,  except  with  reference  to  physical  elements. 

t  Thenard  has  followed  this  course,  Vol.  I,  Chem.  p.  24,  Ed.  5.  I  heard  Mr. 
Dalton  explain  his  own  theory  in  his  lecture  room  at  Manchester,  and  while  I 
was  entertained  with  the  arrangement  of  his  atomic  symbols,  I  was  forcibly  struck 
with  the  stiil  greater  value  of  his  discovery  of  multiple  proportions. 

i  The  spontaneous  change  is  to  red  and  not  to  green. 

§  A  fanciful  name  given  to  this  peculiar  crystallization  of  silver;  the  disposition 
of  the  crystals  being  in  branches,  and  silver  was  formerly  called  Luna  or  Diana. 


ATTRACTION.  173 

of  one  to  one  leg,  and  the  south  pole  of  the  other  to  the  other  leg  of 
the  syphon  tube.  Circles  of  tallow  being  formed  on  glass  plates,  so- 
lution of  nitrate  of  silver  was  placed  within,  and  a  circular  piece  of 
zinc  in  the  centre  ;  the  precipitation  of  silver  was  much  more  active 
towards  the  north,  and  the  oxide  of  zinc  inclined  to  the  south  ;  a 
strong  magnet  being  brought  within  two  inches  of  a  plate  prepared,  as 
before,  the  precipitation  took  place  in  one  fourth  of  the  time,  that  it 
did  on  the  plates  that  were  beyond  its  influence.* 

•»  *  *  *  •*  -x- 

We  have  now  taken  a  preliminary  view,  perhaps  sufficiently  ex- 
tensive and  detailed,  of  the  general  doctrines  of  chemistry.  This  was 
indispensable,  to  enable  us  to  understand  the  history  of  particular  bo- 
dies, which  is  to  follow ;  and  in  giving  it,  I  have  endeavored,  as  far 
as  practicable,  to  avoid  anticipation ;  still  it  is  possible  that  some  pas- 
sages may  be  unintelligible  to  a  beginner ;  as  they  are,  however,  not 
numerous,  they  may  be  omitted  in  the  first  reading,  and  being  mark- 
ed in  the  margin  by  a  pencil,  they  can  be  examined  again  at  a  more 
advanced  stage  of  the  subject,  when  the  pupil  has  become  more 
familiar  with  chemical  facts  and  reasoning. 

The  preceding  account  of  the  general  doctrines,  although  proba- 
bly sufficient  for  an  introduction,  is  far  from  being  complete,  and  ad- 
ditional illustrations  will  be  given,  when  the  proper  facts  come  in 
our  way. 

Before  proceeding  to  the  history  of  particular  bodies,  it  will  be 
useful  to  say  something  of  the  rules  of  philosophising,  and  of  the  ap- 
paratus and  operations. 

I.  RULES  OF  PHILOSOPHISING. — LIMITS  OF  HUMAN  REASON. 

1.    GOD    IS    THE    FIRST    CAUSE    OF    EVERY    THING. 

(a.)  Ml  our  observations,  experiments  and  reasonings,  make  us 
acquainted  only  with  second  causes* 

(b.)  Theproximate  cause  of  an  effect,  is  the  one  immediately  an^- 
tecedent  to  the  event,  or  which  is  principally  operative  in  produc- 
ing it. 

(c.)  To  every  proximate  cause,  there  may  be  another  proximate 
cause,  and  to  that  cause  another ;  but  the  series  will  end  at  last  in 
the  power  of  the  Creator,  in  immediate  agency  ;  and  this  will  still 
be  the  fact  if  we  discover  ever  so  many  proximate  causes,  constitu- 
ting a  series  or  chain  apparently  endless. 

(d.)  When  we  have  classified  similar  phenomena,  and  have  dis- 
covered their  modus  operandi ;  we  say  that  we  have  found  out  the 
law  that  governs  them  ;  but  still  this  harmony  of  facts  and  operations, 
we  must  trace  to  the  same  source. 


*  Am.  Jour.  Vol.  XVI,  p.  262,  and  Ann.  de  Chim.  et  de  Physique. 


174  ATTRACTION, 

(e.)  Natural  science  is  to  be  studied  by  observing  facts,  and  making 
experiments,  and  then  drawing  conclusions  ;  this  is  the  inductive  or 
Baconian  method  of  reasoning,  and  is  the  foundation  of  legitimate 
theory.  An  experiment  is  nothing  but  the  exhibition  of  a  fact. 

(f.)  Hypotheses  may  be  introduced  in  the  absence  of  true  theory 
founded  on  induction  ;  but  they  can  be  admitted  only  provisionally, 
until  something  better  can  be  done.* 

(g.)  We  will  add  from  Sir  Isaac  Newton,  that,  "  ive  are  to  admit 
no  more  causes  of  natural  things,  than  such  as  are  both  true  and  suffi- 
cient to  explain  their  appearances." 

(  h.)  "  Therefore,  to  the  same  natural  effects  we  must,  as  far  as 
possible,  assign  the  same  causes."^ 

(i.)  The  range  of  human  reason  is  the  whole  extent  of  second 
causes. 

(j.)  The  final  reason  of  a  particular  law  is  sometimes  discovered 
by  us,  and  always  magnifies  the  author.  The  unvarying  proportion 
of  oxygen  gas  in  the  atmosphere ;  and  the  means  by  which  it  is  pro- 
bably sustained ;  the  exception  in  the  expansion  of  water  between  32° 
and  40° ;  the  phosphorescence  of  marine  animals  and  of  fish  gener- 
ally in  the  ocean,  and  the  circulation  of  fluids  and  of  aeriform  bodies 
in  currents  to  equalize  temperature,  are  striking  instances  among  mul- 
titudes that  might  be  adduced. f 

(k.)  The  moral  effect  of  physical  study  upon  every  mind  which  has 
been  correctly  disciplined,  is  altogether  happy,  and  augments  the  vigor 
of  every  proper  feeling. — It  is  not,  however,  to  be  denied,  that  an  op- 
posite effect  is  sometimes  produced  upon  certain  minds ;  but  this  is 
the  fault  of  the  individual  and  not  of  the  study.  Even  moral  study 
sometimes  produces  the  same  effect. 

(/.)  The  greatest  mental  power  and  the  longest  life,  joined  with 
the  greatest  industry,  can  enable  man  to  compass  only  a  small  part  of 
universal  knowledge. — Of  this,  the  wisest  and  the  greatest  men  are 
the  most  sensible.  Newton  was  not  more  distinguished  for  his  vast 
powers  and  acquirements,  than  for  his  singular  modesty.  The  im- 
portant suggestions  at  the  end  of  his  optics  are  in  the  form  of  queries. 
The  whole  amount  of  the  knowledge  of  such  a  man,  compared  with 
all  that  a  savage  knows,  is  indeed  great ;  but,  compared  with  univer- 
sal knowledge,  it  is  an  evanescent  point. 

II.  APPARATUS  AND  OPERATIONS. 

Under  the  head  of  apparatus,  we  include  all  the  instruments  and 
utensils  employed  in  chemical  experiments. — An  experiment  being, 
(as  already  observed,)  only  the  exhibition  of  a  fact,  we  want  such 


*  See  Lord  Bacon's  Novum  Orgaiium,  and   Do  Augment.  Scientiarum. 
i  Principia,  Vol.  II,  Ed.  1803.  t  See  Paley's  Natural  Theology. 


ATTRACTION.  175 

instruments  as  will  enable  us  to  show  facts  ;  they  are  for  utility,  and 
not  for  mere  parade,  but  in  a  public  establishment,  elegance  may 
be  in  a  good  degree,  combined  with  utility. 

An  apparatus  is  best  explained,  when  it  is  used  ;  but  a  few  facts 
may  be  stated  advantageously  in  this  stage  of  our  progress,  and  the 
names  of  some  leading  instruments  and  operations  may  be  given. 

A  considerable  number  of  instruments  has  already  been  mention- 
ed, but  they  have  been  chiefly  those  which  illustrate  general  princi- 
ples, and  the  greater  part  have  been  very  intelligible.  For  private  re- 
search, and  for  the  instruction  of  only  a  lew  persons  at  once,  a  compli- 
cated and  expensive  apparatus  is  not  necessary.  Much  may  be  done 
by  cheap  and  simple  means. *  Still,  it  is  an  error  to  suppose  that  re- 
fined analysis  and  difficult  researches  that  demand  great  precision, 
can  be  accomplished  without  proper  instruments,  and  various  and 
sometimes  expensive  reagents  ;  nor  can  full  effect  be  given  before  a 
large  audience,  to  the  fine  experiments  with  which  chemistry 
abounds,  without  an  apparatus,  and  materials  corresponding  in  some 
measure,  to  the  splendor  and  dignity  of  the  subject. 

For  a  full  account  of  chemical  apparatus  and  operations,  the  stu- 
dent is  referred  to  Mr.  Faraday's  excellent  work  on  chemical  mani- 
pulations, where  all  the  information  that  can  be  desired  is  given. 

•Apparatus — names  of  things — heads  and  hints. — Instruments  of 
chemistry,  to  be  perfect,  should  be, 

(a.)  Transparent. 

Ib.)  Incapable  of  corrosion. 

(c.)  Incapable  of  fracture  by  heat  and  cold. 

( d.)  Strong  to  confine  elastic  vapors. 

(e.)  Not  liable  to  be  melted  or  otherwise  injured  by  heat. 

Glass,  metal,  and  earthen  ware,  collectively  possess  these  properties. 

Glass  has  the  two  first  characters,  in  a  sufficient  degree,  but  not  the 
rest; 

Metal,  has  sufficiently  the  third  an,d  fourth,  and 

Porcelain  or  earthen  ware,  the  fifth,  provided  the  heat  is  careful- 
ly managed. 

1.  Means  of  producing  heat. 

(a.)  Fuel,  fyc. — Charcoal,  coak,  anthracite  and  other  coals  ;  wood, 
oil,  alcohol,  ether,  hydrogen  gas  ;  this  gas  and  oxygen ;  friction,  per- 
cussion, fermentation,  chemical  mixtures. 

2.  Instruments  in  which,  and  means  by  which  the  application  is  to 
be  made. 


*  I  heard  Dr.  Priestly  say,  that  his  principal  instruments  were  gun  barrels,  glass 
tubes,  flasks,  vials  and  corks,  and  it  is  well  known  that  few  men  have  made  more 
discoveries.  Still  he  was  a  pioneer  ;  he  was  always  on  travels  of  discovery,  and  his 
operations  were  not  in  general  so  remarkable  for  refinement,  as  for  sagacity  and 
effect. 


176  ATTRACTION. 

(a.)  Furnaces,  Black's,  crucible  furnace,  table  furnaces,  Lewis', 
air  (furnaces,  forge  furnace.  The  general  principles  of  all  furnaces 
are  the  same.  The  principal  parts  are  an  ash  pit  and  register,  a 
grate,  a  body,  a  top,  and  a  chimney.  Argand's  lamp,  spirit  lamp, 
mouth  blowpipe,  table  blowpipe  or  Artists',  Dr.  Hare's,  compound 
and  hydrostatic,  electric  and  galvanic  apparatus,  and  burning  lenses, 
and  mirrors  are  useful  means  of  producing  heat. 

3.  Vessels  to  be  used  with  heat. 

(a.)  For  fusion. — Crucibles,  Hessian,  Wedgewood,  Austrian  or 
black  lead,  charcoal,  platinum,  gold,  silver. 

(b.)  For  mixture. — All  vessels  may  be  employed  for  these  pur- 
poses, provided  the  agents  do  not  act  on  them.  For  the  solution 
of  salts  in  the  cold,  most  vessels  will  answer ;  with  heat,  they 
must  bear  expansion  and  contraction.  For  metallic  solutions,  they 
must  generally  be  of  glass  or  earthen  ;  a  platinum  crucible  may 
however  be  employed  for  many  metallic  solutions. 

(c.)  For  evaporations,  distillations,  sublimations. — For  evapora- 
tion.— Earthen  pans,  glass  dishes,  watch  glasses,  saucers,  plates,  and 
porcelain,  and  metal  capsules ;  those  of  platinum  are  very  valuable  ; 
bottoms  of  retorts  and  mattrasses  are  useful.  Almost  all  vessels  an- 
swer for  crystallizations. 

For  distillations. — Common  still,  with  its  worm  and  refrigeratory, 
mattrasses,  oil  flasks,  tubulated  and  plain  retorts  and  receivers  of  glass, 
iron,  earthen  ware,  lead,  silver,  and  gold  or  platinum ;  bent  glass  tubes, 
closed  at  one  end. 

For  concentration,  decoction,  digestion. — Papin's  digester,  or  other 
strong  boiler  with  tubes  and  stop  .cocks  ;  occasionally,  almost  all  ves- 
sels are  used  for  boiling. 

(d.)  For  sublimation.-*- Most  of  the  vessels  last  named.  Baths  of 
writer,  sand,  ashes,  steam,  oil,  mercury,  hot  air,  alcohol,  brine,  &c. 
Alembics  of  glass,  metal,  &c. 

4.  PNEUMATIC  APPARATUS  AND  MISCELLANEOUS  ARTICLES. 

!a.)  Hydro-pneumatic  cistern  and  air  jars. 
b.)  Mercurial  trough,  usually  of  stone,  furnished  with  tubes  of 
glass. 

Sc.)  Air  pump  and  its  appendages.  Condensing  syringes. 
d.)  Gazometers  of  different  sizes  for  different  purposes.  Eudi- 
ometers and  graduated  glass  jars,  graduated  tubes,  detonating  tubes, 
Woulfe's  apparatus,  and  Dr.  Hare's  improvements ;  do.  for  impreg- 
nating with  carbonic  acid  gas.  Stands,  supports,  &c.  of  iron  and 
brass ;  barometer  and  thermometer ;  instruments  for  specific  gravity. 

5.  MECHANICAL  OPERATIONS  PREPARATORY. 

(a.)   Trituration. — Mortars  of  marble,  iron,  steel,  glass,  porcelain, 

jr,  porphyry,  agate,  wood,  granite. 
(b.)  Levigation. — The  rubbing  stone  and  muller. 
[c.)  Pulverization. — Rasps,  files,  graters,  hammers,  anvil. 


ATTRACTION.  J77 

d.)   Weighing. — Scales,  coarse  and  fine,  very  sensible  balances. 
e.)  Sifting. — Selves,  of  various  fineness,  with  andwithout  covers. 
/.)  Decantation. — Syphons,  coffee  pots,  &ic. 
g.)  Filtration. — Unsized  paper  of  various  quality,  pounded  glass, 
flannel,  filtering  stones,  sand,  &c.     Filtering  funnels  and  stands. 

6.  LUTES. 

Flour  and  water,  rye  paste ;  sand,  flour  and  clay  ;  fat  lute,  com- 
posed of  clay  and  oil,  lime  and  white  of  an  egg. 

7.  VESSELS  FOR  KEEPING  PRODUCTS. 

Ground  glass  stopped  bottles  for  deliquescent  salts  ;  wide  mouth- 
ed bottles ;  common  vessels  of  any  description.  Tin  cases  for  phos- 
phorus bottles. 

Drawers,  mineralogical  cabinet,  bladders  and  silk  bags,  for  the  pur- 
pose of  administering  gases. 

8.  LABORATORY — general  idea  of  one. — Any  convenient,  light,  dry, 
and  well  ventilated  place  for  the  performance  of  experiments.     Neat- 
ness, order,  and  care  of  one's  person  and  clothes  and  premises  are  in- 
dispensable. 

Necessity  of  caution  and  presence  of  mind.  Unreasonable  fears 
of  chemical  experiments.  Frequent  ventilation  of  a  laboratory  ne- 
cessary. 

Specific  gravity. 

The  specific  gravity  of  a  body  is  its  weight  under  a  given  volume. 
It  is  often  necessary  in  chemical  experiments,  to  take  the  specific 
gravity  of  bodies.  Ample  instructions  are  given  on  this  subject,  in 
every  book  of  Natural  Philosophy,  and  for  the  present,  mention  will 
be  made  only  of  its  application  to  gaseous  bodies. 

It  may  however  be  stated,  for  the  sake  of  those  who  have  not 
more  delicate  apparatus,  that  common  money  scales  are  sufficiently 
exact  for  most  purposes.  A  fragment  of  the  substance  to  be  weigh- 
ed, may  be  suspended  by  a  fine  thread  or  piece  of  sewing  silk,  from 
the  point  of  bearing  of  one  arm  of  the  balance,  the  thread  being 
long  enough  to  allow  the  fragment  to  swing  below  the  scale  so  as  to 
admit  of  immersion  in  pure  water  ;  we  then  proceed  as  is  usual  in 
similar  cases.  Dr.  Hare  has  several  ingenious  contrivances  and  in- 
ventions for  taking  specific  gravities,  which  may  be  seen  in  his  com- 
pendium, and  in  the  American  Journal  of  Science,  and  if  there  is 
room,  they  may  be  given  in  an  appendix  to  this  work. 

The  specific  gravity  of  fluids  is  easily  taken  by  weighing  them  in 
a  thin  vial  with  a  narrow  neck,  having  a  mark  upon  it  so  that  the  same 
volume  may  be  easily  taken ;  it  is  most  convenient  that  the  vial  should 
hold  1000  grains  of  distilled  water. 

23 


178 


ATTRACTION. 


Method  of  ascertaining  the  specific  gravities  of  the  gases. — Dr. 
Hare. 

"  Suppose  the  globe,  A, 
to  be  removed  from  the 
receiver,  R,  and  exhausted 
during  a  temporary  at- 
tachment to  an  air  pump, 
by  means  of  a  screw  with 
which  the  globe  is  fur- 
nished, and  which  serves 
also  to  fasten  it  to  the  re- 
ceiver, as  represented  in 
the  figure.  Being  pre- 
served in  this  state  of  ex- 
haustion, by  closing  the 
cock,  let  it  be  suspended 
from  a  scale  beam,  and 
accurately  counterpoised ; 
air  being  then  admitted, 
will  cause  it  to  preponde- 
rate decidedly.  If  in  lieu 
of  admitting  air,  the  globe 
be  restored  to  the  situation 
in  which  it  appears  in  this 
figure,  so  as  to  be  filled 
with  hydrogen  from  the 
receiver,  R,  anjl  after- 
wards once  more  sus- 
pended from  the  beam,  in- 
stead of  preponderating  de- 
cidedly, as  when  air  was 
allowed  to  enter ;  unless 
the  balance  be  very  deli- 
cate, the  additional  weight,  arising  from  the  admission  of  the  hydro- 
gen, will  scarcely  be  perceptible.  Supposing,  however,  that  the  ad- 
ditional weight  thus  acquired,  were  detected  ;  and  also  the  weight 
gained  by  the  admission  of  exactly  the  same  bulk  of  atmospheric  air, 
after  a  similar  exhaustion  of  the  globe,  the  weights  of  equal  volumes 
of  hydrogen  and  air,  would  be  represented  by  the  weights  thus  ascer- 
tained. The  specific  gravity  of  atmospheric  air  is  the  unit,  in  mul- 
tiples, or  fractions  of  which,  the  specific  gravities  of  the  gases  are  ex- 
pressed. Hence  the  weight  of  any  given  bulk  of  hydrogen,  divided 
by  the  weight  of  an  equal  bulk  of  air,  gives  the  specific  gravity  of 


ATTRACTION  179 

hydrogen.  By  a  similar  process,  the  specific  gravity  of  any  other 
gas  may  be  discovered." 

"  The  apparatus  for  ascertaining  specific  gravities,  above  represent- 
ed, is  that  which  is  recommended  by  Henry.  The  gas  may  be  more 
accurately  measured,  by  using  one  of  the  volumeters."* 

"  The  weight  of  any  given  number  of  cubic  inches  of  air  or  gas, 
as  one  hundred,  for  instance,  may  be  known  by  introducing  a  certain 
quantity  into  the  globe,  as  above  described,  and  noticing  the  acces- 
sion of  weight :  then,  as  the  number  of  cubic  inches  introduced,  is  to 
the  weight  gained  by  its  introduction,  so  is  one  hundred  to  the  weight 
of  one  hundred  cubic  inches  of  the  fluid." 

"  The  number  of  cubic  inches  introduced,  may  be  known  by  means 
of  the  graduation  on  the  receiver,  R." 

If  there  be  a  column  of  water  or  mercury  standing  in  the  jar,  the 
gas  will  be  less  compressed  than  if  there  were  no  such  column. 
Therefore,  the  density  will  be  inversely — the  volume  directly  as 
the  height  of  this  column.  Hence,  to  ascertain  the  volume,  say 
H  :  H  —  h'_  \v  :  x.  Here,  H  is  the  height  of  the  barometer,  h  the 
height  of  the  column,f  v  the  observed  volume,  and  x  the  volume  re- 
quired. 

In  weighing  the  gases  in  order  that  the  result  may  be  correct,  the 
gas  should  be  pure ;  it  should  be  dry,  or  due  allowance  should  be 
made  for  watery  vapor,  and  if  the  experiment  is  not  made  when  the 
barometer  is  at  30  inches,  and  the  thermometer  at  60°,  the  observ- 
ed volume  should  be  reduced  by  calculation,  to  what  it  would  be,  at 
the  medium  temperature  J  and  pressure. 

The  purity  must  be  secured  and  ascertained  by  the  modes  appro- 
priate to  each  particular  gas. 

Moisture  must  be  removed,  as  far  as  possible,  by  exposure  to  dry 
muriate  of  lime,  quick  lime  recently  ignited,  or  fused  potash ;  or  other 
substances  that  powerfully  attract  water. § 

For  temperature  ;  the  volumft  of  a  gas  is  as  the  temperature  direct- 
ly, and  as  operations  on  gases  are  almost  always  carried  on  above  32°, 
we  first  ascertain  the  volume  that  the  gas  would  occupy  at  that  tem- 
perature, which  is  done  by  multiplying  the  total  volume  by||  480, 
and  dividing  the  product  by||  480,  -f-  the  number  of  degrees  that  the 


*  See  Dr.  Hare's  Compendium. 

t  The  column  being  of  mercury,  or  due  allowance  made  if  it  is  water;  a  foot  of 
water  representing  nearly  an  inch  of  mercury. 

|  Gloves  should  be  worn  while  handling  the  vessels,  or  they  should  be  lifted  by 
the  keys  of  the  stop  cocks,  that  the  warmth  of  the  hands  may  not  cause  expansion  in 
the  gas. 

§  For  a  general  formula,  see  Henry,  6th  Ed.  Vol.  I,  p.  25,  and  Turner,  2d  Ed.  Vol. 
I,  p.  71. 

[|  Because  a  gas  expands  ^  j^  part  of  its  volume  by  every  degree  of  heat. 


180  ATTRACTION. 

temperature  is  above  32°  Fahr.  Then  to  determine  its  volume  at 
any  other  temperature,  "  add  T|¥  of  the  volume  at  32°,  for  each  de- 
gree that  the  temperature  required,  exceeds  32°  Fahr.  Thus,  to 
find  what  space  100  cubic  inches  of  gas  at  50°  would  occupy,  if 


raised  to  COo        _-%.4,   the   volume  at   32°,  and  96.4+ 

96.4X28  =  102  the      j  t  C0o»*_  Henry. 

480 

For  pressure  ;  the  volume  of  a  gas  is  inversely  as  the  pressure.  — 
To  reduce  the  volume  to  what  it  would  be  at  30  inches,  the  mean 
pressure,  "  as  the  mean  height  is  to  the  observed  height,  so  is  the 
observed  volume  'to  the  volume  required.  Suppose  the  barometer  to 
stand  at  29  inches,  and  that  we  wish  to  ascertain  what  volume  100 
cubic  inches  of  gas  would  occupy  at  30  inches,  30  :  29  :  1  100  :  96.66, 
which  last  number  is  the  answer  required. 

For  both  pressure  and  temperature.  —  Suppose  the  question  is,  what 
volume  would  100  cubic  inches  of  gas,  estimated  at  50°  of  Fahr. 
and  29  inches  of  the  barometer  occupy  at  60°  and  30  inches.  By 
first  correcting  the  temperature,  we  find  that  the  100  cubic  inches, 
would  be  102,  and  then,  30  :  29:  :  102  :  98.6. 

The  weight  of  a  given  volume  of  gas  being  known  at  any  temper- 
ature, to  learn  ivhat  would  be  the  weight  of  an  equal  volume  at  the 
mean  temperature.  —  The  volume  being  given,  the  weight  will  be  di- 
rectly as  the  pressure.  Correct  the  bulk  to  the  mean  temperature  ; 
"  then  say,  as  the  corrected  bulk  is  to  the  actual  weight,  so  is  the  ob- 
served bulk  to  the  number  required."  100  cub.  in.  of  gas  weighing 
50  grains  at  50°  Fahr.  would  at  60°  occupy  102  cub.  in.  and 
102  I  50:  :  100  :  49.02,  which  would  be  the  weight  of  100  cub.  in. 
at  60°. 

From  the  weight  of  a  given  volume  of  gas  at  an  observed  pressure, 
to  ascertain  what  would  be  its  weight  under  the  m,ean  pressure  ;  say, 
"  as  the  observed  pressure  is  to  the  mean  pressure,  so  is  the  observed 
weight  to  the  corrected  weight."  100  cub.  in.  of  gas  at  29  of  the 
barometer,  weight  50,  what  would  it  weigh  at  30  inches  pressure. 
29  !  30:  :50  :  51.72,  the  fourth  term  being  the  answer. 

To  combine  both  the  last  calculations.  —  100  cub.  in.  of  gas,  at  50° 
Fahr.  and  29  in.  pressure,  weight  50  grains,  what  would  it  weigh  at 
60°  Fahr.  and  30  inches  pressure  ;  first  make  the  correction  for 
temperature,  which  gives  for  the  weight  under  a  given  volume,  49.02, 
then,  29  :  30:  :  49.02  :  50.71,  which  is  the  answer  required,  f 


*  For  a  general  formula,  see  Turner,  2d  Ed.  p.  34. 

\  These  rules  are  cited  substantially  from  Henry,  10th  Ed.  Vol.  f,  p.  23 


ATTRACTION.  181 

Pneumatic   Cisterns. 

Dr.  Hales,  more  than  a  century  ago,  employed  an  apparatus  upon 
the  principle  of  the  modern  pneumatic  cistern,  which  was  introduced 
by  Dr.  Priestley.  This  instrument  is  little  else  than  a  vessel  suffi- 
ciently capacious,  filled  with  water  or  quicksilver,  and  furnished  with 
fixed  shelves  and  a  sliding  shelf.  The  apparatus  for  mercury  is  usu- 
ally small,  on  account  of  the  weight  and  expense  of  the  metal,  and 
ounce  measures  are  used  where,  in  the  other  apparatus,  we  employ 
quarts  or  gallons  of  water.  In  both,  for  the  purpose  of  expelling  the  air, 
the  vessels  are  filled  with  the  fluid,  and  then,  they  being  inverted  with 
their  mouths  under  it,  the  gas  is  introduced  from  below.  The  an- 
nexed cut  represents  the  mercurial  cistern  used  by  Dr.  Hare  ;  it  is, 
however,  five  or  six  times  larger  than  those  generally  employed. 
This  kind  of  cistern  is  rarely  used,  except  when  the  gases  are  rapid- 
ly absorbable  by  water.  That  in  the  laboratory  of  Yale  College,  is 
of  marble,*  and  of  a  similar  construction,  but  holds  not  over  two  hun- 
dred pounds  of  mercury,  and  usually  from  one  hundred  and  fifty  to- 
one  hundred  and  sixty  pounds. 

Mercurial  Cistern  for  gases. 
IB  - 


"  B  B,  is  a  wooden  box,  which  encloses  the  reservoir  so  as  to 
catch  any  of  the  metal  which  maybe  spilled  over  the  margin  of  the 
cistern.  This  box  is  bottomed  upon  stout  pieces  of  scantling,  tenant- 
ed together  and  grooved  so  as  to  conduct  the  mercury  towards  one 
corner,  where  there  is  a  spout  to  allow  it  to  escape  into  a  vessel,  situ- 
ated so  as  to  receive  it.  The  cistern  itself,  is  made  out  of  a  solid 
block  of  white  marble.  It  is  twenty  seven  inches  long,  twenty  four 
inches  wide,  and  ten  inches  deep." 

"  The  ledges,  S  S,  answer  for  the  same  purposes  as  the  shelves  in 
the  common  pneumatic  cistern.  The  excavation,  w,  is  the  well  in 
which  vessels  are  filled  with  mercury,  in  order  to  be  inverted  and 
placed,  while  full,  on  the  ledges.  There  are  some  round  holes  in 

*  Prof.  Hitchcock,  of  Amherst  College,  has  one  of  soap  stone. 


182  ATTRACTION. 

the  marble  for  introducing  upright  wires  to  hold  tubes,  or  Eudiome- 
ters ;  also  some  oblong  mortices,  for  allowing  the  ends  of  tubes,  duly 
recurved,  to  enter  under  the  edges  of  vessels  to  be  filled  with  gas  ; — 
and  in  cases  of  rapid  absorption,  to  afford  a  passage  for  the  mercury, 
into  vessels,  from  which  it  might  otherwise  be  excluded,  in  conse- 
quence of  their  close  contact,  with  the  marble  of  the  reservoir." 

"  This  reservoir  requires  nearly  six  hundred  pounds  of  mercury 
to  fill  it  completely." 

Water  ^cistern  for  gases. 

Any  vessel  containing  water  in  sufficient  depth  to  admit  of  filling 
the  air  glasses,  will  answer  in  some  good  degree.  There  is  in  the 
laboratory  of  Yale  College,  a  pneumatic  cistern  constructed  in  1803, 
of  which  an  engraving  was  given  in  the  editions  of  Henry's  Chemis- 
try published  by  me,  and  which  has  been  found  very  convenient.  It 
is  furnished  with  air  cells,  which  may  be  understood  by  an  inspec- 
tion of  Dr.  Hare's  figure  below.  In  mine,  there  were  only  the  up- 
per cells  here  represented  under  A  A,  but  divided  each  into  two 
compartments,  and  nearly  beneath  them  and  under  water,  were  hy- 
drostatic bellows,  for  throwing  in  air  and  gas.  From  the  cells,  also, 
proceeded  tubes  for  the  compound  blowpipe,  but  the  apparatus  in 
front,  representing  the  arched  tubes  and  the  inverted  kettle  and  its 
treadle,  and  also  the  other  lower  cells  under  C  C,  were  not  in  mine. 

Hydro-pneumatic  Cistern  of  Dr.  Hare. 


"  The  figure,  here  given,  is  such  as  would  be  presented  to  the  eye, 
were  the  front  of  the  cistern  removed." 

"  A  A,  are  two  shelves  formed  by  two  inverted  chests,  which  are 
used  as  cells  to  contain  gas :  B  is  a  sliding  shelf,  over  a  deep  place 
between  the  shelves,  A  A,  which  is  called  the  well  of  the  cistern." 


ATTRACTION,  183 

Fig.  2. 

"  Fig.  2  affords  a  view  of  the  lower  side 
of  the  sliding  shelf,  in  the  wood  of  which 
it  will  be  seen  that  there  are  two  excava- 
tions, converging  into  two  holes,  one  of 
which  is  seen  at  A,  fig.  1. — This  shelf  is 
loaded  with  an  ingot  of  lead  at  L,  to  prevent  it  from  floating  in  the 
water  of  the  cistern." 

"  Besides  the  chests  abovementioned,  there  are  two  others,  C  C, 
near  the  bottom  of  the  cistern,  but  not  so  close  as  to  prevent  the  wa- 
ter from  passing  freely  into  and  out  of  them." 

Referring  to  Dr.  Hare's  Compendium  for  the  remainder  of  the 
description,  I  will  add  only,  that  the  inverted  kettle  by  a  treadle  be- 
low, and  by  the  aid  of  a  peculiar  internal  construction,  is  made  to 
throw  in  air  through  the  lower  arched  tubes,  into  the  cells  under 
C  C,  which  are  intended  for  regulating  the  height  of  the  water ;  while 
it  is  allowed  to  escape  through  the  upper  arched  tubes  at  their  com- 
mon orifice  at/.  The  cells  under  A  A,  are  for  receiving  any  gas 
not  absorbable  by  water,  and  it  is  easily  drawn  off  at  the  cocks  at  e  e, 
into  vessels  standing  in  the  shelves  A  A. 

The  student  will  not  suppose  that,  strictly,  any  thing  more  is  ne- 
cessary for  a  pneumatic  cistern,  than  a  water  vessel  with  a  fixed  shelf 
or  shelves  as  at  A  A,  and  a  sliding  shelf  as  at  B,  and  even  the  latter 
may  be  dispensed  with  by  making  holes  through  one  of  the  fixed 
shelves,  and  introducing  an  inverted  funnel. 

GAZOMETERS. 

Gazometers  are  important  in  many  chemical  experiments.  In 
contriving  the  pneumatic  cistern  mentioned  above,  it  was  one  object 
to  furnish  gazometers  in  the  cistern  itself,  where  most  of  the  gases 
are  prepared  ;  and  there  was,  for  many  purposes,  great  utility  in  the 
contrivance  ;  but  the  gases  being  always  under  pressure,  were  of 
course  liable  to  escape  at  any  leak. 

There  is  so  much  convenience,  however,  in  occupying  with  air 
cells,  this  otherwise  useless  space,  that  I  should  still  recommend  this 
mode  of  construction,  of  the  pneumatic  cistern,  so  far  as  the  cells  are 
concerned  ;  without  attempting  any  thing  farther,  except  the  neces- 
sary appendages  to  draw  off  the  gases. 

On  the' whole,  I  have  found  the  most  useful  species  of  gazometer 
to  be  the  following,  which,  it  will  be  perceived,  is  only  a  modifica- 
tion of  the  form  generally  used. 

1.  The  containing  air  vessel  is  made  of  tinned  iron,  or  the  thin- 
nest sheet  copper,  painted  and  varnished  :  the  form  is  cylindrical,  as  at 


184 


ATTRACTION. 


1* 


A,  and  there  is  a  smaller  cylinder,  a,*  rising  in  the  centre  to  receive 
an  interior  gas  pipe  ;  the  rings  are  to  receive  the  cords  that  are  to 
suspend  the  cylinder  by  passing  over  pully  wheels  at  c  c,  fig.  2. 

2.  D  is  a  slightly  conical  cask,  to  be  filled  with  water  in  which  A 
is  suspended  by  the  cords  already  mentioned,  and  which  are  weight- 
ed at  d  d,  so  as  to  keep  the  air  vessel  in  equilibrio. 

3.  Fig.  3  represents  a  tube  of  copper  or  lead,  which  is  fastened 
within  the  cask  D,  so  that  the  limb  /  rises  in  the  center  and  passes  up 
into  a,  fig.  1,  when  the  air  vessel  is  down,  and  the  stop  cock  m  is 
open,  for  the  escape  of  the  common  air.     The  other  limb  e  is  fas- 
tened firmly  to  the  cask  at  the  side. 

4.  Fig.  4  represents  the  mouths  of  two  of  the  interior  tubes  with 
additional  tubes  fitted  air  tight,  with  corks  through  the  trumpet  shap- 
ed orifices,  i  i,  and  terminating,  after  curvature,  in  a  frustrum  of  pla- 
tinum at/.     This  apparatus  of  tubes  is  used  for  the  compound  or 
oxy-hydrogen  blowpipe  of  Dr.  Hare,  and  can  be  taken  off  by  double 
jointed  screws  at  o  o,  and  also  at  i  i,  and  any  other  apparatus  can  be 
attached.     At  b  6,  is  a  thin  slip  of  wood,  acting  both  as  a  guide  and 
a  scale  to  the  air  vessel. 

It  is  obvious  that  if  there  are  two  casks  and  two  air  vessels,  they 
will  form  convenient  reservoirs  for  oxygen  and  hydrogen.  Mine 
contain  together  fifty  gallons,  and  by  means  of  weights  laid  on  the  air 
vessels,  the  gases  are  made  to  issue  at  j9  with  all  necessary  force. 
Nothing  can  be  more  convenient  for  the  compound  blowpipe  ;  for  the 
oxygen  or  the  hydrogen  blowpipe  alone ;  for  the  common  air  blowpipe ; 
for  gas  lights ;  for  musical  tones  with  hydrogen ;  for  communicating 
oxygen  and  hydrogen  through  a  tube  to  the  pneumatic  cistern,  and 
for  many  other  purposes,  sufficiently  obvious  to  a  practical  chemist. 
Smaller  instruments  upon  this  principle,  are  convenient  for  the  respi- 
ration of  gases,  a  proper  mouth  piece  being  fitted  to  e  g,  fig.  3. 


Which  may  be  furnished  with  a  small  stop  cock,  to  let  off  common  air. 


OXYGEN.  185 

PART  IL—  PONDERABLE  BODIES. 

Introductory  Remark. 

I  SHALL  here  repeat  what  was  stated  in  the  Introduction,  p.  18, 
that  a  real  element  is  an  undecomposable  body  ;  that,  in  relation  to 
our  knowledge,  an  element  is  merely  an  undecomposed  body. 

Our  evidence  on  this  subject  being  only  negative,  it  follows  that 
any  body  and  all  bodies,  now  admitted  as  elementary,  may  hereafter 
be  decomposed. 

Should  we,  for  argument's  sake,  admit  the  improbable  result,  that 
all  compound  bodies  may  be  hereafter  reduced  to  two,  the  smallest 
number  of  principles  with  which  it  is  possible  to  form  a  third  body, 
we  should  even  then  not  be  certain,  that  these  two  were  real  ele- 
ments ;  for  they  might  be  decomposed  into  two,  three,  or  four  others, 
and  they  again  into  five,  six,  seven,  or  eight  others,  and  so  on  ;  pro- 
ceeding from  the  greatest  apparent  simplicity,  to  the  greatest  com- 
plexness. 

It  is  proper  to  recal  to  the  recollection  of  the  student,  that  the  an- 
cient hypothetical  elements,  earth,  air,  fire  and  water,  have  all  been 
proved  to  be  compound,  and  that  there  are  now  more  than  fifty*  un- 
decomposed bodies,  among  which  are  three  supporters  of  combustion, 
oxygen,  chlorine  and  iodine  ;  about  forty  metals,  and  seven  combusti- 
bles, that  are  not  metallic,  namely,  phosphorus,  carbon,  hydrogen,  sul- 
phur, nitrogen,  boron  and  selenium.  Nitrogen,  as  already  observed, 
is  thrown  into  this  class,  as  resembling  them  very  much  in  its  relations 
and  character,  although  it  is  not  in  the  popular  sense  a  combustible. 

INORGANIC  BODIES. 
SIMPLE  SUPPORTERS  OF  COMBUSTION. 

SEC.  I.    OXYGEN. 


1.  NAME,  Oxygen^  derived  from  ogus  and  ysivopat  or  /svvaw,  signi- 
fying, therefore,  the  generator  of  acids  ;  a  name  imposed  by  the 
framers  of  the  new  nomenclature  ;  the  former  names  were,  dephlo- 

*  Dr.  Turner's  2d  edition,  gives  fifty  two,  including  bromine  and  selenium. 

t  Several  authors,  (as  Thenard,  5th  Ed.  Vol.  I,  p.  166,)  consider  the  name  oxygen 
as  improper,  because  it  is  not  the  sole  acidifier  ;  but  it  is  the  great  ruling  acidifier,  it 
being  the  sole  agent  in  almost  all  cases,  and  therefore  the  name  is  proper.  We 
might  as  well  reject  the  name  chlorine,  because  it  is  not  the  only  greenish  yellow 
body. 

24 


186  OXYGEN, 

gisticated  air,  vital  air,  empyreal  or  fire  air,  and  pure  air,  which  have 
all  yielded  to  the  name  oxygen. 

2.  PROCESSES. 

(a.)  There  are  several ;  the  most  useful  is  by  igniting  the  purest* 
black  oxide  of  manganese  in  an  iron  bottlef  or  earthen  retort ;  one 
ounce  of  the  oxide  affords  about  one  hundred  and  twenty  eight  cubic 
inches  of  gas. 

(6.)  Sulphuric  acid  1  part,  mixed  with  the  same  mineral  2  parts, 
to  the  consistence  of  a  paste,  and  heated  moderately,  affords  this 
gas  ;  the  theory  of  these  experiments  will  be  given  hereafter. 

(c.)  Other  modes  will  be  mentioned  farther  on,  such  as  that  of 
heating  the  chlorate  or  nitrate  of  potash,{  or  a  mixture  of  red  lead 
and  sulphuric  acid ;  and  that  from  green  leaves  placed  in  water  in 
the  sun's  light,  &c.  The  gas  is  received  in  inverted  glasses  full  of 
water. 

3.  DISCOVERY — 

(a.)  By  Dr.  Priestley,^  in  England,  August,  1774,  by  heating 
red  oxide  of  mercury,  in  a  bell  glass  by  the  solar  focus. 

(6.)  By  Scheele,  in  Sweden,  the  year  after,  and  without  a  knowl- 
edge of  Dr.  Priestley's  discovery ;  and  also  by  Lavoisier,  at  Paris,  in 
the  same  year. 

4.  PHYSICAL  PROPERTIES. 

(a.)  Transparent,  colorless,  tasteless,  inodorous,  not  condensible 
by  pressure  and  cold,  a  non-conductor  of  electricity. 


(b.)  Sp.  gr.  1.1111,  air  being  1. — Thomson. 
(c.)  Wei^ 


ight  33.8888  for  100  cub.  in.  at  the  medium  temperature 
and  pressure. — Id. 

(d.)  Refracts  light  less  powerfully  than  any  other  gas. 

(e.)  Becomes  luminous ||  as  well  as  hot,  by  sudden  condensation. 

(/.)  It  is  a  non-conductor  of  electricity. 

5.  CHEMICAL  PROPERTIES. 

(a.)  It  possesses  more  extensive  powers  of  combination  than  other 
substance. 


*  It  is  sometimes  previously  washed  with  a  weak  mineral  acid,  to  decompose  car- 
bonate of  lime,  if  any  is  present. 

t  A  wrought  iron  bottle,  with  a  wide  tube  about  two  feet  long  welded  to  it,  is 
much  the  best  instrument ;  it  should  be  coated,  every  time  it  is  used,  with  a  lute  of 
clay,  sand,  and  flour,  applied  with  the  hand  and  dried  before  using.  A  gun  barrel 
answers  for  a  small  experiment. 

t  Dr.  Thomson  says  that  the  first  5th  of  the  gas  from  nitre  is  quite  pure,  and  Dr. 
Hare  confirms  the  statement,  that  the  first  portions  are  quite  pure. 

§  See  Priestley's  account  in  his  work  on  air. 

||  All  the  gases  become  hot  by  sudden  pressure,  but  chlorine  and  oxygen  are  the 
only  simple  gases  that  become  luminous  in  this  manner ;  common  air  becomes 
luminous  by  the  same  treatment,  but  in  a  less  degree  than  oxygen,  to  which  gas, 
this  property  in  air  is  owing. 


OXYGEN.  187 

(B.)    IT    ACTS    ON    COMBUSTIBLE    BODIES  WITH  INTENSE  ENERGY, 

and  this  is  one  of  its  great  characteristic,  but  not  altogether  peculiar 
properties. 

(c.)  Generally  the  temperature  must  be  raised,  in  order  to  bring 
on  the  action. 

(d.)*  A  lighted  candle  burns  brilliantly  in  oxygen  gas.  If  extin- 
guished, (fire  remaining  on  the  wick,)  it  is  instantly  relighted  with  a 
slight  report,  and  that  many  times  in  succession,  j- 

Candle  in  air,  in  vacuo,  and  in  oxygen  gas. — Dr.  Hare. 


"  Let  there  be  two  bell  glasses,  A  and  B,  communicating  with 
each  other  by  a  flexible  leaden  pipe,  a  cock  intervening  at  C. — Sup- 
pose A,  to  be  placed  over  a  lighted  candle  on  the  plate  D,  which 
communicates  with  an  air  pump  plate  as  represented  at  E. — It  will 
be  found  that  the  candle  will  gradually  burn  more  dimly,  and  will  at 
last  go  out,  if  no  supply  of  fresh  air  be  allowed  to  enter  the  contain- 
ing bell ;  if  on  repeating  the  experiment,  the  air  be  withdrawn  by 
means  of  the  pump,  the  candle  is  rapidly  extinguished.  It  is  thus 
demonstrated,  that  a  candle  will  not  burn  in  vacuo,  and  that  it  can 
burn  only  for  a  limited  time,  in  a  limited  portion  of  atmospheric  air." 

"  Let  the  experiment  be  repeated  with  the  following  change.  Let 
the  air  be  exhausted  from  both  vessels,  the  cock,  C,  remaining  open, 

*  For  the  experiments  under  d  and  /,  a  common  glass  bottle  answers  suf-  n 
ficiently  well. 

t  A  quart  of  oxygen  gas,  well  managed  in  a  bottle,  will  relight  a  candle 
more  than  fifty  times ;  the  bottle  should  be  held  mouth  upwards,  and  gent- 
ly inclined  each  time  the  candle  wick  is  presented  to  it ;  as  the  oxygen  is 
consumed  or  expelled,  the  bottle  must  be  turned  down  more  and  more.  A 
candle  in  a  socket,  fixed  to  a  wire,  is  easily  let  down  into  a  jar  of  gas,  as  rep- 
resented in  the  cut. 


188 


OXYGEN. 


until  the  bell,  B,  is  filled  with  water  from  the  shelf  of  the  pneumatic 
cistern,  on  which,  for  this  experiment,  it  must  be  placed.  The 
cock  being  closed,  fill  the  bell,  last  mentioned,  with  oxygen  gas,  from 
the  cell  of  the  cistern.  Now  lift  the  bell  A,  which  may  be  easily 
done,  the  pipe  having  a  due  flexibility,  and  introducing  a  candle,  set 
the  bell  again  on  the  plate.  Next  exhaust  the  air  until  the  candle 
is  nearly  extinguished,  and  then  open  the  cock,  so  as  to  allow  the 
oxygen  to  enter. — The  candle  will  now  burn  brilliantly  for  a  much 
longer  time,  than  it  had  done,  when  the  bell  contained  atmospheric 
air." 

(e.)  Ignited  charcoal  burns  intensely  in  this  gas,  and  the  bark  with 
vivid  scintillations. 

(f.)  Iron  wire  or  a  watch  spring,  with  a  lighted  sulphur  match  on 
the  end,  burns  with  bright  ignition  and  sparks,  but  without  flame. 

Combustion  of  iron  wire  in  oxygen  gas. — Id. 

11  Place  over  the  cock  of 
one  of  the  cells  of  the  pneu- 
matic cistern,  sufficiently 
supplied  with  oxygen  gas,  a 
glass  vessel,  such  as  is  usu- 
ally employed  to  shelter  can- 
dles from  currents  of  air. 
Let  the  upper  opening  of 
the  vessel  be  closed,  by  a 
lid  with  a  central  circular 
aperture,  as  here  represent- 
ed. Leaving  this  aperture 
open,  by  turning  the  key 
of  the  cock,  allow  the  gas 
to  rise  into  the  vessel  from 
the  cell.  Next  apply  a  ta- 
per to  the  aperture,  and  as 
soon  as  it  indicates  by  an  in- 
creased brilliancy  of  com- 
bustion, that  oxygen  has 
taken  place  of  the  air  pre- 
viously in  the  vessel,  cover 
the  aperture.*  Wind  a  fine 
wire  round  any  hard  cylin- 


*  Or,  any  vessel,  large  or  small,  may  be  rilled  with  oxygen  gas,  by  simply  con- 
veying the  orifice  of  a  curved  tube  to  the  bottom  of  the  vessel,  the  other  end  of  the 
tube  being  connected  with  a  gazometer  or  other  reservoir,  from  which  the  gas  is 
allowed  to  flow  ;  the  atmosphere  is  thus  lifted  out  and  the  oxygen  takes  its  place. 


OXYGEN.  189 

drical  body  of  about  an  inch  in  diameter.*  By  these  means,  the  wire 
is  easily  made  to  assume  the  form  of  a  spiral.  Near  the  end  of  the 
spiral,  wind  it  about  a  piece  of  spunk  about  as  large  as  a  pin.  Hav- 
ing lighted  the  spunk,  remove  the  cover  from  the  aperture  in  the  lid 
of  the  vessel,  and  lower  the  end  of  the  wire  to  which  the  spunk  may 
be  attached,  into  the  oxygen  gas.  The  access  of  the  oxygen  causes 
the  spunk  to  be  ignited  so  vividly,  that  the  wire  takes  fire  and  burns 
with  great  splendor,  forming  a  brilliant  liquid  globule,  which  scintil- 
lates beautifully.  This  globule  is  so  intensely  hot,  that  sometimes  on 
falling,  it  cannot  immediately  sink  into  the  water  ;  but  leaps  about  on 
the  surface,  in  consequence  of  the  steam  which  it  causes  the  water 
to  emit.  If  it  be  thrown  against  the  glass  of  the  containing  vessel, 
it  usually  fuses  it  without  causing  a  fracture,  and  has  been  known  to 
pass  through  the  glass,  producing  a  perforation  without  any  other 
injury." 

(g.)  A  stream  of  oxygen  gas  from  a  gazometer  and  blowpipe,  di- 
rected upon  burning  charcoal,  melts  and  burns  many  bodies,  as  iron, 
copper  and  tin,  with  brilliant  appearances,  and  the  evolution  of  much 
heat. 

(H.)  EFFECT  OF  THE  COMBUSTION. 

The  oxygen  gas  is  diminished  ;  its  ponderable  part  combines  with 
the  combustible  body,  and  both  changes  its  properties  and  increases  its 
weight;  one  grain  being  gained  in  weight  for  every  three  cubic 
inches  of  gas  absorbed.  Combustibles,  which  like  oil,  candles,  and 
charcoal,  disappear  while  burning,  are  not  destroyed  ;  they  have  only 
passed  off  in  gas,  and  other  diffused  forms ;  with  proper  care,  all 
the  products  can  be  collected  again ;  we  can  neither  create  nor  an- 
nihilate an  atom. 

(i.)  Products  of  the  combination. — They  are  either  acids,  alkalies, 
oxides  or  earths  ;  the  three  last  may  strictly  be  included  under  one 
head,  but  it  is  convenient  to  divide  them.  The  process  of  combin- 
ing with  oxygen,  is  called  oxidation  or  oxidizement,  and  the  corres- 
ponding verb  is  oxidate  or  oxidize.-^  The  oxides  are  sometimes  dis- 
tinguished by  terms  derived  from  their  colors,  but  Dr.  Thomson  has 
introduced  a  nomenclature  founded  on  the  Greek  numerals,  as  pro- 
toxide, deutoxide,  tritoxide,  viz.  first,  second,  and  third  oxide,  &c. 
and  Jperoxide,  for  the  oxide  with  the  most  oxygen. 

(j.)  Water,  at  the  pressure  of  30  inches,  and  temperature  60°,  if 
freed  from  air  by  boiling,  absorbs  3.5  cubic  inches  of  oxygen  gas, 
for  every  100  cubic  inches  of  water;  by  pressure,  the  quantity  is  in- 


*  I  use  a  ram  rod  and  binding  wire. 

t  Some  use  oxygenize  or  oxygenate,  oxygenizement  or  oxygenation ;  these  terms 
are  rather  more  genera),  and  do  not  decide  whether  the  product  is  an  oxide  or  an 
acid.  t  From  the  Latin  preposition. 


190  OXYGEN 

creased,  and  by  great  pressure,  water  will  absorb  half  its  bulk,  but 
without  any  change  of  properties. 

6.  Relation  to  animal  life. 

(a.)  Oxygen  supports  life  eminently  in  respiration,  and  is  the  only 
agent  that  is  adapted  to  this  purpose ;  but  it  is  necessary  that  its 
great  energy  should  be  mitigated  by  dilution,  as  will  be  mentioned 
again  farther  on. 

(b.)  A  bird  will  live  five  or  six  times  as  long  in  a  confined  portion 
of  oxygen  gas,  as  in  the  same  volume  of  common  air  ;  and  several 
birds  will  live  a  short  time  in  oxygen  gas,  in  which  others  have  died ; 
each  successive  one  will,  however,  in  general,  live  a  shorter  time 
than  its  predecessor. 

"  Count  Morozzo  placed  a  number  of  sparrows,  one  after  another, 
in  a  glass  bell  filled  with  common  air,  and  inverted  over  water  : — 
The  first  sparrow  lived       -  -       3^.  Om. 

The  2d         "         "      -  -  03 

The  3d         "         "  -       0     1 

"  The  water  rose  in  the  vessel,  eight  lines  during  the  life  of  the 
first ;  four  during  that  of  the  second,  and  the  third  produced  no  ab- 
sorption. He  filled  the  same  glass  with  oxygen  gas,  and  repeated 
the  experiment. 

The  first  sparrow  lived       -         -  5h.  23m. 

The  2d       "          "     -  -  2     10 

The  3d       «          "  1      30 

The  4th       «          «     .  -   1      10 

The  5th       "          "  -       0     30 

The  6th       «          «     -  -  0     47 

The  7th       "          "  0     27 

The  8th       "          «     -  -  0     30 

The  9th       "          "  0     22 

The  10th     "          "     -  -  0     21 

He  then  put  in  two  together,  the  one  died  in  twenty  minutes,  but 
the  other  lived  an  hour  longer." — Chaptaland  Thomson. 

7.  Relation  to  disease.— Oxygen  gas  is  eminently  salutary  in  some 
cases,  especially  in  diseases  of  the  thorax,  in  paralysis,  general  de- 
bility, &c.* 

*  Oxygen  gas,  when  respired  in  the  human  lungs,  generally  produces  a  sen- 
sation of  agreeable  warmth  about  the  region  of  the  chest,  and  some  say  that  they  ex- 
perience a  comfortable  sensation  through  the  whole  body.  Chaptal  relates  the  fol- 
l^wing  instance  of  its  effects  on  a  man  in  consumption.  "  Mr.  De  B."  says  this 
writer,  "  was'  in  the  last  stage  of  a  confirmed  pthisis.  Extreme  weakness,  profuse 
sweats,  and  in  short,  every  symptom  announced  the  approach  of  death.  One 
of  my  friends,  Mr.  De  P ,  put  him  on  a  course  of  vital  air.  The  patient  respir- 
ed it  with  delight,  and  asked  for  it  with  all  the  eagerness  of  an  infant  at  the  breast. 
During  the  time  that  he  respired  it,  he  felt  a  comfortable  heat  which  distributed  it- 
self through  all  his  limbs.  His  strength  increased  with  the  greatest  rapidity ;  and 


OXYGEN  191 

8.  Effect  on  the  color  of  the  blood. — If  blood  be  suspended  in 
oxygen  gas  or  agitated  with  it,  or  even  with  common  air  in  a  glass 
tube,  it  turns  it  of  a  brilliant  vermilion  color;  the  nature  of  the 
change  is  to  be  mentioned  hereafter  more  particularly  ;  we  may  how- 
ever remark  at  present,  that  it  acts  on  the  blood  principally,  by  im- 
parting oxygen  and  detaching  carbon. 

9.  It  is  found  in  more  combinations  and  in  greater  quantities  than 
any  element.* — It  is  found  in  the  atmosphere,  in  all  waters  and  watery 
fluids,  and  in  all  natural  fluids,  except  perhaps  naptha  and  mercury. 
It  exists  in  animals  and  plants;  in  stones,  rocks,  and  metallic  oxides, 
and  in  acids,  salts,  earths,  and  alkalies ;  it  possesses  therefore  the 
highest  importance,  and  without  knowing  this  agent,  we  could  under- 
stand little  of  the  real  constitution  of  things. 

What  has  been  called  the  modern  theory  of  chemistry,  was 
occupied  principally  in  unfolding  the  agencies  of  oxygen,  and  this 
exposition  still  constitutes  the  most  important  part  of  the  science. 

10.  Polarity. — It  goes  to  the  positive  pole  in  the  electro-galvanic 
circuit,  and  is  therefore  considered  as  electro-negative. f 

11.  Its  combining  weight. — Hydrogen  being  unity, J  oxygen  is 
represented  by  8,  because  these  are  the  proportions  in  which  these 
elements  exist  in  water. 

As  its  combining  weight  is  "  smaller  than  that  of  most  bodies,  it  is 
inferred  that  it  approaches  nearer  than  they  to  the  elementary  or 


in  six  weeks,  he  was  able  to  take  long  walks.  This  state  of  health  lasted  for  six 
months  ;  but  after  this  interval  he  relapsed ;  and  being  no  longer  able  to  have  re- 
course to  the  use  of  vital  air,  because  Mr.  De  P had  departed  for  Paris,  he 

died.  I  am  very  far,  adds  Mr.  Chaptal,  from  believing  that  the  respiration  of  vital 
air  ought  to  be  considered  as  a  specific,  in  cases  of  this  nature.  I  am  even  in  doubt 
whether  this  powerful  air  is  perfectly  adapted  to  such  circumstances ;  but  it  in- 
spires cheerfulness,  renders  the  patient  happy,  and  in  desperate  cases,  it  is  certainly 
a  most  precious  remedy,  which  can  spread  flowers  on  the  borders  of  the  tomb,  and 
prepare  us  in  the  gentlest  manner  for  the  last  dreadful  effort  of  nature." 

Thenard  relates  that  of  three  men  who  had  been  suffocated  by  sulphuretted  hy- 
drogen gas,  in  cleaning  a  privy,  two  died  almost  immediately,  and  the  third  being 
almost  dead,  was  made  to  respire  oxygen  gas  from  a  bladder,  and  it  rallied  his  pow- 
ers so  that  he  sat  up  for  a  moment,  but  soon  fell  back  and  died.  In  a  case  related  in 
the  Am.  Jour.  Vol.  XVI,  p.  250,  by  Dr.  Muse,  of  Cambridge,  Maryland,  there  was 
the  most  complete  success,  a  favorite  hound  that  had  been  for  several  hours  com- 
pletely drowned,  having  been  perfectly  restored  to  life,  and  gradually  to  all  his  func- 
tions in  consequence  of  the  injection  of  oxygen  gas  into  his  lungs  ;  the  very  first  in- 
flation of  the  lungs  produced  a  shrill  yelp  from  the  animal.  For  other  remarkable 
cases,  see  also  Am.  Jour.  Vol.  I,  p.  95,  and  Dr.  Thornton's  various  Reports  in  Til- 
loch's  Philos.  Mag. 

*  Limiting  our  estimate,  of  course,  to  the  bodies  with  which  we  are  acquainted^ 
t  Several  respectable  modern  authors  make  this  fact  the  foundation  of  an  arrange- 
ment of  chemical  bodies. 

t  Several  authors  have  adopted  oxygen  for  unity ;  Dr.  Thomson  makes  it  1,  Dr, 
Wollaston  10,  Berzelius  100,  &c. 


192  OXYGEN. 

simple  state  ;"*  this  might  have  been  said  with  still  greater  truth,  of 
carbon  and  hydrogen. 

Remarks. 

Oxygen  unites  with  every  simple  body,  but  it  has  neither  acid  nor 
alkaline  properties.  It  is  the  agent  in  all  common  cases  of  combus- 
tion, which  in  most  instances,  is  nothing  more  than  rapid  oxidation, 
with  the  emission  of  heat  and  light ;  and  a  slow  combination  of  ox- 
ygen often  goes  on  without  either ;  common  iron  rust  is  produced  in 
that  manner. 

Combustion  and  respiration  have  the  same  effect  in  vitiating  the 
air ;  the  air  in  which  an  animal  has  died,  will  not  support  combus- 
tion, and  the  air  in  which  a  combustible  will  not  burn,  will  not  sup- 
port animal  life. 

Oxygen  is  involved  in  the  chemical  study  of  all  bodies,  simple 
and  compound.  The  term  oxygen  means  strictly  the  ponderable 
part  of  oxygen  gas  ;  the  material  part  is  known  only  in  combination  ; 
it  has  never  yet  been  isolated  so  as  to  exhibit  it  separately ;  in  its 
gaseous  form,  it  is  combined  with  caloric  and  light,  and  probably 
with  electricity. 

It  appears  to  exist  no  where  in  nature,  in  a  pure  and  disengaged 
state,  and  we  always  obtain  it  for  use  by  evolving  it  from  one  of  its 
combinations.  Healthy  leaves  of  vegetables,  acted  upon  by  the  di- 
rect sun  beams,  throw  it  off  incessantly  into  the  atmosphere,  and  it 
is  supposed  to  be  a  principal  means  of  recruiting  the  waste  of  oxygen 
which  arises  from  combustion,  respiration,  and  other  natural  processes. 
In  the  dark,  a  different  gas,  the  carbonic  acid  is  said  to  be  disengag- 
ed ;  the  subject  will  be  resumed  in  giving  the  history  of  that  gas. 

It  is  fortunate  that  oxygen  gas  can  be  easily  and  abundantly  ob- 
tained from  the  native  oxide  of  manganese,  as  there  is  scarcely  any 
other  from  which  it  could  be  obtained  at  all,  and  no  other  which 
could  supply  the  demands  of  chemistry  and  the  arts. 

Nitre  is  perhaps  the  easiest  resource  for  affording  oxygen  gas,  but 
only  the  early  portions  are  pure ;  a  little  may  be  heated  to  low  red- 
ness in  a  gun  barrel,  but  we  should  avoid  the  mouth,  as  the  melted 
nitre  is  apt  to  boil  up,  congeal  above  the  ignited  portion  of  the  tube, 
and  thus  acting  like  a  wad,  by  and  by,  after  a  cessation,  the  gas  causes 
an  explosion,  by  which  the  hot  nitre  is  driven  about.  Every  thing 
connected  with  the  history  of  oxygen,  is  elegant,  beautiful,  and  in- 
structive ;  without  it  there  would  be  no  beginning  of  animal  life,  nor 
any  adequate  means  of  producing  and  regulating  heat. 


*  Murray,  Vol.  I,  p.  407. 


NITROGEN. 

SEC.  II.     NITROGEN  OR  AZOTE. THE  ATMOSPHERE. 

NITROGEN. 

1.  Name. — As  it  is  the  basis  of  nitric  acid,  it  is  now  called  nitro- 
gen ;    its  former  name  was  from  a,   a  Greek  privative,    and   £w?j, 
life,  signifying  that  which  destroys  life  ;  but  the  name  is  not  distinc- 
tive, many  other  gases  being  azotic. 

2.  Discovery — by  Dr.  Rutherford,  at   Edinburgh,  1772  ;  Lavoi- 
sier first  separated  it  from  the  atmosphere,  in  1775,  and  Scheele, 
about  the  same  time. 

3.  Mode  of  obtaining. 

(a.)  Burn  phosphorus  in  a  floating  saucer  or  other  earthen  dish 
under  a  bell  glass  over  water ;  the  acid  fumes  are  absorbed  in  half 
an  hour  by  the  water,  and  sooner,  if  agitated  with  it ;  and  nitrogen 
gas  slightly  phosphorized,  remains. 

Solution  of  caustic  potash,  agitated  with  the  gas  in  a  bottle,  quickly 
separates  both  the  phosphoric  acid,  and  a  little  carbonic  acid  which 
is  sometimes  mingled  with  it. 

(b.)  With  a  gentle  heat,  dilute  nitric  acid,  sp.  gr.  1.20,  acting  on 
lean  muscle  in  a  glass  retort,  evolves  nitrogen. 

(c.)  Iron  filings  and  sulphur  being  mixed  and  moistened,  and  placed 
in  a  saucer  under  a  bell  glass ;  the  oxygen  is  absorbed  in  three  or 
four  days,  and  nitrogen  remains.  Other  methods  will  be  mentioned 
farther  on. 

4.  PHYSICAL  AND  CHEMICAL  PROPERTIES. 

(a.)  Transparent,  colorless,  inodorous,  tasteless,  not  sensibly  ab- 
sorbed by  water. 

(b.)  Sp.  gr.  .9722,  air  being  1.— (Thomson.)  100  cub.  in.  weigh 
29,652  grains. 

(c.)  Its  refractive  power  is  very  feeble. 

(d.)  Combines  with  oxygen,  and  forms  several  very  important 
compounds — nitric  acid,  the  nitrous  acids,  nitric  oxide  gas,  and  ni- 
trous oxide  gas. 

(e.)  No  combination  results  from  a  mere  mixture  of  the  oxygen 
and  nitrogen  ;  owing  to  the  repelling  power  of  caloric,  they  would 
probably  remain  forever  in  mixture,  without  change  ;  but  they  will 
unite,  if  in  the  nascent  state,  or,  if  one  of  them  is  in  that  condition. 

(f.\  Combined  with  oxygen  by  electricity,  nitrogen  forms  nitric  acid.. 

(jr.)  Still  it  is  not  a  combustible  in  the  common  sense  of  that  word  ? 
it  does  not  fire  by  the  approach  of  a  candle  to  the  mouth  of  a  vessel 
containing  it,  nor  if  previously  mixed  with  oxygen  gas. 

(h.)  It  is  fatal  to  combustion. — A  burning  match,  candle,  phos- 
phorus, or  any  burning  body  is  extinguished  by  immersion  in  this 

25 


194  NITROGEN. 

gas  ;  even  potassium,  although  intensely  heated  by  galvanism  in  nitro- 
gen, produces  no  change  ;  it  is  therefore  not  a  supporter  of  combus- 
tion. 

(i.)  Water  deprived  of  its  air  by  boiling,  absorbs  about  one  and  a 
half  per  cent,  of  this  gas  ;  or,  according  to  Dr.  Ure,  100  volumes  of 
water  absorb  about  one  of  this  gas  ;  Mr.  Dalton  states  it  at  2.5. 

5.  EFFECTS  ON  ANIMAL  LIFE. 

(a.)  Fatal,  if  breathed  pure  ;  an  animal  immersed  in  it,  immedi- 
ately dies. 

(6.)  Kills  by  suffocation  merely  ;  it  is  not  directly  noxious,  and  ex- 
erts no  positively  injurious  influence  on  the  lungs;  an  animal  is  drown- 
ed in  it  as  it  would  be  in  water. 

6.  COMPOSITION. 

(a.)  Unknown;  but  it  is  suspected  to  be  compound;  Berzelius 
believes  it  to  be  an  oxide  of  an  unknown  base.* 

(b.)  Contained  in  animal  matter,  and  is  equally  abundant  in  her- 
bivorous and  graminivorous,  as  in  carnivorous  animals. 

(c.)  Plants  do  not  generally  contain  it. 

(d.)  It  is  an  element,  according  to  the  present  state  of  our  knowl- 
edge.! 

7.  IMPORTANCE  AND  DIFFUSION. 

(«.)  It  forms  the  basis  of  animal  substances  ;  of  them  it  is  the  char- 
acteristic element,  and  it  gives  origin  to  the  ammonia  and  the  prus- 
sic  acid,  which  are  generated  during  their  decomposition. 

(6.)  It  is  found  in  the  cruciferous  plants,  cabbage,  mustard,  &LC.  ; 
in  the  fungous  tribe,  mushrooms,  &c.  and  in  all  plants  that  putrefy 
with  an  animal  odor. 

(c.)  Its  properties  are  interesting  principally  in  combination;  es- 
pecially in  animal  matter ;  in  the  nitric  compounds  ;  in  ammonia^ 
and  with  chlorine  and  iodine  ;  for  an  account  of  which,  see  the  sections 
containing  those  subjects. 

8.  POLARITY. — It  resorts  to  the  negative  pole  in  the  electro-gal- 
vanic circuit,  and  is  therefore  considered  as  electro-positive. 

9.  Its  combining  weight  is  14,  hydrogen  being  1. 

Nitrogen  is  possessed  rather  of  negative  than  of  positive  proper- 
ties, but  in  combination,  it  produces  bodies  of  a  highly  active  and  in- 


*  Thomson's  Annals,  II,  284. 

t  When  ammonia,  an  alkali  which  contains  nitrogen,  (or  either  of  its  salts,)  is  gal- 
vanized with  mercury,  it  converts  that  metal  into  an  amalgam,  which  creates  a  sus- 
picion that  its  base  is  metallic ;  but  Gay  Lussac  and  Thenard  say,  that  this  amalgam 
is  immediately  resolved  into  mercury,  ammonia,  and  hydrogen,  even  when  water 
is  not  present,  and  that,  therefore,  it  is  composed  of  these  three  substances  directly 
united  ;  but,  there  may  be  metallic  matter  in  both  ammonia  and  hydrogen,  or  in  hy- 
drogen alone,  because  it  is  contained  in  ammonia,  and  it  is  possible  that  even  ni- 
trogen may  be  an  oxide  of  hydrogen. 


NITROGEN.  195 

teresting  character ;  some  of  the  most  powerful  fulminating  com- 
pounds contain  it.* 

THE  ATMOSPHERE. 

PHYSICAL  PROPERTIES. 

(a.)  Transparent,  colorless,  inodorous,  only  slightly  absorbed  by 
water;  a  bad  conductor  of  heat  and  of  electricity ;  the  latter  when  ac- 
cumulated, passes  through  the  air  in  a  spark,  but  is  diffused  through 
a  vacuum  in  the  form  of  a  luminous  cloud. 

(b.)  The  azure  color  and  other  hues  in  the  atmosphere,  are  pro- 
duced by  reflected  light. 

(c.)  As  we  ascend,  the  sky  grows  darker,  and  at  a  great  height, 
the  stars  with  the  lustre  of  silver,  are  contrasted  with  a  basis  of  black. 

(d.)  Specific  weight,  1.;  it  is  unity  for  all  other  aeriform  fluids  ; 
100  cubic  inches,  at  the  medium  temperature  and  pressure,  weigh 
30.50  grains. f  Compared  with  water,  it  is  ji^  of  the  weight  of 
that  fluid.  Gallileo  ascertained  in  1640,  that  it  has  weight,  and  Tor- 
ricelli  introduced  the  barometer  tube  in  1643. 

(e.)  Absolute  weight ;  at  the  ocean  level,  about  fifteen  pounds  on 
the  square  inch,  equal  to  thirty  four  feet  of  water,  and  thirty  inches  of 
mercury. — Henry. 

(f.)  Jls  we  ascend,  the  heights  being  in  an  arithmetical  ratio,  the 
weight  decreases  in  a  geometrical  ratio  ;  at  three  miles  elevation,  it 
sustains  15  inches  of  mercury;  at  six  miles,  7.5  inches;  at  nine 
miles,  3f  inches ;  at  fifteen  miles,  about  1  inch. — Id. 

Air  is  compressed  in  direct  proportion  to  the  force  applied.  Dou- 
ble the  force  will  reduce  it  to  half  the  volume ;  double  the  force 
again,  and  its  volume  will  be  again  reduced  one  half,  that  is,  to  one 
quarter  of  its  first  volume,  and  so  on.  A  force  has  been  applied  to 
it,  equal  to  110  atmospheres,  and  the  law  stated  above,  was  found 
still  to  hold  good.J 


*  In  the  Eng.  Jour,  of  Science,  Vol.  XIX.  17,  Mr.  Faraday  has  given  an  ac- 
count of  an  ingenious  method  of  detecting  minute  portions  of  nitrogen,  by  the  for- 
mation of  ammonia.  D  is  a  glass  tube,  four  or  five  inches  long,  and  one 
fourth  of  an  inch  in  the  bore.  At  a,  there  is  some  zinc  foil ;  at  b,  a 
piece  of  potash ;  at  c,  a  piece  of  turmeric  paper  moistened  with  pure  wa- 
£  ter,  at  the  lower  end,  which  is  two  inches  above  the  potash ;  heat  the 
ft  lower  end  of  the  tube  only  in  the  spirit  lamp  so  a?  to  melt  the  potash,  and 
almost  instantly,  the  moistened  paper  will  be  reddened,  indicating  an  al- 
kali, and  it  is  evident  that  it  is  ammonia,  because  the  color  is  discharged 
when  the  paper  is  withdrawn,  and  the  colored  part  laid  on  the  warm  tube. 

Sea  sand  handled  after  ignition,  yields  ammonia,  which  is  discovered  by  this  treat- 
ment.— Ib. 

t  Shuckburgh  30.199.— Brande, 
t  Ed.  Jour.  Science,  No.  VIII,  224, 


196  NITROGEN. 

Mr.  Perkins  states,  that  he  has  applied  to  it  a  pressure  of  2000 
atmospheres,  and  he  supposed  that  he  had  thus  compressed  it  into  a 
liquid,  but  as  this  liquid  was  permanent  under  the  common  pressure, 
it  is  probable  it  was  water  only.  As  we  descend  below  the  surface  of 
the  earth,  the  density  and  pressure  of  the  air  continue  to  increase 
in  the  same  ratio.  "  In  very  deep  mines,  water  will  not  boil  till  heat- 
ed 3  or  4  degrees  above  212°*. — Murray. 

(g.)  The  greater  part  of  the  atmosphere  is  within  three  or  four 
miles  of  the  earth's  surface. 

(h.)  The  phenomena  of  refraction  indicate  that  the  atmosphere  is 
at  least  forty  or  forty  five  miles  high. 

(i.)  Dr.  Wollaston  thinks  that  the  atmosphere  has  limits  fixed  by 
gravity,  counteracting  the  elasticity  imparted  by  caloric,  (Phil.  Trans. 
1822,f)  and  on  account  of  the  absence  of  refraction,  (the  heavenly 
bodies  not  being  disturbed  in  their  apparent  position,)  it  is  asserted 
that  neither  the  sun  nor  Jupiter  has  any  atmosphere  ;  hence  the 
earth's  atmosphere  is  not  indefinitely  divisible,  and  does  not  extend 
to  those  bodies,  and  therefore  it  is  thought  that  its  ultimate  atoms 
must  be  indivisible,  and  this  is  regarded  as  a  direct  proof  of  the  truth 
of  the  atomic  theory,  or,  in  other  words,  of  the  existence  of  indivisi- 
ble atoms  or  particles. 

(/.)  WINDS  are  produced  by  the  ascent  of  rarefied  air  arising  from 
the  pressure  of  colder  and  heavier  air  towards  the  heated  place. 
Thus,  as  already  stated,  page  68,  are  produced  the  trade  winds, 
monsoons,  and  land  and  sea  breezes,  and  the  irregular  winds. 

(k.)  The  draught  of  a  chimney  is  owing  to  atmospheric  pressure; 
the  column  of  air  in  the  chimney  rarefied  by  heat,  is  lighter  than  the 
adjacent  column  of  colder  air,  and  therefore  ascends  from  the  pre- 
ponderance of  the  latter. 

(I.)  The  refractive  power  of  the  air  is  observed  in  the  elevation 
of  ships  and  other  objects  near  the  horizon,  and  in  the  effect  on  the 
heavenly  bodies  in  the  same  situation,  causing  them  to  emerge  sooner 
when  rising,  and  to  linger  later  when  setting. 

(m.)  It  has  been  already  stated  that  the  higher  regions  of  the  at- 
mosphere are  cold  ;  the  temperature  in  the  lower  regions,  dimin- 
ishes at  the  rate  of  one  degree  for  every  three  hundred  feet. 

2.  CHEMICAL  PROPERTIES. 

(a.}  Air  supports  combustion,  as  every  one  knows. 
b.)  It  generates  acidity  in  vinous  fluids. 

(c.)  It  oxidizes  some  of  the  metals,  at  the  common  temperature, 
and  most  of  them  at  ignition. 

*  It  is  calculated,  that  at  46  miles  below  the  surface,  air  would  have  the  density 
of  quicksilver. 

t  For  an  excellent  analysis  of  this  curious  paper,  see  Murray,  6th  Edit.  Vol.  I, 
p.  413. 


NITROGEN.  197 

(d.)  Very  great  rarefaction  diminishes,  and  even  destroys  its  pow- 
er of  supporting  combustion. 

(e.)  Great  condensation  does  not  increase  the  intensity  of  the  com- 
bustion, although  it  is  sustained  for  a  longer  time. 

(f.)  Mixture  with  various  gases  diminishes  it.* 

3.  COMPOSITION,   IN  VOLUME,  80   NITROGEN,  20    OXYGEN — BY 
WEIGHT,  oxygen  22.22 

nitrogen     -  -  77.77 

100.00  very  nearly. f 

This  proportion  of  oxygen  is  undoubtedly  that  which  is  best  adapt- 
ed to  the  support  and  comfort  of  human  life,  and  to  the  convenience 
of  all  the  animal  creation.  Experiments  have  proved  that  animals 
compelled  to  breathe  oxygen  gas  alone,  soon  become  feverish  from 
excess  of  stimulus,  and  life  is  eventually  destroyed  by  the  intense- 
ness  of  its  own  functions  ;  just  "  as  a  candle  burns  brighter  in  oxygen 
gas,  and  is  more  quickly  consumed,  so  in  this  gas,  the  flame  of  life 
would  be  more  vivid,  but  sooner  burnt  out." 

Most  chemists  have  stated  the  composition  of  air  at  21  per  cent,  of 
oxygen.  Dr.  Henry  states  that  he  could  never  satisfy  himself  wheth- 
er it  was  20  or  21  ;  Dr.  Hare  obtained  very  constantly  20.66,  but 
20  corresponds  with  the  theory  of  volumes,  viz.  1  to  4,  and  also  of 
definite  proportions  by  weight,  that  is,  1  proportion  of  oxygen  8,  to 
2  of  nitrogen  28.  Still  the  greater  number  of  chemists  do  not  admit 
that  the  atmosphere  is  a  chemical  compound. 

4.  MEANS  OF  ANALYSIS. 

They  are  numerous  ;  every  substance  which  abstracts  oxygen  with- 
out returning  any  thing  ^  may  be  employed  for  this  purpose. 

(a.)  Phosphorus  is  effectual,  either  by  slow  or  rapid  combustion ; 
the  latter  is  the  most  convenient  process,  and  if  we  subtract  T\f  of 
the  volume  on  account  of  the  vapor  of  phosphorus  dissolved,  in  the 
nitrogen,  the  result  will  be  accurate. 

(b.)  Iron  filings  and  sulphur  moistened,  and  standing  in  contact 
with  a  confined  portion  of  air  remove  the  oxygen.^ 

(c.)  Quicksilver  heated  in  the  confined  air  of  a  retort,  forms 
oxide  of  mercury. 

(d.)  Many  other  things  to  be  mentioned  in  their  place,  produce  a 
similar  effect ;  see  hydrogen,  nitric  oxide  gas,  hydro-sulphurets,  &c. 

In  all  these  cases,  oxygen  is  abstracted  and  nitrogen  gas  is  left,  and 
we  know  of  nothing  which  will  remove  the  latter  gas,  and  leave  the 


*  See  Henry,  10th  Lon.  Ed.  Vol.  I,  p.  296. 

t  Thomson's  Principles  of  Chemistry,  Vol.  I,  p.  100.  t  Turner. 

§  If  they  stand  too  long,  hydrogen  may  be  evolved  from  the  decomposition  of 
water. 


198  NITROGEN. 

oxygen.     The  process  of  analysis  of  the  air  is  called  eudiometry, 
the  instrument,  an  eudiometer.* 

5.  CONDITION  OF  THE  ELEMENTS  OF  THE  ATMOSPHERE. 
(a.)  It  has  been  already  stated,  that  most  chemists  suppose  the  at- 
mosphere to  be  a  mixture  of  the  two  gases. — In  favor  of  this  view,  it 
may  be  said  that  there  is  not,  as  in  most  cases  of  chemical  combi- 
nation, any  change  in  volume ;  4  volumes  of  nitrogen  and  1  of  oxy- 
gen, forming  precisely  5  volumes  of  the  mixture  ;  the  refractive  pow- 
er and  the  agency  in  combustion  and  respiration,  is  just  what  would 
arise  from  the  operation  of  the  mixed  gases,  and  even  water,  in  a  de- 
gree, separates  them,  because  ebullition  expels  from  rain  water  more 
than  28  per  cent,  of  oxygen  ; j-  the  extended  surface  of  the  drops  of 
rain  being  peculiarly  favorable  to  the  efficiency  of  a  weak  affinity ; 
also,  a  small  quantity  of  air  agitated  with  a  large  quantity  of  water, 
has  all  its  oxygen  absorbed,  and  but  little  of  its  nitrogen.  On  the 
other  hand,  as  the  proportions,  both  by  volume  and  weight,  corres- 
pond with  the  theory  of  definite  proportions ;  as  there  is  no  inequality 
in  the  mixture  arising  from  the  difference  in  specific  gravity,  the  at- 
mosphere being  every  where  the  same  ;{  even  if  the  gases  are  not  com- 
bined, the  winds  would  tend  greatly  to  preserve,  in  equable  mixture, 
aeriform  fluids  whose  gravity  is  so  nearly  equal. 

(b.)  Perhaps  it  is,  rather,  a  feeble  combination. — Analogous  to  the 
many  which  exist  between  palpable  substances  where  the  properties 
are  not  altered.  (See  p.  159.)  There  is  no  improbability  that  gases 
may  be  united  by  a  very  feeble  affinity,  and  a  strong  one  would,  in 
this  case,  be  incompatible  with  the  exigencies  of  animal  and  vegeta- 
ble life,  and  with  the  demands  of  combustion.  It  is  indispensable 
that  the  atmosphere  yield  up  its  elements  readily. 

6.    Constancy  of  the  proportions. 

(a.)  They  never  vary,  except  from  the  operation  of  limited  local 
causes,  such  as  combustion  and  respiration.  The  air  which  Gay 
Lussac  brought  down  from  21.735  feet  above  the  earth,§  contained 

*  The  term  alludes  to  the  health  of  the  atmosphere,  as  it  was  supposed  to  be  af- 
fected by  the  proportion  of  oxygen  ;  the  Greek  particle  £i>,  signifying  well,  and  Atoj, 
the  atmosphere,  derived  from  Jupiter,  which  in  Greek  is  Zev$,  Gen.  Awj,  used  for 
the  atmosphere,  t  Edin.  Jour.  No.  8,  p.  211,  quoted  by  Dr.  Turner. 

t  Mr.  Dalton's  views  of  the  constitution  of  the  atmosphere  and  of  mixed  gases,  are 
opposed  to  this  opinion.  See  Henry,  Vol.  I,  p.  299,  10th  Lon.  Ed.  In  a  vertical 
tube,  or  in  two  vials  thus  connected  by  a  tube,  hydrogen  gas  will  in  a  few  hours  de- 
scend, and  carbonic  acid  gas  ascend,  so  as  to  mix  with  each  other  contrary  to 
gravity.  Still,  in  chemical  experiments,  we  find  it  important  to  favor  the  mixing  of 
gases  of  remarkably  different  specific  gravity,  by  adding  the  lightest,  last;  otherwise 
the  mixture  will  be  imperfect  and  tardy.  The  great  mobility  of  gases,  and  the  waves 
and  currents  so  easily  produced  in  them  by  even  slight  variations  of  temperature, 
might  be  expected  to  favor  their  mixture  in  the  course  of  time. 

§  At  that  height,  an  exhausted  bottle  was  opened,  filled  with  air,  and  then  closed  ; 
after  his  descent,  it  was  opened  under  water,  which  rushed  in  and  filled  half  of  it, 
thus  proving  the  great  rarity  of  the  air. 


NITROGEN.  199 

the  regular  proportion  of  oxygen  5  so  does  that  obtained  in  the  deepest 
mines  ;  that  transported  from  Egypt  and  the  African  sands,  and  from 
Mont  Blanc  and  Chimborazo,  had  the  same  constitution.* 

(b.)  This  constancy,  as  has  been  generally  supposed,  is  maintained 
by  the  agency  of  the  vegetable  kingdom. — See  carbonic  acid  and  veg- 
etables. Living  vegetables  in  the  sun's  light,  give  out  oxygen  gas 
and  decompose  carbonic  acid  for  food ;  in  the  night,  they  absorb 
oxygen  and  give  out  carbonic  acid,  but  Priestley  and  Davy  say, 
that  they  give  out  more  oxygen  than  they  consume,  and  therefore 
they  purify  the  air. 

(c.)  According  to  Prevost,  100  years  would  consume  only  T^Votn 
part  of  the  weight  of  the  oxygen  in  the  atmosphere,  making  due  allow- 
ance for  all  the  consuming  processes  that  are  going  on,  and  therefore 
if  they  had  gone  on  even  at  the  same  rate  from  the  creation  of  man, 
the  consumption  would  have  been  but  the  T^¥  part,  and  doubtless  it 
has  not  been  half  of  that,  that  is,  o-j-^.  Some  have  supposed,  that 
volcanic  fires  expel  oxygen  from  various  mineral  bodies ;  some,  that 
nitrogen  is  absorbed  into  the  bodies  of  animals,  and  others,  that  hy- 
drogen is  obtained  by  plants  from  the  decomposition  of  water  ;  all  of 
which  processes  would  either  throw  oxygen  into  the  air,  or  tend  to  give 
it  a  preponderance,  but  none  of  these  suggestions  are  proved  to  be  true. 

7.  AGENCY  IN  RESPIRATION. 

(«.)  Animal  life  universally,  in  all  its  forms,  is  sustained  by  the 
oxygen  of  the  air. 

(6.)  The  nitrogen  appears  to  be  merely  a  diluent,^  and  not  to  act 
except  under  certain  peculiar' circumstances,  but  it  is  not  improbable 
that  it  answers  some  positive  purpose  in  the  animal  economy,  whose 
nature  is  not  yet  understood. 

(c.)  The  principal  effect  in  respiration,  appears  to  be  the  abstrac- 
tion of  carbon  from  the  blood. — See  carbonic  acid  and  respiration. 

7.  THERE  ARE  OTHER  BODIES  IN  THE  ATMOSPHERE. 

(a.)  Perhaps  the  only  ones  that  are  constant,  are  carbonic  acid, 
about  ToW  or  sVu «»  an^  it  never  exceeds  yj^  and  aqueous  vapor; 
T^ot  by  weight.  Saussure  found  carbonic  acid  at  the  top  of  Mont 
Blanc,  and  it  exists  at  every  height  hitherto  attained,  but  the  aque- 
ous vapor  varies  with  the  temperature;  air  at  60°  may  contain  10 
grains  of  water  to  a  cubic  foot,  and  4.5  at  43°,  and  the  quantity  in- 
creases in  a  high  ratio  as  the  temperature  is  raised.  On  high  mountains, 

*  Mr.  Faraday's  analysis  of  air  from  the  Arctic  regions,  shows  a  decided  and  con- 
stant difference  between  it  and  the  air  of  London,  of  at  least  1.374  per  cent.  See 
Appendix  to  Parry's  3d  voyage,  Lond.  Ed.  p.  240.  No  explanation  is  given  to  ac- 
count for  the  cause  of  this  difference,  but  !  have  little  doubt  that  it  is  owing  to  the 
deficiency  of  vegetation  in  high  northern  latitudes. — (Communicated.)  J.  T. 

t  \Ve  cannot  be  positive  on  this  point ;  it  is  certainly  possible  that  it  has  some  more 
important  agency. 

t  Mr.  Dalton  found  it  rather  more  than  this  in  the  air  which  an  assembly  of  two 
hundred  people  had  breathed  for  more  than  two  hours. 


200  NITROGEN. 


it  is  very  small ;  caustic  potash  remained  dry  on  the  peak  of  Ten- 
erifFe,  at  12,176  feet  above  the  sea. 

(b.)   These  adventitious  things  probably  vary  in  their  proportion. 

(c.)   Besides  these,  there  are  other  bodies. 

Various  inflammable  gases,  from  marshes  and  stagnant  waters, 
from  putrefaction,  &c. 

Jlmmonia,  from  the  latter  cause,  and  from  some  plants. 

Vapors  and  effluvia,  from  every  volatile  thing,  from  fluids,  flowers, 
&c.producmg  odors  and  aroma. 

The  matter  of  contagion. — It  is  too  subtile  as  yet  for  our  processes, 
doubtless  it  is  something  aerial,  more  subtile  than  any  gas  yet  known. 
It  is  combated  successfully  by  chlorine,  and  to  a  degree,  by  acid  gases. 

"  Seguin  examined  the  infectious  air  of  a  hospital,  the  odor  of 
which  was  almost  intolerable,  and  could  discover  no  appreciable  de- 
ficiency of  oxygen,  or  other  peculiarity  of  composition." — Turner. 

Upon  the  usual  estimation  of  21  per  cent,  of  oxygen  in  the  air,  its 
contents  will  be,  including  only  those  bodies  whose  existence  has 
been  proved  to  be  constant. 

Nitrogen  gas,  77.5  by  measure,       75.55  by  weight. 

Oxygen  gas,  21.  "  23.32         " 

Aqueous  vapor,  1.42         "  1.03 

Carbonic  acid  gas,  .08         "  .10*       " 

Dr.  Prout  discovered  that  the  specific  gravity  of  any  gas  is  ob- 
tained by  multiplying  its  combining  weight  by  .555,  which  is  half  the 
sp.  gr.  of  oxygen  gas,  air  being  1.  or  10. ;  half  the  sp.  gr.  of  oxygen 
is  taken  because  half  a  volume  of  oxygen  represents  its  combining 
power.  The  above  rule  applies  to  gases  whose  equivalents  are  es- 
timated with  reference  to  oxygen  as  unity ;  if  hydrogen  be  unity, 
then  multiply  the  equivalent  by  that  scale,  by  .555  as  before,  and  di- 
vide the  product  by  8,  which  is  the  combining  weight  of  oxygen  upon 
that  scale.  Or  the  same  result  will  be  obtained  by  multiplying  the 
equivalent  upon  the  hydrogen  scale,  by  the  number  expressing  the 
sp.  gr.  of  hydrogen,  namely,  0.0694. — Id. 

Remarks. 

If  we  could  suppose  our  atmosphere  to  be  removed,  (the  laws  of 
heat  and  of  pressure  remaining  as  they  now  are,)  another  atmosphere 
would  be  immediately  formed,  consisting  of  aqueous  vapor,  and  of 
every  thing  else  that  could,  at  the  given  temperature,  assume  the  ae- 
riform condition  5  this  process  would  go  on  until  the  pressure  react- 
ed with  sufficient  power  to  become  mechanically  a  substitute  for  the 
present  atmosphere.  With  similar  physical  laws,  we  cannot  there- 
fore understand,  how  any  of  the  heavenly  bodies  can  be  without  at- 
mospheres, of  some  kind  or  other. 

*  Murray,  I,  433. 


HYDROGEN,  201 


SEC.    III. HYDROGEN WATER HAREMS  BLOWPIPE. 

HYDROGEN. 

The  name  is  derived  from  u^wp  and  ysvvaw,  or  ysivofwu,  signifying 
the  generator  of  water  ;  the  popular  name  is  inflammable  air ;  the 
miners  call  it  wild  fire. 

1.  DISCOVERY. 

It  was  probably  known  to  the  ancients,  but  Mr.  Cavendish,  A.  D. 
1766,  first  proved  it  to  be  a  distinct  gas,*  as  Dr.  Black  had  done 
nine  years  earlier  with  respect  to  carbonic  acid  gas,  which  was  the 
first  aeriform  body,  other  than  common  air,  whose  existence  was 
established,  and  hydrogen  was  the  second. f 

2.  PROCESS. 

It  is  always  obtained,  directly  or  indirectly,  from  the  decomposi- 
tion of  water. 

(a.)  Fragments  of  zinc,  or  iron  filings,  or  turnings,  1  part,  sul- 
phuric acid  2  parts,  water  5  or  6  parts ;  add  the  water  to  the  metal ; 
then  the  acid  by  separate  portions,  with  intermediate  agitation,  the 
vessel  being  held  under  a  chimney,  till  the  effervescence  comes  on, 
when  the  gas  must  be  received  over  water,  in  inverted  vessels  filled 
with  that  fluid.  A  glass  retort,  or  a  glass  flask,  furnished  with  a  bent 
tube  is  all  the  apparatus  that  we  need.  A  vessel  of  lead,  or  even  of 
plate  tin,  will  answer  very  well,  but  its  opacity  is  an  inconvenience. 
Muriatic  answers  nearly  as  well  as  sulphuric  in  obtaining  this  gas,  but 
the  latter  is  much  cheaper. 

(6.)  It  is  obtained  still  purer,  by  the  decomposition  of  water,  by 
iron ;  see  water. 

(c.)  A  purer  gas. — Hydrogen  gas  as  obtained  by  the  above  pro- 
cesses, is  not  quite  pure ;  if  washed  with  a  little  lime  water,  or  caustic 
potash,  it  is  deprived  of  carbonic  acid,  and  of  sulphuretted  hydrogen, 
which  sometimes  arises  from  sulphur  in  the  zinc,  and  by  being 
passed  through  alcohol,  it  loses  its  odor,  which  is  probably  owing  to 
a  volatile  oil,{  supposed  to  be  generated  between  the  carbon  in  the 
metal  and  the  hydrogen.  A  little  carburetted  hydrogen  is  very  apt 
to  remain ;  and  to  have  the  gas  absolutely  pure,  the  zinc  must  be  pre- 


*  Phil.  Trans,  v.  66.  p.  144. 

t  Carbonic  acid  gas  was  discovered  in  1756  or  7;  hydrogen  in  1766 ;  nitrogen 
in  1772 ;  oxygen  and  chlorine  in  1774.  These  important  discoveries  laid  the  found- 
ation of  the  pneumatic  chemistry. 

t  Which,  on  diluting  the  alcohol,  makes  its  appearance,  after  a  few  days,  upon 
the  surface  of  the  water.  Other  authors  suggest  that  arsenical  particles  derived 
from  the  zinc,  cause  the  smell. 

26 


202  HYDROGEN. 

viously  distilled.     It  sometimes  has  a  little  zinc  or  iron  suspended 
or  dissolved  in  it. 

3.  THEORY  OF  THE  PROCESS. 

The  acid  is  not  altered,  but  the  water  is  decomposed  ;  its  oxygen 
passing  to  the  iron,  converts  it  into  an  oxide,  and  its  hydrogen  is 
evolved ;  the  acid  unites  with  the  oxide  of  iron,  and  forms  sulphate 
of  iron,  which  appears  in  green  crystals,  as  soon  as  the  mixture  is 
cold.  How  the  acid  operates  to  favor  the  decomposition  is  not  al- 
together clear.  * 

4.  PHYSICAL  PROPERTIES. 

(a.)  It  is  colorless  and  transparent.  As  commonly  obtained,  it 
has  a  smell  slightly  fetid.  If  obtained  over  mercury,  the  odor  is 
much  diminished.  It  is  scarcely  absorbed  by  water,  unless  it  has 
been  freed  from  common  air,  when  100  cubic  inches  of  that  fluid 
take  up  1 J  inches  of  the  gas ;  with  strong  pressure  the  water  absorbs 
one  third  of  its  volume. 

(6.)  It  refracts  light  more  powerfully  than  any  gas,  agreeably  to 
the  general  law  with  respect  to  inflammable  bodies;  ratio  6.6 — air 
being  l.f 

(c.)  Specific  gravity  0.694,  air  being  1,  just  16  times  lighter  than 
oxygen ;  weight  2.116  grs.  for  100  cub.  in.  at  the  medium  tempera- 
ture and  pressure. f  One  cubic  inch  weighs  but  little  more  than  j\ 
of  a  grain,  and  fifty  cubic  inches  but  little  more  than  one  grain ; 
it  is  the  lightest  form  of  matter  hitherto  obtained.  "  It  is  about 
200,000  times  lighter  than  mercury,  and  300,000  times  lighter  than 
platina." — Hare. 


*  This  used  to  be  called  a  case  of  disposing  affinity  ;  the  acid  being  disposed  to 
unite  with  the  oxide  of  iron  about  to  be  formed,  by  the  transfer  of  the  oxygen  of  the 
water  to  the  iron  ;  this  explanation  appears  to  be  no  more  than  verbal,  as  the  oxide 
of  iron  cannot  exert  an  attraction  before  it  is  in  existence  ;  but  if,  as  suggested  by 
Murray,  the  acid  be  supposed  to  exert,  simultaneously,  an  attraction,  both  for  the 
oxygen  of  the  water,  and  for  the  iron,  it  may  thus  aid  the  combination  of  the  former 
with  the  latter,  and  then  the  acid  will  combine  with  the  oxide  of  iron.  But  there 
is  no  evidence,  except  that  which  is  afforded  by  the  fact  in  question,  that  such  an 
attraction  exists  between  the  acid  and  the  oxygen,  and  the  acid  and  the  iron.  It  ap- 
pears to  me  better  to  say  that  we  do  not  understand  it,  and  to  wait  till  we  do,  be- 
fore we  attempt  to  explain  the  fact.  The  heat  generated  by  the  action  of  the  acid 
and  water,  will  not  explain  the  decomposition,  for  the  cold  diluted  acid  will  rapidly 
evolve  hydrogen  gas  from  iron;  it  grows  hot,  it  is  true,  during  the  action,  but  the 
heat  is  not  the  cause,  it  is  the  effect  of  the  action.  There  is  another  theoretical  diffi- 
culty in  this  experiment.  The  rapid  evolution  of  gas,  and  especially  of  one  whose 
capacity  for  heat  exceeds  that  of  all  known  bodies,  ought  not,  upon  the  received 
theory  of  heat,  to  evolve  that  power;  the  mixture  ought  to  grow  cold.  Again,  the 
crystallization  of  the  sulphate  of  iron  is  rapid,  and  begins  even  before  the  mixture 
is  cold,  and  proceeds  the  more  rapidly  the  colder  the  liquor  grows;  but  the  evolu- 
tion of  a  solid  from  fluids  ought  to  produce  heat. 

I  Henry,  vol.  l.p.  154.  I  Thomson. 


HYDROGEN. 


203 


(d.)  Balloons*  are  filled  with  it.  The  principle  of  balloons  is  very- 
well  exhibited  by  filling  soap  bubbles  with  hydrogen  gas,  or,  better  still, 
with  the  explosive  mixture  of  oxygen  and  hydrogen  ;  they  will  rise  in 
the  atmosphere  ;  the  former  rapidly,  the  latter  more  quietly,  and  the 
flame  of  a  candle  will  fire  them  as  they  pass ;  in  the  latter  case  there  is 
a  considerable  explosion.  The  solution  of  soap  should  be  strong,  and 
used  cold,  and  a  metallic  pipe  will  allow  the  bubbles  to  be  more  easily 
disengaged  than  one  of  clay.  If  a  dish  of  strong  soap  water  be  blown 
up  full  of  bubbles  of  the  mixed  gases,  it  detonates  powerfully,  when  fir- 
ed by  throwing  a  burning  match  into  it.  A  bladder,  filled  in  the  same 
manner,  may  be  fired  by  piercing  it  with  a  sharp  wire,  fixed  to  a  pole, 
and  having,  appended  to  the  wire,  a  burning  rag  moistened  with  spirit 
of  turpentine. 

(e.)  Musical  tonesf  are  produced  when  a  small  jet  of  this  gas  is 
burned  in  a  glass  or  other  tube.  They  are  produced  also  by  car- 
bonic oxide,  coal  gas,  olefiant  gas,  and  vapor  of  ether,  burning  in  a 
jet ;  the  sounds  are  produced  in  bottles,  flasks,  and  vials ;  and  globes, 
from  seven  to  two  inches  in  diameter,  give  very  low  tones.  The  re- 
port is  considered  by  Mr.  Faraday,  agreeably  to  the  views  of  Sir 
H.  Davy,  as  only  a  continued  explosion.  J 

5.  CHEMICAL  PROPERTIES. 

(a.)  Hydrogen  possesses  extensive  powers  of  com- 
bination, as  will  be  seen  in  the  history  of  other  bo- 
dies, especially  of  chlorine,  iodine,  sulphur,  carbon, 
&c.,  and  of  animal  and  vegetable  substances. 

(6.)  ITS  INFLAMMABILITY  IS  ITS  MOST  IMPORT- 
ANT PROPERTY. 

(c.)  A  candle  kindles  a  jar  of  it,  but  is  itself  ex- 
tinguished by  immersion  in  the  gas,  and  is  relighted 
if  the  wick  again  touch  the  flame ;  see  the  an- 
nexed figure  of  Dr.  Hare,  which  needs  no  explana- 
tion. 


*  For  some  curious  and  amusing  speculations  respecting  the  possible  uses  of  bal- 
loons, see  the  Am.  Jour.  Vol.  XI,  XII  and  XIII.  Gay  Lussac,  who  ascended  till  the 
mercury  in  the  barometers  stood  at  11  inches,  ascertained,  that  magnetism  and  elec- 
tricity existed  at  that  height,  in  undiminished  energy,  and  that  the  proportion  of 
oxygen  and  nitrogen,  was  the  same  as  at  the  surface  of  the  earth. 

t  A.  jet  of  flame  from  one  of  the  gazometers,  p.  184,  is  admirably  adapted  to  insure 
the  success  of  this  pleasing  experiment.  By  turning  the  key,  the  jet  is  accurately 
regulated,  and  a  great  variety  of  tones,  from  the  most  acute  to  the  most  grave,  is 
easily  produced  by  using  tubes  of  different  materials,  diameters,  length  and  thick- 
ness; hardly  any  "tube  comes  amiss,  and  the  same  tube  will  give  a  variety  of  tones, 
if  moved  up  and  down,  while  the  flame  is  in  it. 

t  Eng.  Jour,  of  Science,  No.  10. 


204 


HYDROGEN. 


It  is  plain  from  this  experiment,  that 
hydrogen  gas  is  a  combustible,  but  not  a 
supporter  of  combustion  ;  it  burns  where 
it  is  in  contact  with  the  air,  but  will  not 
permit  a  candle  to  burn  in  it ;  on  the 
contrary,  oxygen  gas  causes  the  candle 
to  burn  more  rapidly,  but,  when  it  is 
withdrawn,  the  gas  does  not  itself  burn. 

(d.)  Hydrogen  gas  burns  in  jets  and 
in  many  pleasing  forms,  as  is  illustra- 
ted by  the  following  figure. 

The  bottle  contains  the  materials  to 
afford  the  gas,  which  is  kindled  at  the 
orifice  of  the  tube,  (the  common  air 
having  been  allowed  previously  to  es- 
cape,) and  the  jet  is  called  the  philo- 
sophic candle.  The  flame  is  very  pale, 
but  Dr.  Hare,  whose  cut  is  annexed, 
ascertained,  that  the  addition  of  one 
seventh  of  spirit  of  turpentine  to  the 
materials,  would  "  obviate  this  defect." 

(e.)  If  mingled  with  common  air,  5  or  6  volumes,  and  hydrogen 
gas  2,  it  explodes  on  contact  with  the  flame  of  a  candle. 

(/.)  More  violently  with  oxygen  gas  1  part,  and  hydrogen  2,  by 
volume.  This  mixture  should  not  be  exploded  in  glass  vessels,  un- 
less in  small  quantities,  and  unless  the  glass  is  strong,  and  well  an- 
nealed. It  is  better  to  use  tubes  of  tin  plate,  or  sheet  copper  ;  a 
cylinder  of  the  latter,  closed  at  one  end  ;*  or  two  cones  joined  at  the 
base,  and  furnished  with  a  mouth  that  can  be  corked  firmly,  and  with 
a  touch  hole,  make  a  good  discharging  pistol.  It  is  first  filled  with 
water ;  then  with  the  mixed  gases,  and  then  kindled  by  a  burning 
candle,  or  sulphur  match,  applied  at  the  touch  hole.f  Hydrogen  gas 
burns  in  volume  with  a  yellowish  flame,  sometimes  with  points  and 
sparks  of  red. 

(g.)  Hydrogen  gas,  from  its  levity,,  escapes  rapidly  from  vessels 
held  with  their  mouths  upward ;  but  it  remains  a  good  while  in  con- 
tact with  the  air,  without  escaping,  if  their  mouths  are  in  the  reverse 


*  If  this  mixture  be  allowed  to  escape  from  beneath  water,  the  bubbles  explode 
violently  on  touching  a  flame  at  the  surface  ;  a  glass  vessel  should  never  be  used  in 
this  experiment. 

t  If  the  double  cone  be  filled  with  hydrogen  and  held  with  the  mouth  downward, 
leaving  the  touch  hole  at  the  top  open,  the  gas  will  slowly  escape  and  may  be  kin- 
dled, being  gently  pressed  upwards  by  the  atmosphere.  If  when  partly  burned,  the 
instrument  be  turned  upwards,  the  mixed  gases  will  explode. — J.  G. 


HYDROGEN.  205 

position.  It  may  be  turned  upward  into  a  vessel  full  of  air,  and  will 
expel  it,  and  take  its  place. 

(A.)  Suspend,  out  of  the  water  of  the  pneumatic  cistern,  a  tall  nar- 
row jar,  full  of  the  gas,  keeping  a  glass  plate  over  its  mouth,  until  it 
is  fixed  in  its  place  :  then  withdraw  the  plate  without  agitation ;  on 
putting  a  burning  candle  to  the  mouth,  a  quarter  of  an  hour  after, 
the  gas  will  take  fire  with  the  usual  slight  explosion,  and  will  then 
continue  to  burn  quietly  away,  thus  proving  that  owing  to  its  levity, 
the  pressure  of  the  atmosphere  had  kept  it  in  its  place. 

(i.)  Reverse  the  experiment,  by  filling  the  same  jar  again  with 
the  same  gas ;  cover  its  mouth  with  the  glass  plate,  and  turn  it  up ; 
let  an  assistant  hold  a  candle  a  foot  above,  and  when  the  plate  is 
withdrawn,  the  gas,  now  rapidly  rising,  will  take  fire  as  it  is  passing 
upward,  and  will  exhibit  a  volume  of  flame  in  the  air  :  the  same 
pressure  which  in  the  former  experiment  kept  it  in  its  place  now 
forces  it  to  rise. 

6.  EFFECTS  ON  ANIMAL  LIFE. 

It  is  hostile  to  life,  but  not  instantly  fatal. 

(a.)  The  lungs  may  be  inflated  with  it  a  few  times  in  succession, 
and  it  may  be  blown  out  without  injury.*  It  produced  in  Mr.  Mau- 
noir  and  Mr.  Paul,  at  Geneva,  a  soft,  shrill,  and  squeaking  voice, 
when  they  attempted  to  speak,  after  breathing  it. 

(b.)  Frogs  placed  in  hydrogen  gas  will  suspend  their  respiration; 
they  have  been  known  to  do  it  for  3J  hours  at  a  time. 

(c.)  In  mixture  with  oxygen,  it  may  be  substituted  for  the  nitro- 
gen, and  a  respirable  atmosphere  might  thus  have  been  made ;  but, 
the  mixture  would  have  been  explosive,  and  the  hydrogen  would 
probably  have  separated  from  the  oxygen  in  consequence  of  its  levity. 

(d.)  It  kills  by  suffocation,  merely  or  principally,  as  water  does. 

(e.)  It  is  not  noxious  to  plants,  and  some,  it  is  said,  even  absorb  it. 

7.  NATURE  OF  HYDROGEN. 

It  is  an  element  in  relation  to  our  knowledge,  and  probably  it  is  a 
real  element.  It  is  a  simple  combustible. 

8.  ITS    IMPORTANCE    AND    DIFFUSION. 

(a.)  It  is  probably,  next  to  oxygen,  the  most  important  element ; 
it  is  exceedingly  abundant,  and  its  compounds  meet  us  almost  every 
where. 

(b.)  It  exists  in  water,  and  all  fluids  used  by  men  and  animals  for 
drink  or  diluents. 


*  Pilatre  de  Rozier  was  accustomed,  not  only  to  fill  his  lungs  with  hydrogen  gas, 
but  to  set  fire  to  it  as  it  issued  from  his  mouth,  where  it  formed  a  very  curious  jet 
of  flame.  He  also  mixed  pure  hydrogen  gas  with  one  ninth  of  common  air,  and  re- 
spired the  mixture  as  usual ;  "  but  when  he  attempted  to  set  it  on  fire,  the  conse- 
quence was  an  explosion  so  dreadful,  that  he  imagined  his  teeth  were  all  blown 
out." 


206 


HYDROGEN. 


(c.)  It  is  a  constituent  of  all  animal  and  vegetable  bodies,  and  is 
found  in  almost  every  part  of  them. 

(d.)  It  exists  in  mineral  coal  of  every  variety,  and  most  abundant- 
ly in  the  bituminous  coal. 

9.  Its  combining  weight,  when  it  is  made  unity  for  other  bodies, 
is  of  course  expressed  by  1  ;  if  oxygen  be  unity,  then  hydrogen  will 
be  .125.     These  are  Dr.  Thomson's  numbers,  but  I  have  already 
stated  the  reasons  why  I  prefer  making  hydrogen  unity,  as  most  wri- 
ters now  do. 

10.  POLARITY. 

Hydrogen,  in  the  galvanic  circuit,  resorts  to  the  negative  pole,  and 
is  therefore  considered  as  electro-positive. 

Self  regulating  reservoirs,  for  hydrogen  and  other  gases,  are 
occasionally  convenient ;  the  following  are  from  Dr.  Hare,  being  im- 
proved upon  the  original  contrivance  of  Gay  Lussac.* 

"Suppose  the  glass  jar 
without,  to  contain  diluted 
sulphuric  acid  ;  the  invert- 
ed bell,  within  the  jar,  to 
contain  some  zinc,  support- 
ed on  a  tray  of  copper,  sus- 
pended by  wires,  of  the 
same  metal,  from  the  neck 
of  the  bell.  The  cock  be- 
ing open,  when  the  bell  is 
lowered  into  the  position  in 
which  it  is  represented,  the 
atmospheric  air  will  escape 
and  the  acid,  entering  the 
cavity  of  the  bell,  will,  by 
aid  of  the  zinc,  cause  hy- 
drogen gas  to  be  copiously 
evolved.  As  soon  as  the 
cock  is  closed,  the  hydro- 
gen expels  the  acid  from  the  cavity  of  the  bell ;  and  consequently, 
its  contact  with  the  zinc  is  prevented,  until  another  portion  of  the 
gas  is  withdrawn.  As  soon  as  this  is  done,  the  acid  re-enters  the 
cavity  of  the  bell,  and  the  evolution  of  hydrogen  is  renewed,  and 
continued,  until  again  arrested,  as  in  the  first  instance,  by  preventing 
the  escape  of  the  gas,  and  consequently  causing  it  to  displace  the 
acid  from  the  interior  of  the  bell,  within  which  the  zinc  is  suspended." 


*  Dr.  Hare  states  that  he  used  an  apparatus  of  this  kind,  at  Williamsburgh,  Va. 
before  he  had  heard  of  that  of  Gay  Lussac.  It  will  be  seen  farther  on,  that  such  a 
contrivance  is  admirably  adapted  for  obtaining  light,  instantaneously,  by  allowing 
the  jet  of  flame  to  flow  upon  spongy  platinum. 


WATER.  207 

Large  self-regulating  reservoir,  for  Hydrogen. 


"  This  figure  represents  a  self- 
regulating  reservoir,  for  hydrogen 
gas;  it  is  constructed  like  that 
described  in  the  preceding  arti- 
cle, excepting  that  it  is  about  50 
times  larger,  and  is  made  of  lead 
instead  of  glass." 

"  This  reservoir  is  attached  to 
the  compound  blowpipe,  in  or- 
der to  furnish  hydrogen ;  and 
may,  of  course,  be  used  in  all 
experiments,  requiring  a  copious 
supply  of  that  gas." 

On  account  of  the  extensive 
uses  of  oxygen  and  hydrogen 
gases,  in  a  philosophical  labora- 
tory, it  is  highly  convenient,  to 
have  them  always  on  hand,  in 
large  quantities ;  and,  of  course, 
in  separate  reservoirs,  between 
which  there  is  no  possibility  of 
communication. 


WATER. SYNTHESIS. 

11.    THE  COMBUSTION  OF  HYDROGEN  PRODUCES  WATER,  and  pTC>- 

vided  the  gases  be  pure,*  it  produces  nothing  else. 

(a.)  Burn  a  jet  of  hydrogen  gas  in  a  tall  glass  tube,  and  water,  in 
visible  drops,  will  soon  line  the  tube. 

(b.)  The  same  may  be  done  in  a  bottle,  filled  either  with  common 
air,  or  with  oxygen  gas. . 

(c.)  Or  burn  a  double  stream  of  the  two  gases,  coming  from 
distinct  reservoirs,  and  mingling  at  the  moment  of  exit. 

In  these  cases  the  receiver  should  be  kept  cold. 

(d.)  If  a  bladder,  furnished  with  a  stop  cock,  and  a  bent  tube,  be 
filled  with  hydrogen  gas,  and  the  gas,  kindled  in  a.  jet,  be  allowed 


*  Sometimes  a  little  nitric  acid  or  nitric  oxide,  is  formed  at  the  expense  of  the  ni- 
trogen; or  carbonic  acid,  from  carburetted  hydrogen,  these  being  accidental  im- 
purities in  the  gases. 


208 


WATER. 


to  burn  under  a  jar  of  common  air,  or  better  of  oxygen  gas, 
standing  over  mercury,  there  will  be  a  rapid  rise  of  the  metal,  and 
water  will  appear,  first  in  vapor,  and  then  in  minute  drops,  lining  the 
interior  of  the  jar. 

(e.)  I  find  it  perfectly  easy  to  fill  a  large  glass  globe  with  oxygen 
gas,  by  allowing  it  to  flow  from  a  reservoir  through  a  tube  descend- 
ing to  the  bottom  of  the  globe,  and  it  is  known  when  the  latter  is  full 
by  applying  a  taper,  blown  out,  and  having  a  little  fire  on  the  wick, 
which  is  then  rekindled  at  the  mouth  of  the  globe.  This  arrangement 
saves  air-pump  exhaustion.  The  hydrogen  gas  is  then  lighted  in  a 
jet,  and  allowed  to  flow  from  a  gasometer  as  long  as  it  is  needed. 
As  I  employ  the  compound  blow-pipe  in  this  experiment,  it  is  easy 
to  let  in  either  oxygen  or  hydrogen  as  it  is  needed,  and  thus  the  com- 
bustion is  continued  at  pleasure.  The  production  of  water  in  this 
mode  is  immediate  and  palpable.  I  subjoin  a  figure  of  a  beautiful  but 
more  complicated  apparatus. 

Lavoisier's  apparatus  for  the  recomposition  of  water. 

"  This  apparatus  con- 
sists of  a  glass  globe, 
with  a  neck  cemented 
into  a  brass  cap,  from 
which  three  tubes  pro- 
ceed, severally  com- 
municating with  an  air 
pump,  and  with  reser- 
voirs of  oxygen  and  hy- 
drogen. It  has  also  an 
isulated  wire,  for  pro- 
ducing the  inflamma- 
tion of  a  jet  of  hydrogen, 
by  means  of  an  electric 
spark.  In  order  to  put 
the  apparatus  into  op- 
eration, the  globe  must 
be  exhausted  of  air,  and 
then  supplied  with  oxy- 
gen to  a  certain  extent. 
In  the  next  place,  hy- 
drogen is  to  be  allowed 
to  enter  it  in  a  jet,  which 
is  to  be  inflamed  by  an 
electric  spark.  As  the 
oxygen  is  consumed, 
more  is  to  be  admitted." 


WATER.  200 

"  I  have  employed  a  wire  ignited  by  galvanism,  to  inflame  the  hy- 
drogen in  this  apparatus,  and  conceive  it  to  be  a  much  less  precari- 
ous method  than  that  of  employing  an  electric  machine,  or  electro- 
phorus."  —  Hare. 

(f.)  Oxygen  and  hydrogen  may  be  combined  by  explosion.  —  This 
happens  of  course,  in  all  cases  where  they  are  fired  together  ;  the 
product  is  lost,  if  the  explosion  finds  vent  into  the  open  air,  but  if 
confined  to  an  eudiometer  tube,  over  mercury,  a  little  water  will  be 
obtained  ;  this  is  never  done  except  for  the  purposes  of  eudiometry, 
which  will  be  mentioned  again. 

(g.)  Oxygen  and  hydrogen  combine  by  pressure.  —  -The  two  gases, 
will  remain  forever  in  mere  mixture,  at  the  common  temperature 
and  pressure,  without  combining  ;  but  by  sudden  and  violent  com- 
pression in  a  syringe,  they  will  explode,  probably  on  account  of  the 
heat  which  is  thus  evolved,  for  "  an  equal  degree  of  condensation, 
slowly  produced,  has  not  the  same  effect." 

These  gases  combine  slowly  above  the  temperature  of  boiling  mer- 
cury, and  below  that  of  glass  when  ignited,  so  as  to  be  just  visible 
in  the  dark. 

12.  PROPORTION  OF  THE  ELEMENTS. 

(a.)  By  volume,  2  hydrogen,  and  1  oxygen, 

by  weight,  88.9  oxygen,     >  , 

«-,     "       11.1  hydrogen,  $  veryi 

The  combining  weight,  if  there  be  one  proportion  of  each, 


Combining  weight  of  water,  9*  or  11.25 

(b.)  The  proportions  of  the  elements  in  water,  have  been  settled 
after  the  most  rigorous  and  often  repeated  analysis.  The  atomic  hy- 
pothesis, and  the  theory  of  definite  and  multiple  proportions,  are  built 
upon  the  result  of  this  analysis.  All  chemists  take  either  oxygen  or 
hydrogen  for  unity,  and  of  late  the  weight  of  opinion  and  authority  is 
evidently  in  favor  of  hydrogen. 

WATER—  ANALYSIS. 

1  .  If  water,  in  the  state  of  steam,  be  passed  over  clean  ignited  iron, 
in  an  iron,  or  in  a  luted  glass  or  earthen  tube,  the  iron  absorbs  the  ox- 
ygen, and  hydrogen  gas  is  obtained  ;  the  weight  of  the  hydrogen 
added  to  the  increased  weight  of  the  iron  equals  that  of  the  water  de- 
composed. Zinc,  antimony,  and  several  other  metals  will  answer  the 
same  purpose  more  or  less  perfectly. 

The  common  arrangement  for  decomposing  water  is  represented 
by  the  following  figure  from  Dr.  Hare. 

*  9  is  the  number  now  generally  adopted. 

27 


210 


WATER, 
Steam  decomposed  by  ignited  iron. 


"  Having  introduced  some  turnings  of  iron  or  refuse  card  teeth, 
into  a  clean  musket-barrel ;  lute  into  one  end  of  the  barrel,  the  beak 
of  a  half  pint  glass  retort,  about  half  full  of  water.  To  the  other 
end  of  the  barrel,  lute  a  flexible  leaden  tube.  Lift  the  cover  off  the 
furnace,  and  place  the  barrel  across  it,  so  that  the  part  containing 
the  iron  turnings,  may  be  exposed  to  the  greatest  heat.  Throw  into 
the  furnace,  a  mixture  of  charcoal,  and  live  coals ;  the  barrel  will 
soon  become  white  hot.  In  the  interim,  by  means  of  a  chauffer  of 
coals,  the  water  being  heated  to  ebullition,  the  steam  is  made  to  pass 
through  the  barrel  in  contact  with  the  heated  iron  turnings." 

"  Under  these  circumstances,  the  oxygen  of  the  water  unites  with 
the  iron,  and  the  hydrogen  escapes  in  the  gaseous  state  through  the 
flexible  tube."  For  1  grain  of  hydrogen  evolved,  the  iron  gains  8  grs. 

2.  Galvanism  with  gold  or  platina  wires,  gives  an  elegant  result; 
the  two  gases,  in  exact  proportion,  being  obtained  in  mixture,  if  the 
two  wires  are  in  the  same  tube  ;  if  in  different  tubes  communicating 
by  a  fluid  or  a  wet  fibrous  solid,  then  the  oxygen  will  be  in  one  tube 
and  the  hydrogen  in  the  other.     If  the  wire  is  oxidable,  hydrogen  gas 
alone  is  obtained  while  the  wire  is  in  the  meantime  oxidized. 

3.  Water  is  readily  decomposed  by  ignited  carbon,  but  the  results 
are  more  complicated  ;  carbonic  acid  gas,  carbonic  oxide,  and  carbu- 
retted  hydrogen  gases  being  obtained. 


WATER.  211 


In  this  account  of  the  composition  of  water,  as  a  matter  of  conven- 
ience, the  synthesis  has  been  given  before  the  analysis,  while  the  re- 
verse order  would  have  seemed  more  natural.  The  synthesis  was, 
however,  first  discovered,  although  in  every  instance  of  obtaining  hy- 
drogen for  the  experiment,  it  must  have  been  preceded  by  an  actual, 
although  unknown  analysis  of  water. 

In  1776,  Macquer  and  De  la  Fond,  at  Paris,  burned  a  jet  of  hy- 
drogen, and  observed  that  drops  of  water  were  condensed  from  it  on 
a  white  China  saucer,  which  was  not  soiled,  and  in  the  following 
year,  a  similar  experiment  was  made  by  Bucquet  and  Lavoisier,  who 
could  not  satisfy  themselves  as  to  what  was  produced,  but  ascertained 
that  it  was  not  carbonic  acid. 

In  the  spring  of  1781,  Mr.  Warltire  and  Dr.  Priestley  fired  the 
mixed  gases,  but  the  water  produced  was  supposed  to  be  accidental, 
or  to  have  been  merely  deposited  from  a  state  of  suspension. 

In  the  summer  of  the  same  year,  and  afterwards,  more  particular- 
ly in  1783,  Mr.  Cavendish  burned  hydrogen  on  a  large  scale,  and 
proved  that  the  product  was  water  ;  an  opinion  which  had  been  be- 
fore entertained  by  Mr.  Watt,  and  communicated  to  Dr.  Priestley 
and  to  De  Luc.  Mr.  Cavendish,  without  any  knowledge  of  Mr. 
Watt's  opinion,  had  drawn  the  same  conclusion,  and  is  therefore  the 
discoverer  of  the  composition  of  water.  Among  the  innumerable  ex- 
periments which  have  confirmed  this  result,  that  made  by  Fourcroy 
and  his  companions,  is  worthy  of  particular  commemoration ;  the 
gases  were  kept  burning  more  than  a  week,  37500  cubic  inches  were 
consumed,  and  fifteen  ounces  of  pure  water  were  obtained  precisely 
equal  in  weight  to  that  of  the  gases  employed. 

The  decomposition  of  water  was  first  effected,  understandingly,  by 
Lavoisier,  in  1783,  by  passing  the  steam  of  water  over  ignited  iron; 
the  increase  of  weight  in  which,  added  to  the  weight  of  the  hydrogen 
gas  obtained,  precisely  equalled  that  of  the  water  decomposed.  The 
iron  is  found  to  be  in  the  same  condition  as  if  it  had  been  burned  in 
oxygen  gas  or  common  air,  it  being  a  protoxide. 


WATER. ITS  PROPERTIES. 


1.  It  absorbs  spontaneously,  a  small  quantity  of  air,  which  escapes 
by  the  action  of  the  air  pump,  or  by  boiling,  and  in  the  Torricellian 
vacuum.  Water  absorbs  oxygen,  rather  than  nitrogen  from  the  air ; 
water  that  has  been  exposed  to  the  air,  contains  over  31  per  cent,  of 
oxygen  ;  this  fits  water  to  support  the  life  of  fishes,  and  gives  it  pun- 
gency and  vivacity  to  the  taste.  The  air  obtained  by  ebullition  from 
rain  water,  contains  32  per  cent,  of  oxygen ;  that  from  snow  water 
34.8,  but  if  the  atmosphere  be  excluded  during  its  melting,  it  is  near- 
ly free  from  air ;  this  is  not  contradictory,  for  during  the  freezing  of 
water,  the  air  is  expelled,  and  is  again  absorbed  when  it  melts.  When 


212  WATER. 

water  absorbs  any  other  gas,  the  air  which  it  contains  is  more  or  less  ex- 
pelled ;  hence,  gases  confined  over  water,  are  soon  contaminated  in 
this  manner.  In  boiling  water,  the  first  portions  expelled  contain  the 
most  oxygen ;  the  nitrogen  comes  more  tardily,  and,  if  after  boiling 
and  air  pump  exhaustion  have  ceased  to  evolve  any  more  gas,  electri- 
cal discharges  be  passed  through  water,  more  nitrogen  will  be  evolved 
along  with  oxygen  and  hydrogen,  proceeding  from  the  decomposition 
of  the  water. 

2.  Boiled  water,  absorbs  a  portion  of  every  gas.* — The  quantity 
absorbed  is  increased  by  pressure  and  by  cold,  and  the  facts  will  be 
more  particularly  stated  in  giving  the  history  of  each  particular  gas. 

3.  Water  always  exists  in  the  atmosphere,  in  the  driest  weather. 

Sa.)  Deliquescent  substances  attract  it,  as  potash,  sulphuric  acid, 
muriate  of  lime. 

(b.)  Cold  bodies  condense  it,  in  dew  or  hoar  frost. 
(c.)  Porous  bodies  absorb  water  from  the  air. — -Dry  earth,  dry  oat 
meal,  and  dry  metallic  filings,  afford  examples. 

4.  Water,  by  combination  becomes  solid. — This  is  seen  in  the  hy- 
drated  alkalies,  potash  and  soda,,  in  the  hydrated  oxides,  and  in  many 
crystals,  especially  artificial  ones  ;  when  crystals  contain  water,  it  is 
always  in  definite  quantity. 

5.  Water,  dissolves  a  great  variety  of  bodies,  more,  probably,  than 
any  other  fluid — acids,  alkalies,  salts,  gum,  sugar,  alcohol,  &c. 

It  is  the  most  general  solvent  to  bring  substances  together,  under 
such  circumstances  as  to  promote  the  various  chemical  processes  of 
nature,  and  as  it  alters  their  properties  very  little,  it  is  favorable  to 
chemical  action  by  bringing  many  solids  into  a  state  of  fluidity.  But 
in  some  cases,  its  chemical  action  is  highly  important. 

6.  The  solution  of  a  solid  in  water  generally  produces  cold. — 
Bi-carbonate  of  potash  and  caustic  potash  crystallized,  produce  cold  ; 
but  caustic  potash  that  has  been  recently  ignited,  or  which  after  that 
operation  has  not  again  absorbed  water,  dissolves  with  a  rise  of  tem- 
perature. 

7.  Jlir  is  disengaged  during  the  solution  of  bodies  in  water. — It  is 
partly  contained  in  the  crevices  of  the  bodies,  and  partly  dissolved  in 
the  water. 

8.  Water,  when  pure,  is  perfectly  transparent,  tasteless,  colorless, 
and  inodorous.     According  to  Professor  Robinson,  a  cubic  foot  of 
water  at  the  temperature  of  55°,  weighs  998. 74f  oz.  Avoirdupois,  or 
62.42  Ibs.     A  cubic  inch  at  60°,  and  at  30  inches  pressure,  weighs 
252.525  grains.     Pure  or  distilled  water,  at  the  temperature  of  60°, 
is  always  taken  as  the  unit,  when  we  speak  of  the  specific  gravity  of 
other  bodies. 


*  See  n  table,  Henry,  Vol.  1,  p,  225.  i  In  round  numbers  1000. 


WATER.  213 

The  refractive  power  of  water  is  very  high,  owing,  as  is  supposed, 
to  the  hydrogen  which  it  contains.  By  a  vigorous  stroke  in  a  syringe, 
water  emits  a  flash  of  light. — Thenard. 

Water  has  generally  been  regarded  as  incompressible,  but  Mr.  Per- 
kins applied  to  it  a  force  of  2000  atmospheres,  and  stated  the  com- 
pression at  y1,-,  but  Prof.  Oersted*  justly  considers  this  estimate  as  far 
too  great.  It  would  appear  from  a  note  by  the  late  Prof.  Fisher,f 
of  Yale  College,  that  the  subject  is  not  quite  new,  and  Mr.  Canton, 
so  far  back  as  1764,  ascertained  that  water  expands  ^TTT  o  Part>  by 
the  removal  of  the  pressure  of  the  atmosphere,  and  that  an  additional 
atmosphere  reduces  its  volume  in  an  equal  degree.  No  natural  water 
is  quite  pure ;  it  always  holds  saline  and  earthy  matters  dissolved  be- 
sides gases;  rain  or  snow  water  obtained  away  from  population,  as  on 
a  mountain,  is  the  purest.  It  is  obtained  pure  by  distillation,  espe- 
cially in  vessels  of  gold,  silver,  or  platinum.  Distilled  water  is  indis- 
pensable in  all  accurate  chemical  operations. 

8.  Utility  of  water. — It  is  far  more  abundant  than  all  other  fluids  ; 
it  is  indispensable  to  animal  and  vegetable  life,  and  no  other  fluid 
would  answer  the  same  purposes. 

Water  enters  into  the  composition  of  all  the  solids  and  fluids  which 
we  consume  for  food  and  drink ;  it  imparts  that  humidity  to  the  air 
which  in  breathing  moderates  animal  heat ;  it  affords  by  its  pressure 
and  motion,  the  means  of  great  mechanical  operations,  and  it  facilitates 
commerce  and  friendly  communication  between  nations.  It  is  ne- 
cessary that  its  properties  should  be  negative,  or  it  would  be  injurious. 

Gazometer  for  oxygen  or  any  gas  not  absorbed  by  water. — Dr.  Hare. 

"  The  engraving  on  p.  214,  represents  a  section  of  the  gazometer 
for  oxygen,  which  is  capable  of  holding  between  five  and  six  cubic 
feet  of  gas.  It  is  placed  in  the  cellar  beneath  the  lecture  room.  The 
wooden  tub,  V,  is  necessarily  kept  nearly  full  of  water.  The  cylin- 
drical vessel,  T,  of  tinned  iron,  is  inverted  in  the  tub,  and  suspended 
and  counterpoised,  by  the  rope  and  weight,  in  such  manner,  as  to  re- 
ceive any  gas  which  may  proceed  from  the  orifice  of  the  pipe,  in  its 
axis.  This  pipe  passing,  by  means  of  a  water-tight  juncture,  through 
the  bottom  of  the  tub,  rises  through  the  floor,  F,  is  furnished  with  a 
cock  at  C,  and  terminates  in  a  gallows  screw.  This  is  fixed  in  a 
cavity  made  in  the  plank  forming  the  table  of  the  lecture  room,  in  the 
vicinity  of  the  pneumatic  cistern.  Hence  by  means  of  it,  and  a  lead- 
en pipe  soldered  to  a  brass  knob,  properly  perforated,  a  communica- 
tion may  be  established  between  the  cavity  of  the  gazometer,  and  any 
other  vessel,  for  the  purpose  either  of  introducing  or  withdrawing  the 
gas.  The  counter-weight  being  made  heavier  than  the  vessel,  by 
appending  additional  weight  to  the  ring,  K,  the  gas  may  be  sucked 

*  Edin.  Jour.  No.  12,  p.  201.  t  Am.  Jour.  Vol.  Ill,  p.  347. 


214 


WATER. 


in  from  a  bell  glass,  (situated  over  the  pneumatic  cistern,)  as  fast 
as  it  enters  the  bell,  from  the  generating  apparatus." 

"  Gazometers  which  contain  40  or  50,000  cubic  feet,  have  been 
constructed  upon  this  principle,  for  holding  the  gas  from  oil  or  coal." 


l"V 


WATER.  215 

Deutoxide  of  Hydrogen. 

1 .  HISTORY. — Until  1818,  water  was  believed  to  be  the  only  com- 
pound of  hydrogen  and  oxygen  ;  but  in  that  year,  Thenard  published 
in  the  Transactions  of  the  Academy  of  Sciences  of  Paris,*  an  ac- 
count of  this  singular  substance,  and  hitherto  little  has  been  added 
to  the  facts  stated  in  the  original  memoirs  by  this  celebrated  chemist. 

2.  PREPARATION. f — From  the  peroxide  of  barium,  by  the  action 
of  diluted  muriatic  acid,  and  then  of  sulphuric  acid,  both,  a  number 
of  times  repeated ;  followed  by  that  of  sulphate  of  silver,  and  then  by 

*  Thenard's  Chem.  4th  Ed.  Vol.  V,  p.  41. 

t  The  principal  steps  of  this  complicated  process,  which  the  student  will  not  be  ex- 
pected fully  to  understand  until  farther  advanced,  are  as  follows : — 

1.  Prepare  nitrate  of  baryta ;  this  may  be  done  by  decomposing  the  sulphate  ot 
barytes  by  igniting  it  with  charcoal,  by  which  it  is  turned  into  a  sulphuret;  this  is 
decomposed  even  in  an  iron  vessel  by  nitric  acid,  and  any  iron  that  is  taken  up  is 
precipitated  by  baryta,  and  the  nitrate  of  baryta  is  then  crystallized. 

2.  The  nitrate  is  decomposed  by  ignition  in  a  porcelain  retort ;  (if  the  heated  ni- 
trate be  withdrawn  from  the  fire  in  proper  time,  it  will  be  left  in  the  state  of  a  fine 
deutoxide,  but*)  it  is  commonly  oxygenized  by  passing  the  dry  pure  oxygen  gas  over 
the  ignited  baryta  contained  in  a  luted  glass  tube  ;  the  oxygen  is  rapidly  absorbed, 
and  we  obtain  the  deutoxide  or  peroxide  of  barium  ;  it  is  this  very  portion  of  oxygen 
thus  absorbed,  which  is  to  be  transferred  to  water  or  rather  to  its  hydrogen,  and  it  is 
done  in  the  following  manner. 

3.  Take  water,  six  or  seven  ounces,  and  strong  muriatic  acid  sufficient  to  dissolve 
230  grains  of  baryta,  and  add  185  grains  of  powdered  peroxide  of  barium ;  the  so- 
lution is  without  effervescence,  because,  although  the  acid  combines  only  with  the 
protoxide,  the  excess  of  oxygen  is  not  disengaged,  but  unites  to  the  water  or  to  the 
hydrogen  of  the  water ;  the  water  thus  becomes  oxygenized,  but  in  too  small  a  pro- 
portion to  be  observed. 

4.  Sulphuric  acid  is  now  added,  just  enough  to  precipitate  the  barytes,  and  the  muri- 
atic acid  is  thus  liberated,  and  is  again  ready  to  act  upon  more  of  the  peroxide,  which, 
as  before,  is  now  added  in  the  proportion  of  185  grains;  this  is  dissolved;  the  excess 
of  oxygen  is  added  to  the  water  ;  the  barytes  is  again  precipitated  by  sulphuric  acid, 
and  the  insoluble  sulphate  is  separated  by  the  filter ;  thus  the  process  is  repeated  a 
sufficient  number  of  times,  until  about  three  ounces  of  the  peroxide  have  been  em- 
ployed, when  the  liquid  will  contain  from  twenty  five  to  thirty  times  its  volume  of 
oxygen  gas. 

5.  The  solution  is  now  a  mixture  of  muriate  of  baryta  with  oxygenized  water,  and 
to  remove  the  salt,  its  acid  is  first  separated  by  sulphate  of  silver,  which  forms  mu- 
riate of  silver,  and  liberates  the  sulphuric  acid,  which,  in  its  turn,  is  removed  by  so- 
lid baryta  in  powder  and  by  filtration. 

6.  The  solution  is  now  the  oxygenized  water,  or,  as  it  is  more  properly  called,  the 
peroxide  of  hydrogen,  but  still  containing  more  water  than  is  necessary  for  its  solu- 
tion ;  this  is  removed  by  the  air  pump ;  the  vessel  containing  the  peroxide  of  hydro- 
gen is  placed  in  another  about  two  thirds  full  of  sulphuric  acid,  and  the  vacuum  is 
formed  over  it,  which  occasions  the  evaporation  of  the  water,  and  leaves  eventually 
nothing  but  the  peroxide,  which,  if  continued  in  the  vacuum,  is  finally,  but  very 
slowly  volatilized  unchanged.     Thenard  says,  "  au  bout  de  deux  jours  la  liqueur 
contiendra  peut-etre  deux  cent  cinquante  fois  son  volume  d'  oxygene."     The  per- 
oxide, as  thus  obtained,  has  the  specific  gravity  of  1.452,  and  it  did  not  grow  any 
denser  by  continued  exposure  to  the  vacuum,  although  it  diminished  considerably 
in  quantity. 

Minute  as  this  abridged  statement  may  appear,  there  are  many  details  necessary 
to  success,  for  which  recourse  must  be  had  to  Thenard's  own  account  in  his  Chem- 
istry, or  in  the  Ann.  de  Chim.  et  de  Phys.  Veils.  VIII,  IX  and  X ;  or  Ann.  of  Phil. 
Vols.  XIII  and  XIV. 

*  The  clause  in  parenthesis  communicated  by  Dr,  J.  Torrey. 


216  WATER. 

baryta,  and  finally  by  concentration  by  air  pump  exhaustion,  aided 
by  the  affinity  of  the  vapor  of  water  for  sulphuric  acid. 

3.  PROPERTIES. 

(a.)  They  are  remarkably  different  from  those  of  water. — The 
fluid  is  colorless  and  inodorous  ;  destroys  gradually  the  color  of  litmus 
and  turmeric  paper  ;*  is  somewhat  corrosive  to  the  skin,  bleaches  it, 
and  if  abundantly  applied,  destroys  it.  It  bleaches  the  tongue, 
makes  it  tingle,  and  gives  a  peculiar  taste  resembling  that  of  metallic 
solutions. 

(b.)  Although  much  more  fixed  than  water,  it  may  be  entirely  evap- 
orated in  a  vacuum,  without  decomposition.  At  59°  Fahr.  it  is  de- 
composed into  water  and  oxygen  gas.  It  can  therefore  be  scarcely 
preserved  except  surrounded  by  ice  ;  but  it  remained  fluid  at  every 
degree  of  cold  applied  to  it. 

(c.)  At  212°,  it  is  decomposed  explosively,  oxygen  gas  being  lib- 
erated, and  therefore  if  we  would  decompose  it  by  heat,  it  must  be 
previously  diluted.  Diffuse  day  light  has  no  effect  upon  it,  and  di- 
rect solar  light  very  little. 

(rf.)  It  is  decomposed  by  nearly  all  the  metals,  and  by  most  of  their 
oxides,  these  substances  being  in  a  state  of  minute  division. 

(e.)  Those  that  powerfully  attract  oxygen  combine  with  a  portion 
of  it;  such  are  potassium,  sodium,  arsenic,  zinc,  &ic.  and  in  this  way 
several  metallic  protoxides  become  peroxides,  and  on  the  same  prin- 
ciple hydriodic  acid,  sulphurous  acid  and  sulphuretted  hydrogen,  at- 
tract oxygen  from  this  fluid  and  bring  it  to  the  condition  of  water. 

(/.)  Oxide  of  silver]-  decomposes  the  oxygenized  water  with  ex- 
plosion.— This  happens  if  the  fluid  falls  on  the  silver,  drop  by  drop, 
and  if  the  place  be  dark,  light  is  seen. 

(g.)  Several  other  peroxides  decompose  this  oxygenized  compound. 
— Such  are  those  of  manganese,  cobalt,  lead,  platinum,  gold,  iridium, 
rhodium,  and  palladium ;  the  oxygen  of  the  water  is  always  disen- 
gaged, and  sometimes  that  of  the  oxide.  The  decomposition  is 
complete  and  instantaneous,  and  sometimes  ignition  is  produced  in 
the  glass  tube  containing  the  materials. 

*  Some  have  supposed  that  the  bleaching  powers  of  chlorine  may  depend  on  the 
mixture  with  it,  of  a  small  quantity  of  oxygenized  water. 

t  In  the  Am.  Jour.  Vol.  XVII,  p.  34,  Dr.  Ed.  W.  Faust  has  suggested,  that  this 
curious  phenomenon  of  the  decomposition  of  oxygenized  water  by  oxide  of  silver, 
may  be  accounted  for  upon  galvanic  principles :  thus 

"When  any  metal  is  placed  in  the  peroxide  of  hydrogen,  a  galvanic  effect  is  pro- 
duced. The  hydrogen  having  less  affinity  for  the  excess  of  oxygen,  than  the  metal 
has,  the  liquid  becomes  negative,  thus  acting  the  part  of  the  copper  plate  of  a  bat- 
tery, while  the  metal  becomes  positive,  supplying  the  place  of  the  zinc  plate.  The 
liquid  is  thus  resolved  into  water  and  oxygen.  If  the  metal  be  very  oxydable,  it 
retains  the  oxygen,  which  is  evolved  if  gold,  platina,  &c.  be  used.  We  need  scarce- 
ly refer  to  the  wires  of  a  battery,  for  a  parallel  case. 

"  When  the  peroxide  of  hydrogen  conies  in  contact  with  the  oxide  of  silver,  the 
oxygen  escapes  from  both,  and  the  latter  is  reduced  to  the  metallic  state."  Far  a 
fuller  account,  see  the  paper  of  Dr.  Faust. 


WATER. 

(h.)  Water  and  acids,  especially  the  more  powerful,  render  the 
compound  more  permanent :  if  the  liquid  has  begun  to  effervesce  by 
heat,  a  drop  of  the  stronger  acids,  and  even  of  the  principal  vegeta- 
ble acids,  will  cause  it  to  cease,  and  the  addition  of  an  alkali  will 
cause  the  effect  to  be  renewed. 

(i.)  Peroxide  of  hydrogen  is  decomposed  by  heating  carefully  the 
diluted  solution:  its  composition  as  ascertained  by  its  discoverer, 
Thenard,  is  hydrogen  1  proportion  and  oxygen  2  =  16,  and  17  is  there- 
fore its  representative  number.  From  its  great  specific  gravity,  it 
sinks  in  common  water  as  sulphuric  acid  does,  although  it  has  a  great 
affinity  for  that  fluid. 

Thenard  suggested  an  application  of  it  to  remove  dark  spots  from 
pictures,  in  which  white  lead  paint  had  become  tarnished  by  sulphuret- 
ted hydrogen :  this  it  effected  instantly  by  the  agency  of  the  oxygen  of 
the  oxygenized  water,  which  converted  the  sulphuret  into  a  sulphate. 

Many  other  particulars  might  be  added  respecting  this  curious  com- 
pound, but  they  would  be  inconsistent  with  the  extent  of  this  work. 
There  does  not  appear  any  positive  proof  that  the  combination  of  the 
oxygen  is  with  the  hydrogen  directly,  rather  than  with  the  entire  water, 
but  the  fact  that  the  oxygen  bears  a  multiple  relation  to  that  contained 
in  water,  affords  a  strong  presumptive  proof;  perhaps  a  satisfactory 
one,  in  support  of  the  former  view. 

EUDIOMETRY  BY  HYDROGEN. 

Eudiometry  has  been  already  mentioned  in  giving  the  history  of 
the  atmosphere,  and  it  remains  to  describe,  as  fast  as  we  come  to 
them,  the  action  of  the  various  substances  that  operate  to  remove 
oxygen  from  the  air,  or  from  any  mixture  of  gases.  Hydrogen  is 
one  of  the  most  effectual. 

1 .  Modes  of  application. 

(«.)  In  a  common  eudiometer  tube. — This  kind  of  tube  is 
made  very  stout,  as  in  the  annexed  figure :  the  glass  is  well  ©.  .. 
annealed,  its  mouth  is  usually  trumpet  shaped,  it  is  graduated 
and  furnished,  towards  the  top,  with  two  wires,  cemented  into 
the  glass,  and  approaching,  but  not  touching  each  other.  In 
this  manner,  an  electric  spark  is  easily  made  to  pass  through 
the  mixed  oxygen  and  hydrogen  gases,  and  an  explosion  and 
diminution  of  volume  follow. 

(b.)  Dr.  lire's  eudiometer,  of  which  a  figure  is 
annexed,  is  very  simple.  It  is  a  syphon  tube,  clos-. 
ed  at  one  end,  and  with  platinum  wires  hermetically 
inserted :  it  is  of  course  graduated :  its  legs  are  both 
from  six  to  nine  inches  long,  and  the  interior  diame-. 
ter  is  from  two  to  four  tenths  of  an  inch :  it  will  receive 
safely  one  fourth  of  an  inch  of  the  mixed  oxygen 
and  hydrogen  gases,  and  nearly  an  equal  volume  of 
olefiant  gas  mixture :  the  water  or  mercury  in  the 

28 


218 


WATER. 


bend  is  brought  to  the  same  level,  and  two  inches  or  more  of  air  is 
left  in  the  leg,  which  is  held  in  the  hand.  The  thumb  is  pressed 
firmly  upon  the  orifice,  and  the  spark  taken  either  through  the  hand 
as  a  part  of  the  conducting  substance,  or  by  a  wire :  the  elastic  spring 
of  the  confined  air  prevents  all  danger  of  explosion,  only  a  very  slight 
pressure  being  felt  at  the  moment.* 

(c.)  Volttfs  eudiometer. — I  give,  from 
Dr.  Hare,  a  figure  of  this  elegant,  but 
expensive,  and  rather  complicated  in- 
strument, which  is  now  little  used,  and  I 
therefore  omit  the  detailed  description, 
which  may  be  found  in  Dr.  Hare's  Com- 
pendium. 

A  and  G  are  graduated  glass  tubes : 
each  division  of  the  200  parts  of  A  cor- 
responding to  10  of  G,  which  holds  10 
measures  of  A.  C  is  a  funnel-shaped 
foot,  with  a  stop  cock  and  cap  for  intro- 
ducing gas  from  the  measure,  k,  which 
is  furnished  with  a  slide  so  as  to  give  al- 
ways the  same  measure.  I  is  an  insu- 
lated electrical  conductor.  F,  a  basin 
shaped  cap  for  pouring  in  water,  and  to 
admit  of  introducing  G,  air  tight,  with  a 
finger  on  the  orifice,  so  that  (F  being 
filled  with  watery)  it  may  be  screwed  to 
its  place,  or  removed  from  it  without  loss 
of  its  contents.  There  is  of  course  a 
communication  through  B  and  E,  and 
the  whole  apparatus  having  been  first 
filled  with  water,  the  mixed  gases  are 
introduced ;  the  spark  taken ;  B  opened 
under  water  to  ascertain  the  diminution, 
and  the  residual  gas  being  let  up  into  G 
is  there  accurately  measured. 

(d.)   Dr.  Hare's    eudiometer. To 

produce  the  explosion  of  the  gases,  this 
gentleman  has  availed  himself  of  the  ig- 
nition produced  by  a  small  calorimeter, 
in  a  slender  platinum  wire,  forming  a  part  of  the  connexion  in  the 
interior  of  the  eudiometer  tubes :  he  measures  the  gas  conveniently 
and  accurately,  by  a  graduated  rod,  sliding  air  tight  in  the  instrument, 


*  For  a  more  detailed  description,  see  lire's  Dictionary,  art.  Eudiometer;   also 
Edin.  Phil,  Trans.  Jan.  1818, 


WATER. 


219 


and  also  by  some  separate  instruments  called  volumeters,  and  sliding 
rod  gas  measures.  To  one  of  his  eudiometers  a  barometer  gage  is 
attached,  by  which  the  amount  of  absorption  is  accurately  ascertain- 
ed. The  ignition  of  the  platinum  by  the  calorimotor,  for  the  purpose 
of  inflaming  the  gases,  is  an  elegant  and  novel  method  of  operating  ; 
the  various  modes  of  measuring  the  gases  are  ingenious  and  accur- 
ate, and  the  detailed  description  of  all  the  instruments  and  operations 
may  be  found  in  Dr.  Hare's  Compendium,  and  in  the  Am.  Journal. 
We  subjoin  the  figure,  and  an  abridged  description  of  the  simplest 
of  these  eudiometers. 

Hydro-oxygen  Eudiometer  of  Dr.  Hare. 


A  A 


W    W 

W  W  Two  brass  wires  passing  through  the  socket  S,  and  appear- 
ing within  the  glass  detonating  tube  G,  where  they  are  connected  at 
the  top  by  a  soldered  arc  of  platina  wire,  visible  in  the  drawing. 
One  of  the  brass  wires  is  soldered  to  the  socket.  The  other  is  fast- 
ened by  means  of  a  collar  of  leathers,  packed  by  a  screw,  so  that  it 
has  no  metallic  communication  with  the  other  wire,  unless  through 
the  filament  of  platinum,  which  is  called  the  igniting  wire. 

At  A  is  a  capillary  orifice  in  the  glass  tube,  which  is  opened  and 
closed  by  the  lever  and  spring,  seen  in  the  drawing,  and  it  may  be 
guarded  by  a  gallows  screw,  in  the  iron  staple  A  A,  which  may  be  ap- 
pended to  the  instrument  by  pivots  at  S,  and  the  opposite  point,  and 
may  be  dropped  out  of  the  way  when  the  eudiometer  is  to  be  charged. 

R  The  sliding  rod,  is  acurately  graduated  to  about  160°,  and  to 
diminish  the  chance'  of  leakage,  a  stop  cock  may  be  interposed  be- 
tween the  sliding  rod  and  the  detonating  tube. 

B  represents  a  detonating  tube,  to  be  discharged  by  an  electric 
spark ;  it  may  be  screwed  into  the  socket  S,  instead  of  the  tube  G. 


220  WATER. 

The  sliding  rod  eudiometer  being  ascertained  to  be  tight,  is  filled 
with  water,  free  from  air  bubbles,  the  rod  being  introduced  to  its 
hilt,  and  the  valve  at  A  being  open,  the  rod  is  drawn  out  and  the 
instrument  being  in  the  atmosphere,  common  air  of  course  en- 
ters, or  the  eudiometer  is  placed  under  a  bell  glass,  and  the  gas- 
es, either  successively,  or  previously  mixed  in  the  proper  propor- 
tions, are  then  introduced  by  suction  of  the  graduated  rod  A,  and 
the  wires  W  W  being  applied  to  the  two  poles  of  a  calorimotor, 
at  the  moment  in  action,  the  explosion  takes  place.  The  valve  be- 
ing opened  under  water,  this  fluid  enters  to  supply  the  place  of  the 
gases  consumed,  and  any  residuary  air  being  excluded  by  the  sliding 
rod,  the  portion  of  the  latter  remaining  without,  will,  by  the  gradua- 
tion, indicate  the  deficit,  which  is  to  be  apportioned  by  the  rules  given 
below ;  that  is,  f  of  the  diminution  is  hydrogen,  and  £  is  oxygen.* 

For  the  purpose  of  the  general  student,  any  mode  in  which  the 
mixed  gases  can  be  exploded  conveniently  and  the  diminution  easily 
ascertained,  will  answer  every  valuable  purpose. 

USE    OF    THE    HYDRO-OXYGEN    EUDIOMETER. 

If  we  mix  accurately  2  volumes  of  hydrogen  with  1  of  oxygen, 
and  inflame  them  in  any  of  the  above  named  eudiometers,  provided 
the  gases  are  pure,  there  will  be  a  total  condensation. 

As  it  is  however  rare  that  the  gases  are  quite  pure,  it  is  often  best 
to  employ  an  excess  of  that  gas  which  is  used  to  detect  the  other. 
In  examining  oxygen  gas,  if  we  take  three  volumes  of  hydrogen, 
one  third  of  the  diminution  being  oxygen,  it  will  not  injure  the  result, 
if  there  should  be  a  residuum.  If  100  measures  of  oxygen  gas  are 
fired  with  300  hydrogen,  and  there  is  a  residuum  of  130,  it  follows 
that  270  have  disappeared,  and  90  is  one  third  of  this,  and  of  course 
it  appears  that  there  is  10  per  cent,  of  foreign  gas,  it  may  be  nitrogen, 
or  carbonic  acid  ;  for  there  is  an  excess  of  100  of  hydrogen. 

Suppose,  on  the  other  hand,  that  we  fire  equal  measures  of  oxy- 
gen and  hydrogen,  say  100  of  each;  if  the  200  are  reduced  to  80, 
the  diminution  will  have  been  120,  and  two  thirds  of  this,  that  is  80, 
is  owing  to  hydrogen  ;  it  follows  of  course,  that  there  is  in  the  hy- 
drogen 20  per  cent  of  foreign  gas  most  probably  nitrogen. — Henry. 

If  100  measures  of  common  air  are  mingled  with  50  of  hydrogen, 
and  exploded,  the  50  volumes  will  generally  be  reduced  to  87,  giv- 
ing a  diminution  of  63  measures,  one  third  of  which,  21,  is  the  pro- 
portion of  oxygen  usually  assigned  to  the  atmosphere. 

*  The  figure  of  the  calorimotor  used  in  these  experiments  will  he  given  under 
the  head  of  Galvanism.  For  a  more  detailed  account,  and  various  particulars  to  in- 
sure accuracy,  see  Dr.  Hare's  Compendium. 

Not  being  in  possession  of  the  wood  cuts  of  the  barometer  gage  eudiometer,  and 
of  the  sliding  rod  gas  measure,  I  have  been  obliged  to  omit  an  account  of  those  in- 
struments which  1  had  prepared. 


WATER. 

Dr.  Thomson  (First  Principles,)  employed  42  volumes  of  hy- 
drogen to  100  of  air,  and  always  obtained  a  reduction  of  60,  one 
third  of  which,  20,  corresponds  with  the  theory  of  volumes,  and  also 
of  multiple  proportions  by  weight,  and  granting  that  atmospherical 
air  is  a  feeble  compound,  this  would  appear  to  be,  in  all  probability, 
the  true  proportion ;  and  if  this  is  the  true  proportion,  this  fact  in  its 
turn  strengthens  very  much  the  opinion  that  in  the  atmosphere,  the 
elements  are  not  merely  mixed,  but  slightly  combined. 

The  electric  spark  will  no  longer  cause  explosion  in  the  mixture 
of  2  volumes  of  common  air,  and  1  of  hydrogen  gas,  when  there  are 
12  parts  of  common  air,  or  9  of  hydrogen  added  to  the  mixture,  or 
when  it  is  rarefied  16  times  by  diminution  of  pressure,  or  6  times  by 
heat.  Oxygen  and  hydrogen  gases  in  the  proportion  to  form  water, 
if  rarefied  mechanically  1 8  times,  will  not  explode  by  electricity ; 
according  to  Sir  H.  Davy,  rarefaction  by  heat  causes  the  mixed 
gases  to  explode  more  readily  by  the  temperature  of  ignition. 

In  the  analysis  of  atmospheric  air  by  hydrogen  gas,  5  volumes 
of  air  should  be  , sufficient  for  2  of  hydrogen;  but  it  is  better  to 
employ  a  small  excess ;  here,  as  before,  one  third  of  the  dimi- 
nution will  be  owing  to  oxygen.  Dr.  Hare  says,  that  in  a  great 
number  of  experiments,  performed  by  means  of  his  instruments,  he 
obtained  very  constantly  20.66  as  the  quantity  of  oxygen  in  100 
parts  of  the  air,  and  that  in  twenty  experiments,  the  greatest  discord- 
ance did  not  amount  to  ToVo-  m  100  measures  of  air. —  Comp. 

ACTION   OF  PLATINUM. 

(a.)  A  very  effectual  eudiometer  was  unexpectedly  presented  to 
us  by  a  discovery  of  Dobereiner,  of  Jena.  The  muriate  of  platinum 
and  ammonia,  when  ignited,  leaves  the  metal  in  the  state  of  spongy 
platinum,*  upon  which,  if  a  stream  of  hydrogen  be  directed,  the  metal, 
if  air  has  access,  becomes  ignited,  and  the  gas  soon  takes  fire. 

(6.)  It  is  necessary  that  the  oxygen  gas  of  the  air  be  let  in  at  the 
same  time,  and  water  is  the  result,  as  if  the  gases  had  been  kindled 
in  any  other  way. 

(c.)  If  spongy  platinum  be  introduced  into  a  mixture  of  oxygen,  or 
common  air,  with  hydrogen  gas,  in  explosive  proportions,  they  de- 
tonate ;  in  other  proportions  they  slowly  combine  and  form  water. 

(d.)  The  spongy  platinum  being  formed  into  a  paste,  with  about  an 
equal  weight  of  alumine,  or  china  clay,  and  water,  with  the  addition 
of  some  muriate  of  ammonia,  to  preserve  the  porosity,  and  made  into 

*  Or  the  sub-oxide  of  platinum,  prepared  by  Mr.  E.  Davy's  process,  answers,  per- 
haps equally  well. 

t  See  Henry,  Vol.  I.  p.  238,  and  Ann.  de  Chimie  et  de  Phys.  23,  and  24. 


WATER. 

balls  of  the  size  of  peas,  and  dried,  at  first  slowly,  and  afterwards 
more  rapidly,  the  balls  will  act  in  the  same  manner  as  the  sponge, 
and  their  power  is  renewed  by  heating  them  in  the  blowpipe  flame  ; 
being  thus  treated,  they  will,  if  preserved  from  dust,  answer  a 
thousand  times,  and  more ;  their  size  need  not  be  over  2,  4,  or  6 
grains.  If  one  of  the  balls,  fastened  for  convenience,  to  a  piece  of 
platinum  wire,  be  introduced  into  a  mixture  of  air  100,  and  hydro- 
gen gas  50  measures,  it  will  in  a  few  minutes  be  reduced  to  87 ;  the 
diminution,  63,  divided  by  3=21,  the  proportion  of  oxygen. 

(jf.)  In  general,  the  platinum  at  common  temperatures  does  not 
act  upon  the  gases  that  are  found  mixed  with  hydrogen ;  but  if  the 
ball  is  hot,  it  sometimes  acts  upon  the  residuary  nitrogen  to  form 
ammonia,  and  produces  a  diminution  greater  than  63. 

(g.)  Moist  platinum  sponge  has  the  same  power  as  dry,  only  it  re- 
quires a  longer  time.  If  some  of  the  ammonio-muriate  of  plati- 
num be  ignited  in  the  sealed  end  of  a  glass  tube,  or  if  its  solution  be 
decomposed  there,  by  a  rod  of  zinc,  a  thin  film  of  the  metal  will  ad- 
here firmly  to  the  interior  of  the  tube.  In  such  a  tube,  a  mixture  of 
oxygen  and  hydrogen,  or  of  the  latter  and  common  air,  will  be  de- 
composed in  a  few  hours  :  and  if  the  hydrogen  prevail,  all  the  oxy- 
gen will  disappear ;  in  this  manner  hydrogen  can  be  perfectly  puri- 
fied from  oxygen ;  even  one  part  in  100  will  be  abstracted,  which  much 
exceeds  the  power  of  hydrogen  alone,  aided  by  the  electric  spark. 

(A.)  Dobereiner  supposed  this  to  be  a  peculiar  galvanic  arrange- 
ment, in  which  the  hydrogen  represents  the  zinc,  and  the  platinum 
the  copper ;  but  it  appears  that  no  heat  is  produced,  unless  oxygen 
or  atmospheric  air  is  present ;  so  that  the  office  of  the  metal  appears 
to  be  to  produce  a  combustion  of  the  hydrogen. 

(i.)  Platinum,  in  fine  powder,  produces  no  action,  not  even  a  slow 
one ;  the  laminated  metal  and  its  wire  are  equally  inert,  but  thicker 
leaves  and  wire  acted,  although  slowly,  when  heated  to  between 
200°  and  300°,  Centigrade.  A  very  thin  film  of  platinum,  rolled 
round  a  glass  tube,  or  suspended  freely  in  a  detonating  mixture,  pro- 
duced no  effect  in  several  days ;  but  when  crumpled  like  the  wad- 
ding of  a  gun,  it  produced  instant  detonation. 

(j.)  Platinum  sponge  strongly  ignited,  loses  the  property  of  becom- 
ing incandescent ;  but  produces  slowly,  and  almost  imperceptibly,  the 
combination  of  the  two  gases. 

(k.)  This  phenomenon  appears  still  more  remarkable,  when  it  is 
considered  that  it  happens  between  the  lightest  and  the  heaviest  body 
known. 

(L)  If,  upon  a  mixture  of  spongy  platinum,  and  nitrate  of  platinum, 
and  ammonia,  a  jet  of  hydrogen  be  directed,  the  mixture  reddens, 
crackles,  and  emits  inflamed  sparks. 


WATER.  223 

(m.)  Alcohol  is  turned  into  acetic  acid  and  water,  by  the  action  of 
the  sulphuretted  oxide  of  platinum  ;*  the  same  effect  is  produced  by 
the  black  powder  which  zinc  precipitates  from  the  platinum  solution. 

(n.)  Several  metals  act  in  a  similar  manner  upon  mixtures  of  oxy- 
gen and  hydrogen ;  among  them,  palladium  is  the  most  effectual ; 
this  metal,  and  iridium  inflamed  the  mixed  gases  at  common  tempe- 
ratures, and  gold  and  silver  acted  efficiently  at  a  heat  below  212°, 

Modes  of  preparing  Platinum  sponge. 

(a.)  According  to  my  own  experience,  when  common  crude  gram 
platinum  is  dissolved  in  nitro-muriatic  acid,  and  precipitated  by  muriate 
of  ammonia ;  this  orange  precipitate  being  collected  by  subsidence,  may 
be  partially  dried  in  a  Wedgwood's  or  other  dish,  and  then  transfer- 
red into  a  platinum  crucible,  which  may  be  gradually  heated  in  a 
little  earthen  furnace,  till  the  fumes  of  muriate  of  ammonia  cease 
to  appear.  The  cover  of  the  crucible  may  now  be  put  on,  and  the 
whole  buried  in  burning  coals,  which  may  be  blown  by  hand  bellows, 
both  above  and  below,  until  it  is  fully  ignited ;  it  need  remain  in  this 
state  not  more  than  two  or  three  minutes,  when  it  may  be  withdrawn 
and  cooled. 

(b.)  The  orange  precipitate  maybe  thrown  upon  a  filter,  the  filter 
dried,  and  introduced  directly  into  the  crucible.  A  greater  division 
of  the  platinum  takes  place  in  consequence  of  the  mixture  with  the 
carbon  of  the  burnt  paper,  and  causes  the  platinum  to  ignite  more 
readily  in  a  jet  of  hydrogen  ;  neither  is  there  any  waste  of  the  pre- 
cipitate, f 

(c.)  If  a  stream  of  hydrogen  from  the  compound  blowpipe,  or 
other  jet,  fall  upon  the  sponge,  it  will  be  ignited,  and  the  hydrogen 
will  take  fire.J 

(d.)  If  the  oxygen  be  let  in  at  the  same  time,  or  immediately  af- 
ter, the  mixed  gases  are  instantly  lighted  with  a  slight  explosion. 

*  Procured  by  precipitating  the  muriate  of  platinum  by  sulphuretted  hydrogen-. 

t  The  above  circumstance  was  observed  in  the  laboratory  of  Yale  College,  by  Mr. 
C.  U.  Shepard,  and  noted  Feb.  17,  1827.  In  the  Journal  of  the  Royal  Institution, 
for  April,  1829,  it  is  mentioned  that  Mr.  Pleischel  recommends  that  a  piece  of  paper 
be  three  times  immersed  in  the  solution  of  murrate  of  platinum,  and  then  burnt,  which 
leaves  the  platinum  in  the  best  state  for  producing  ignition.  The  Editors  of  the  Jour- 
nal say,  that  a  little  of  the  ammonio-muriate  of  platinum  being  heated  upon  platinum 
foil,  in  a  spirit  lamp,  with  the  mildest  heat  that  will  dissipate  every  thing  volatile,, 
the  platinum  will  be  left  in  a  fit  state  to  inflame  a  mixture  of  oxygen  and  hydrogen, 
at  the  lowest  possible  temperature. 

Dr.  Webster  recommends  dipping  a  cotton  cloth  in  the  solution  of  the  muriate  of 
platinum,  and  then  burning  it  to  tinder,  which,  if  kept  dry,  will  ignite  as  readily  as 
the  sponge. 

t  This  contrivance  is  so  good  a  substitute  for  the  complicated,  although  elegant  in- 
strument of  Volta,  in  which  a  jet  of  hydrogen  is  fired  by  a  spark  from  an  electropho- 
rus,  that  I  have  not  thought  it  best  to  give  a  drawing  and  description  of  this  instru- 
ment, both  of  which  may  be  seen  in  Dr.  Hare's  Compendium,  p.  65. 


224  COMPOUND  BLOWPIPE. 

(e.)  These  facts  are  best  exhibited  in  public,  by  placing  the  pla- 
tinum in  a  wine  glass,  but  as  it  is  liable  to  break  from  the  sudden 
heat,  it  is  well  to  place  a  dish  beneath. 

(/.)  After  precipitation  of  the  orange  precipitate,  the  yellow  su- 
pernatant fluid  still  contains  platinum,  as  is  indicated  by  muriate  of 
tin  and  hydriodic  acid — on  evaporation,  a  solid  is  obtained,  consisting 
principally  of  the  muriate  of  ammonia,  and  probably  the  foreign  met- 
als ;  for  on  heating  this  residuum  in  a  platinum  crucible,  as  in  the  case 
of  the  sponge,  a  little  metallic  matter  is  obtained,  which,  however, 
does  not  ignite  the  hydrogen. 


1.  Dr.  ROBERT  HARE,  of  Philadelphia,  invented  this  instrument 
in  1801 ;  and  in  December  of  that  year,  the  discovery  was  com- 
municated to  the  chemical  society  of  that  city;  in  1802,  an  account 
of  it  was  published  in  a  pamphlet.*1     It  was  used  by  Dr.  Hare  and 
the  author  of  this  work,  in  1802 — 3,  and  full  accounts  of  their  experi- 
ments were  published  in  the  Phil.  Trans,  of  Philadelphia,  Vol.  VI. 
In  Dec.  1811,  an  extensive  series  of  experiments  was  performed  by 
the  author,  and  published  in  1812,  in  Dr.  Bruce's  Journal,  several 
years  before  Dr.  Clarke's  experiments  were  performed. j- 

2.  Dr.  Hare  is  entitled  exclusively  to  the  merit  of  the  discovery. 
The  contrivance  of  mixing  the  gases  before  hand  in  explosive  pro- 
portions, is  all  that  has  been  added,  and  this  is  not  an  improvement; 
it  introduces  a  serious  danger  where  there  was  none  before,  and  as 
regards  the  heat  produced,  is  attended  with  no  important  advantage. 

3.  The  principle  of  Dr.  Hare's  instrument  is,  that  the  oxygen  and 
hydrogen  gases  coming  from  distinct  reservoirs,  mingle  at  the  mo- 
ment of  their  exit  from  a  capillary  orifice,  and  are  there  ignited  with 
perfect  safety. 

4.  Dr.  Hare  first  ascertained,  that  oxygen  and  hydrogen  gases 
can  be  made  to  burn  together  in  this  manner;  that  the  heat  thus 
evolved,  surpasses  that  produced  by  any  other  mode  of  combus- 
tion, and  that  it  is  scarcely  exceeded  even  by  that  produced  by  Vol- 
taic electricity ;  this  might  perhaps  have  been  anticipated  from  the 
great  capacity  of  the  gases,  especially  of  hydrogen  for  heat.J 

*  Which  was  republished  in  Vol.  XIV,  of  Tilloch's  Phil.  Mag.  Lond.  and  in  Vol. 
XLV,  of  the  Ann.  de  China.  Paris. 

t  See  Am.  Jour.  Vol.  I,  p.  98,  and  Vol.  II,  p.  181. 

t  Being  an  independent  original  witness  to  the  early  use,  (in  1802,)  of  this  fine  in- 
strument by  its  inventor;  and  having  been  in  the  habit  of  using  it  frequently,  for 
several  years  before  Dr.  Clarke's  experiments  were  published,  as  well  as  ever  since ; 
I  embrace  this  opportunity  to  say,  that  no  other  name,  than  that  of  Dr.  HARE,  can  be, 
in  my  view,  rightfully  associated  with  the  invention  of  the  Compound  Blowpipe. 


COMPOUND  BLOWPIPE. 


225 


5.  The  apparatus  which  I  employ,  is 
that  represented  in  the  annexed  figure, 
the  parts  of  which  are  described  at  page 
184  ;  it  is  convenient  and  effectual,  and 
has,  for  many  years,  enabled  me  to  per- 
form all  these  interesting  experiments 
with  great  facility,  and  on  a  large  scale. 
By  adverting  to  the  strictures  of  Dr. 
Hare,*  and  to  the  statement  of  the  edi- 
tors of  the  Annales  de  Chimie  et  de 
Physique, f  it  will  be  apparent,  that  in 
point  of  effect,  no  advantage  is  gained 
by  mingling  the  gases,  previously  to 
their  combustion, f  and  a  serious  danger 
is  necessarily  encountered,  notwithstanding  the  wire  gauze,  and  oil, 
and  mercury  valves  that  have  been  interposed  in  the  apparatus  of 
Newman  or  Brooke,  whose  figure  is  annexed. § 


\ 


It  is  a  small  copper  box,  (here  represented  on  the  left  of  the  page,) 

*  Am.  Jour.  Vol.  II,  p.  281.  t  Ibid,  Vol.  Ill,  p.  87. 

t  In  the  apparatus  which  1  employ,  stout  tubes  of  cast  silver  are  screwed  into  a 
piece  of  platinum,  shaped  like  the  lower  frustrum  of  a  pyramid,  and  this  is  the 
part  of  the  instrument  where  the  gases  issue ;  but  common  brass  tubes  hard  soldered 
and  screwed  into  a  silver  frustrum,  will  answer;  care  must  however  be  used,  that 
the  silver  is  not  melted,  which  it  certainly  will  be,  if  allowed  to  sink  into  the  hole 
burned  into  a  charcoal  support,  on  which  any  thing  is  melting  or  burning. 

§  Professor  Griscom  was  so  good  as  to  bring  this  instrument  to  Yale  College,  some 
years  since,  and  we  made  a  series  of  experiments  with  it,  but  with  no  results  differ- 
ent from  those  produced  by  Dr.  Hare's  blowpipe.  In  point  of  pressure,  we  carried 
it  so  far  that  the  copper  parallelepiped,  was  swollen  (ill  its  sides  were  convex,  but  no 
advantage  appeared  to  be  gained  bv  great  pressure. 

29 


226  COMPOUND  BLOWPIPE. 

furnished  with  an  injecting  syringe,  for  the  introduction  of  the  gases, 
previously  mingled  in  the  proportions  to  form  water ;  it  is  furnished 
also  with  an  internal  valvular  apparatus  of  wire  gauze,  to  guard  against 
explosions,*  and  with  a  tube  of  efflux  mounted  with  a  stop  cock  and  a 
platinum  orifice.  Great  pressure  may  be  a  convenient  means  of  bring- 
ing more  of  the  gases  into  the  reservoir,  but  it  is  of  no  avail  as  regards 
the  heat,  for  not  being  at  their  efflux,  adequately  resisted  by  the  air,  it 
amounts  to  nothing  more  than  supplying  the  gases  in  sufficient  quan- 
tity. The  previous  accurate  adjustment  of  the  proportions,  may  at 
first  view  seem  to  be  a  point  of  importance,  but  after  a  little  experi- 
ence, there  is  no  practical  difficulty  in  hitting  this  proportion,  when 
the  gases  come  from  different  reservoirs ;  the  eye  will  easily  perceive, 
by  the  color  and  size  of  the  flame,  and  the  appearance  of  the  focal 
point,  when  the  proper  proportion  is  attained  ;  and  the  effects  have 
proved  that  there  is  no  important  difference  in  the  power  of  the  in- 
struments. Mr.  Brooke's  blowpipe  has  the  advantage  in  neatness  and 
convenience  of  size,  but  its  contents  being  soon  exhausted  must  be 
frequently  renewed.  It  is  obvious  that  the  security  of  Dr.  Hare's 
contrivance  may  be  easily  connected  with  that  of  Mr.  Brooke,  by 
simply  providing  two  condensing  boxes  of  proper  size,  one  for  hy- 
drogen and  the  other  for  oxygen,  and  connecting  them  in  the  manner 
represented  in  the  cut  on  page  225.  On  account,  both  of  strength 
and  capacity,  two  globes  of  metal  would  be  most  convenient ;  and 
an  instrument,  like  that  in  the  figure  above  referred  to,  would  unite 
all  the  most  important  advantages  of  the  different  varieties  of  appara- 
tus, hitherto  constructed  for  this  purpose,  and  be  at  the  same  time, 
free  from  their  inconveniences,  and  from  the  danger  attending  Mr. 
Brooke's. 

6.  The  figure  in  the  note  below  represents  the  form  of  the  instru- 
ment, at  present,  used  by  Dr.  Hare.  It  is  less  simple  than  those  that 
have  been  described,  but  the  inventor  says,  that  he  has  found  it 
equally  convenient  in  use,  as  the  most  simple  form,  "  while  its  parts 
are  peculiarly  susceptible  of  advantageous  adjustment."! 


*  On  a  principle  which  will  be  illustrated  under  the  history  of  the  safety  lamp,  in 
the  section  on  the  carburetted  hydrogen  gases. 

t  '*  B  is  a  brass  ball,  with  a  vertical  perforation,  terminating  in  a  male  screw  above, 
and  in  a  female  screw  below.  Another  perforation,  at  right  angles  to  this,  causes 
a  communication  with  the  tube,  t,  which  enters  the  ball  at  right  angles.  A  simi- 
lar, but  smaller  brass  ball,  may  be  observed  above,  with  perforations  similar  to  those 
in  the  larger  ball,  and  a  tube,  in  like  manner,  entering  it  laterally.  This  ball  ter- 
minates in  a  male  screw  below,  as  well  as  above.  The  thread  of  the  lower  screw  is 
curved  to  the  left,  while  that  of  the  screw  of  the  larger  ball,  which  enters  the  same 
nut,  n,  is  curved  to  (he  right.  Hence  the  same  motion  causes  the  male  screws  to  ap- 
proach, or  recede  from  each  olher,  and  thus  determines  the  degree  of  compression 
given  to  a  cork  which  is  placed  between  them,  in  the  nut.  At  S, -above  the  ball,  a 
small  screw  may  be  observed,  with  a  milled  head.  This  is  connected  with  a  small 
tube  which  passes  through  the  cork  in  the  nut,  and  reaches  nearly  to  the  external 
orifice,  o,  from  which  the  flame  is  represented  as  proceeding.  This  tube  is  for  the 


COMPOUND  BLOWPIPE.  227 

Effects  of  the  compound  blowpipe. 

1.  Every  variety  of  mineral  matter  has  been  melted  by  it,  except 
the  diamond ;  it  is  evident  that  this  substance  and  charcoal  are  ex- 
ceptions, merely  on  account  of  their  combustibility. 

2.  All  combustible  bodies  burn  in  the  focus,  not  excepting  any  of 
the  metals :  the  latter  exhibit  beautiful  phenomena,  depending  on  the 
color  of  their  oxides  and  of  the  flame :  platinum,  because  it  is  too  fixed 
a  substance  to  form  vapor,  burns,  not  with  flame  but  with  scintillation. 

3.  Peculiar  facilities  are  afforded  by  having  two  separate  reser- 
voirs for  the  gases. 

(«.)  We  use  the  hydrogen  flame  alone  if  we  wish  a  lower  degree 
of  heat. 


most  part  of  brass,  but  at  its  lower  end  terminates  in  a  tube  of  platina.  It  communi- 
cates by  lateral  apertures  with  the  cavity  of  the  upper  ball,  but  is  prevented  by  the 
cork,  from  communicating  with  the  cavity  in  the  other  ball.  Hence  it  receives  any 
gas  which  may  be  delivered  into  the  upper  ball  from  the  lateral  pipe  which  enters 
that  ball,  but  receives  none  of  the  gas  which  may  enter  the  lower  ball,  B." 

"  Into  the  female  screw  of  the  latter,  a  perforated  cylinder  of  brass,  c,  with  a  cor- 
responding male  screw,  is  fitted.  The  perforation  in  this  cylinder,  forms  a  continu- 
ation of  that  in  the  ball,  but  narrows  below,  and  ends  in  a  small  hollow  cylinder  of 
platina,  which  forms  the  external  orifice  of  the  blowpipe,  0." 

"  The  screws,  s  s  s  s,  are  to  keep,  in  the  axis  of  the  larger  ball,  the  tube  which 
passes  through  it,  from  the  cavity  of  the  smaller  ball.  The  intermediate  nut,  by 
compressing,  about  the  tube,  the  cork  which  surrounds  it,  prevents  any  communf- 
cation  between  the  cavities  in  the  two  balls.  By  the  screw,  s,  in  the  vertex,  the 
orifice  of  the  central  tube  may  be  adjusted  to  a  proper  distance  from  the  external 
orifice. — Three  different  cylinders,  and  as  -many  central  tubes,  with  platina  orifices 
of  different  calibres,  were  provided,  so  that  the  flame  might  be  varied  in  size,  agree- 
ably to  the  object  in  view." 

S 


G 


228  ALKALIES. 

(b.)  We  let  in  a  portion  of  oxygen,  more  or  less,  as  we  wish  the 
heat  to  be  increased  to  any  degree,  till  we  reach  the  maximum. 

(c.)  We  ignite  charcoal  by  the  compound  flame,  and  then  shut 
off  the  hydrogen,  if  we  wish  to  have  the  effects  of  oxygen  gas  alone. 

(d.)  This  is  beautifully  seen  in  burning  the  metals ;  we  first  raise 
the  heat  by  the  compound  flame,  and  when  the  globule  of  metal  is 
heated  very  intensely,  we  cut  off  the  hydrogen  and  permit  the  oxy- 
gen alone  to  flow,  which  at  that  high  temperature  sustains,  and  even 
increases  the  combustion  of  the  metals,  not  excepting  cobalt,  nickel, 
silver  and  gold. 

4.  Most  intense  light  is  exhibited,  by  bringing  incombustible  bodies, 
such  as  the  earths,  and  particularly  lime  and  argil,  in  the  form  of  a 
pipe's  stem,  or  of  porcelain,  into  the  focus :  the  naked  eye  cannot 
endure  the  light :  and  in  this  focus  the  most  refractory  substances, 
the  rocks,  the  pure  earths  and  the  gems,  are  melted ;  the  diamond 
alone  excepted,  which  burns  with  great  intensity,  and  is  soon  exhaled 
in  the  form  of  carbonic  acid  gas.* 

THE  ALKALIES. 

Preliminary  Remarks. 

Several  eminent  writers  at  the  present  time,  have  broken  up  the 
long  established  class  of  alkalies,  and  distributed  them  according  to 
relations  derived  from  their  composition :  ammonia  is  described  in 
connexion  with  hydrogen  and  nitrogen,  and  potassa,  soda  and  lithia, 
under  the  metals.  Similar  remarks  are  applicable  also  to  the  earths. 
This  course  is  logical,  but  it  is  highly  inconvenient;  for  it  is  scarcely 
possible  to  take  more  than  a  few  steps  in  the  chemistry  of  particular 
bodies,  without  calling  in  the  aid  of  the  alkalies,  in  our  experiments 


*  For  the  details  of  these  and  of  numerous  other  experiments,  see  Dr.  Hare's  ori- 
ginal pamphlet,  and  his  and  my  own  various  memoirs  in  the  Phil.  Trans,  of  Phila- 
delphia; in  Tilloch's  Phil.  Mag. ;  in  the  Annales  de  Chimie  el  de  Physique ;  in  Dr. 
Bruce's  Journal,  and  in  the  American  Journal. 

Dr.  Hare  remarks,  (Comp.  p.  77,)  that  excepting  the  republication  of  his  memoir 
in  Tilloch's  Phil.  Mag.  and  in  the  Ann.  de  Chim.  et  de  Phys.  and  a  quotation  of  his 
results  in  Murray's  System  of  Chemistry,  they  had  been  generally  neglected. 
"Hence,  (adds  Dr.  Hare,)  a  modification  of  the  hydro-oxygen  blowpipe  was  con- 
trived by  Mr.  Brooke.  Dr.  Clarke,  by  means  of  this  modification,  repeated  my  ex- 
periments and  those  of  Prof.  Silliman,  without  any  other  notice  of  our  pretensions 
than  such  as  was  calculated  to  convey  erroneous  impressions." 

I  regret  to  say  that  this  omission,  although  made  known,  was  never  corrected,  and* 
that  the  experiments  of  Dr.  Clarke,  most  of  which  had  been,  years  before,  performed 
and  accounts  of  them  published  by  Dr.  Hare  or  myself,  were  entitled  to  no  credit 
for  originality ;  while  the  almost  identity  (in  many  cases)  of  the  language  in  which 
they  were  described,  with  that  used  by  us  so  long  before,  proves  that  the  results 
with  the  two  instruments  were  the  same. 

It  is  not  pleasant  to  transgress  the  kind  maxim,  nil  de  mortuis  nisi  bonum;  but 
truth  obliges  me  in  this  instance  to  do  it. 

The  claims  of  Dr.  Clarke  respecting  the  compound  blowpipe  were  entirely  un- 
founded. 


ALKALIES.  229 

and  reasoning :  this  remark  is  perhaps  equally  true  of  the  principal 
acids,  and  both  these  important  classes  of  bodies  should  be  placed  as 
early  as  possible  in  the  hands  of  the  student.  It  has  been  already 
stated,  in  the  plan  of  the  work,  that  in  teaching,  I  have  found  the 
most  convenience  in  introducing  the  alkalies  before  the  acids ;  al- 
though my  preference  is  not  so  decided  that  I  should  have  any  seri- 
ous objection  to  the  opposite  course.  But,  I  am  not  willing  to  post- 
pone the  history  of  the  alkalies  and  earths  until  we  come  to  that  of 
the  metals,  and  to  treat  of  them  merely  as  appendages  of  those  bodies ; 
and  I  should  be  still  more  reluctant,  for  the  sake  of  avoiding  this  diffi- 
culty, to  bring  in  the  metals  first,  or  in  connexion  with  the  simple 
combustibles,  as  some  authors  have  done ;  nor  is  it  a  sufficient  reason, 
that  the  alkalies*  and  earths  then  fall  in  naturally  as  metallic  oxides. 
It  is  true  that  modern  discovery  has  increased  the  difficulty  of  giving 
a  strictly  logical  definition  of  an  alkali ;  but  the  bodies  that  have  usu- 
ally been  called  by  this  name  are,  in  some  of  their  forms,  familiarly 
known  ;  they  have  also  a  sufficient  number  of  properties  in  common, 
to  distinguish  them  from  other  classes  of  bodies,f  and  this  is  the  most 
important  point  to  be  attained  in  our  arrangements.  It  is  true  also 
that  their  properties  graduate  into  those  of  some  of  the  earths;  but 
it  is  sufficient  to  designate  the  latter  as  alkaline  earths,  and  to  leave 
the  remainder  of  them  to  be  called  earths  proper. 

Explanatory  Statement. 

The  alkalies,  when  they  are  to  be  prepared  pure  for  chemical  pur- 
poses, are  generally  extracted  from  their  saline  combinations,  and  it 
is  therefore  necessary  to  premise,  that  a  salt  is  composed  of  an  acid 
and  a  base :  the  alkaline  salts  have,  of  course,  an  alkaline  base,  and 
the  object  of  our  processes  is  to  separate  the  acid,  and  leave  the  base 
isolated,  and  free  also  from  accidental  bodies,  commonly  called  im- 
purities. 

In  giving  the  history  of  potassa,  soda  and  ammonia,  only  two  acids 
need  be  mentioned  :  potassa  and  soda,  as  they  occur  in  commerce, 
are  usually  found  combined  with  the  carbonic  acid ;  and  ammonia 
both  with  that  and  with  the  muriatic  acid.  The  carbonic  acid,  com- 
posed of  carbon  and  oxygen,  is  a  gaseous  body,  which  when  com- 
bined with  the  alkalies,  blunts  their  properties,  but  it  is  easily  remov- 
ed from  these  combinations,  partially  by  heat  and  completely  by  the 
superior  affinity  of  lime.  It  is  also  entirely  expelled  by  stronger 
acids,  but  a  new  salt  is,  in  that  case,  formed ;  and  in  general  the  form- 
ing of  such  a  compound,  would  rather  retard  than  advance  our  pro- 


*  Ammonia  excepted,  which  no  one  arranges  under  the  metals. 
i  It  is  scarcely  necessary  to  add,  that  I  do  not  include  the  new  alkaline  vegetable 
proximate  principles,  morphia,  delphia,  quinia,  strychnia,  &c. 


230  ALKALIES. 

gress  towards  obtaining  the  pure  alkali.  The  muriatic  acid  is  also  a 
gaseous  body :  it  cannot  be  expelled  from  the  alkalies  by  heat :  it  can 
be  displaced  by  the  sulphuric  acid,  but  that  will  only  engage  the  alkali 
in  a  new  combination :  to  remove  it  entirely,  we  employ  lime  in  this 
case  also,  which  will  attract  it  away  and  leave  the  alkali  free  and  pure.* 

AMMONIA POTASSA SODA — LITHIA. 

GENERAL    CHARACTER    OF    ALKALIES. 

!a.}  Caustic  to  the  animal  organs. 
6.)  Volatilizable  by  heat,  but,  except  ammonia,  not  decomposable 
by  heat  alone. 

(c.)  Combine  with  acids  and  form  salts  $f  acids  and  alkalies  are 
antagonists. 

(d.)  Very  soluble  in  water,  even  in  the  state  of  carbonate ;  solu- 
ble also  in  alcohol. 

(e.)  Turnf  most  blue,  purple,  and  other  dark  vegetable  colors,  to 
green  ;  as  tincture  or  infusion  of  violets,  and  of  purple  cabbage. 

(f.)  Turn  most  yellow  vegetable  colors  to  brown ;  as  turmeric  and 
rhubarb  ;  and  red  to  purple,  as  tincture  of  brazil  wood.§ 

(g.)  The  colors  altered  by  an  alkali,  are  generally  restored  by  a 
due  proportion  of  an  acid. 

(h.)  Unite  with  oils  and  form  soaps  ;  corrode  woollen  cloth  ;  and 
are  generally  powerful  solvents  of  animal  matter. 

(i.)  Taste,  acrid  and  peculiar;  particularly  different  from  that  pro- 
duced by  acids ;  it  is  called  the  alkaline  taste,  and  in  a  milder  form, 
is  observed  in  pearl  ashes  and  soda. 

SEC.  I. — AMMONIA. || 

Remark. — This  alkali  is  placed  first  because  of  its  relation  to  ni- 
trogen, and  hydrogen,  which  have  been  described. 

*  Had  we  begun  with  acids,  an  explanatory  statement  would  have  been  necessary 
respecting  alkalies  and  salts,  as  two  of  the  most  important  of  the  acids,  the  nitric  and 
muriatic,  are  extracted  from  saline  combinations. 

t  The  definition  of  alkali  proposed  by  Dr.  Ure,  founded  on  the  power  of  "  com- 
bining with  acids,  so  as  to  neutralize  or  impair  their  activity,"  would  confound  them 
with  the  earths  and  metallic  oxides. 

t  The  power  to  affect  vegetable  colors,  continues  even  after  combination  with 
carbonic  acid,  which  distinguishes  the  alkaline  from  the  earthy  carbonates.  Ammo- 
nia being  a  volatile  alkali,  sometimes  escapes  by  evaporation,  and  the  original  color 
is  thus  restored. 

§  Bibulous  paper,  wet  with  these  colored  solutions,  forms  test  papers,  by  which 
the  application  of  colors  is  easily  made.  Litmus  is  not  changed  by  alkalies,  but  if 
previously  reddened,  it  is  turned  back  by  an  alkali  to  its  original  color,  and  thus  be- 
comes a  test. 

||  Called  also  the  volatile  alkali.  Popular  name  hartshorn,  because  it  was  an- 
ciently distilled  from  the  horns  of  the  hart  or  deer,  which,  in  common  with  other 
animal  matter  contain  its  elements. 


ALKALIES. 


231 


1.  THE  NAME  is  derived  from  that  of  sal  ammoniac,  or  the  mu- 
riate of  ammonia,  and  this  from  the  sandy  country  of  Lybia,*  (a^orf,) 
where  the  salt  was  first  procured. 

2.  DISCOVERY. — The  gas  was  discovered  by  Dr.  Priestley,  by 
heating  the  aqueous  solution  of  the  shops ;  he  collected  the  gas  in 
vials  filled  with  mercury,  which  was  expelled  by  the  gas. 

Process  for  obtaining  gaseous  Ammonia. 

3.  PREPARATION. 

(a.)  From  equalparts 
of  powdered   muriate 
of  ammonia,  and  dry- 
slacked-\  quick  lime, in- 
timately mingled,  and 
heated  moderately  in 
a    glass   retort ;{    we 
receive  the   gas  over 
mercury,  as  in  the  an- 
nexed cut  of  Dr.  Hare. 
It  is  very  convenient 
to  displace  the  com- 
mon air,  by  conveying 
the  gas,  by  a  glass  tube 
into  an  inverted  glass 
vessel  5  as  in  the  annexed  figure,  where  a  is  the  flask  containing  the 
materials ;  b  a  spirit  lamp,  for  heat ;  c  the  recipient, 
and  d  the  connecting  tube.     It  is  obvious  that  this  pro- 
cess is  founded  on  the  levity  of  the  gas,  which  displaces 
the  air  of  the  vessel. 

(b.)  Heat  the  aqueous  solution  of  ammonia  to  expel 
the  gas ;  but  this  is  not  an  eligible  mode,  as  the  water  dis- 
tils over,  is  condensed  above  the  mercury,  and  reab- 


sorbs  the  gas.  In  the  process  3,  (b.)  we  know  when 
the  recipient  is  full,  both  by  the  pungent  smell,  and  by 
bringing  a  feather  dipped  in  muriatic  acid  near  the  mouth 
of  the  vessel,  when,  if  the  gas  is  overflowing,  there  will 
be  a  white  cloud  of  regenerated  muriate  o 


fgrjL 

ammonia.     When  it  is 

important  to  have  the  gas  very  dry,  unslacked  lime  should  be  used ; 
but  it  is  apt  to  adhere  to  the  glass  and  break  it. 
4.  PHYSICAL  PROPERTIES. 


*  Called  Ammonia.  Some  say  in  allusion  to  the  sand ;  others  to  the  temple  of 
Jupiter  Ammon. 

t  That  is,  slacked  with  such  a  portion  of  water,  as  to  remain  dry. 

.£  In  all  operations  for  collecting  gases  over  mercury,  ground,  tubulated  glass  re- 
torts are  better  than  flasks,  as,  from  the  pressure,  the  latter  are  apt  to  leak  at  the  cork, 


ALKALIES. 

(a.)  Transparent  and  colorless ;  smell,  highly  odorant  and  pun- 
gent.— Agreeable,  if  largely  diluted  with  air  ;  it  causes  a  sharp  prick- 
ly sensation  in  the  hands,  and  if  the  skin  is  moist,  it  is  absorbed,  and 
is  almost  corrosive  ;  combining  with  the  moisture  on  the  eye-balls,  it 
causes  a  sensation  of  intolerable  pain.  It  is  therefore  decidedly  caus- 
tic, and  could  it  be  made  solid  without  combination,  it  would  doubtless 
act  on  animal  matter  with  as  much  energy  as  the  fixed  alkalies  do. 

(6.)  Specific  Gravity  0.5957,  air  being  I.— -Weight,  18.17,  at 
the  medium  temperature  and  pressure. 

(c.)  Hostile  to  animal  life. — An  animal  immersed  in  it  instantly 
dies.  It  kills  by  suffocation  and  excoriation  ;  admitted  into  the  fauces 
it  is  intensely  painful ;  it  causes  a  violent  spasm  as  soon  as  it  reaches 
the  glottis,  and  produces  the  most  distressing  coughing,  and  a  lasting 
irritation. 

5.  CHEMICAL  PROPERTIES. 

(a.)  Instantly  absorbed  by  water,  a  drop  of  which  being  admitted 
and  agitated  with  the  gas,  the  mouth  of  the  vessel  being  closed  by  the 
finger,  and  then  opened  under  the  fluid,  it  rushes  in  as  it  would  into  a 
vacuum.  Ice  melts  in  the  gas  more  rapidly  than  it  would  in  the  fire ;  if 
passed  up  into  ajar  of  gas  standing  over  mercury,  the  metal  rises  rap- 
idly as  the  ice  melts,  and  the  gas  is  absorbed  to  form  liquid  ammonia. 

(b.)  Ice-cold  water  absorbs  780  times  its  volume  of  this  gas. — 
(Thomson.)  Sir  H.  Davy  has  stated  its  absorbability  at  475  ;  water 
easily  absorbs  this  quantity,  and  then  holds  about  one  third  of  its 
weight  of  the  gas.  Sir  H.  Davy's  more  recent  statement  was,  that 
670  times  its  volume  of  this  gas,  was  condensed  into  one  of  water. 

(c.)  Aqua  jlmjnonice  is 
prepared  in  pharmacy  and  in 
chemistry,  by  passing  am- 
moniacal  gas,  from  equal 
parts  of  slacked  lime,  and 
muriate  of  ammonia,  heated 
in  an  iron  bottle,  through  ice 
cold  water,  contained  in 
Woulfe's  bottles,  the  contents 
of  the  first  being  rejected  as 
impure.  For  a  figure  of 
Woulfe's  apparatus,  see  mu- 
riatic acid.  I  annex  a  cut 
from  Dr.  Hare,  of  an  appa- 
ratus which  will  answer  for 
a  common  experiment.  It 
needs  no  explanation. 

(d.)  The  aqua  ammonia 
smells  like  the  gas;  it  is  a 
very  useful  reagent,  and  an 
efficacious  medicine. 


ALKALIES,  233 

The  more  highly  water  is  impregnated  with  ammonia,  the  lighter 
it  is,*  as  appears  from  the  following  table  of  Sir  H.  Davy,  in  which 
the  proportions  are  by  weight. 

Sp.  gr.                                      Ammonia.  Water. 

0.8750                                 32.50  67.50 

0.8875  -                   -      29.25  -                  -      70.75 

0.9000                                 26.00  74.00 

0.9054  -                   -      25.37  -                  -      74.63 

0.9166                                22.67  77.93 

0.9255  -                   -      19.54  -                  -      80.46 

0.9326                                 17.52  82.48 

0.9385  -                   -      15.88  -                  -      84.12 

0.9435                                 14.53  -  85.47 

0.9476                                 13.46  -  -      86.54 

9.9513                                 12.40  87.60 

0.9545  -                   -       11.56  -      88.44 

0.9573                                 10.82  89.18 

0.9597                          -      10.17  -  -      89.83 

0.9619                                   9.60  90.40 

0.9692  -                            9.50  -                   -      90.50 

Dr.  Uref  has  given  another  table  ;  he  thinks  the  numbers  in  Sir  H. 
Davy's  too  high  by  about  1  per  cent.  A  vial  containing  224  grains 
of  distilled  water,  will  contain  only  216  grains  of  strong  aqua  am- 
moniae. 

(e.)  Alcohol  can  be  impregnated  in  the  same  manner,  and  it  may 
be  done  at  the  same  time,  in  a  separate  bottle  of  the  apparatus. 

(/.)  Jlmmoniacal  gas  extinguishes  flame,  but  burns  slightly  ;  very 
evidently,  if  taken  in  quantities  not  less  than  a  pint,  and  having  at 
the  same  time  access  to  the  air,  when  it  burns  as  it  rises,  with  a 
a  voluminous  yellow  flameff  If  it  were  collected  in  large  jars,  in 
the  manner  already  described,  3.  (a.),  it  would  doubtless  burn  with 
a  flame  still  more  conspicuous. 

(g.)  If  introduced  into  oxygen  gas,  in  the  form  of  a  jet,  it 
burns,  and  the  products  are  water  and  nitrogen  gas  ;  the  hydrogen 
uniting  with  the  oxygen,  and  leaving  the  nitrogen  behind. 

6.  ANALYSIS,  COMPOSITION,  AND  PROPORTION  OF  ELEMENTS. 

(a.)  By  the  electric  spark,  passed  through  the  gas,  standing  in  a 
detonating  tube,  over  mercury.  It  requires  two  or  three  hundred 
discharges  to  effect  the  decomposition. 


*  The  same  fact  is  observed  in  the  solutions  of  its  salts.        t  Diet.  24  Ed.  p.  142. 
t  Am.  Jour.  Vol.  VI,  p.  185. 


234  ALKALIES. 

(b.)  By  furnace  heat,  the  gas  being  driven  through  a  porcelain  tube ; 
but  the  decomposition,  is  in  this  way  very  tardy,  and  requires  an  in- 
tense heat  to  produce  a  few  bubbles  of  gas.*  It  is  much  better  done 
in  an  iron  tube,  filled  with  coils  of  iron  wire,  or  copper,  silver,  gold, 
or  platinum;  their  relative  energy  corresponds  with  the  order  in 
which  they  are  named  above,  but  iron  is  by  far  the  most  power- 
ful. The  explanation  of  this  decomposition,  appears,  at  first,  not 
very  easy  ;  since  the  metals  do  not  combine  with  either  of  the  con- 
stituents of  ammonia,  and  are  not  altered.  Probably  they  act  by 
transmitting  heat ;  the  metals  neither  gain  nor  lose  in  weight,  and 
appear  to  act  as  conductors  only.  The  result  of  the  experiment 
gives  3  volumes  of  hydrogen  and  1  of  nitrogen  gas,  in  mixture  ; 
electrization  gives  the  same  result  ;  by  weight,  17.64  hydrogen, 
82.35  nitrogen  ;  as  the  gases  are  condensed  into  half  their  volume,  the 
specific  gravity  of  ammonia  is  not  that  of  nitrogen,  .9782  +  3  hydro- 
gen .2083=1.1865,  but  half  of  this  =.593.f 

A  soft,  pasty,  semi  crystallized  mass  is  obtained,  when  a  globule 
of  mercury  is  galvanized,  or  a  piece  of  potassium  laid,  in  a  cavity, 
in  a  solid  ammoniacal  salt,  particularly  in  muriate  of  ammonia; 
it  resembles  an  amalgam,  and  hence  it  has  been  supposed  that  either 
hydrogen  or  nitrogen,  or  both,  has  a  metallic  base ;  but  the  sub- 
stance has  never  been  obtained  isolated,  and  no  satisfactory  conclu- 
sion can  be  built  upon  it, 

(c.)  By  oxygen. — 100  measures  of  ammonia  +50  of  oxygen, 
being  detonated  over  mercury  in  a  tube,  the  oxygen  disappears  ; 
then  add  30  or  35  measures  more  of  oxygen ;  detonate  again ;  one 
third  of  the  entire  diminution  is  oxygen,  and  double  this  is  the  hydro- 
gen ;  the  nitrogen  remains,  deducting  any  that  may  have  been  intro- 
duced with  the  oxygen  gas ;  this  result  corresponds  with  that  under 
(b.)  giving  3  volumes  of  hydrogen,  and  1  of  nitrogen,  which,  as  they 
exist  in  a  state  of  combination  in  ammonia,  are  condensed  into  2  vol- 
umes ;  the  decomposition  of  ammonia,  therefore,  doubles  its  volume  ; 
it  is,  however,  no  longer  ammonia,  but  a  mixture  of  its  constituent 
gases,  hydrogen  and  nitrogen. 

(d.)  The  mixed  hydrogen  and  nitrogen  gases,  obtained  by  igne- 
ous or  electrical  decomposition,  may  be  analyzed  in  the  same  man- 
ner, by  detonation  with  oxygen,  and  will  give  the  same  result.} 


*  As  the  ammonia  is  instantly  absorbed  by  water,  none  of  it  will  pass  through  that 
fluid,  and  the  mixed  gases  obtained,  are  of  course  hydrogen  and  nitrogen.  I  have  re- 
peatedly carried  this  experiment,  by  the  aid  of  bellows,  almost  to  the  fusion  of  the 
porcelain  tube,  without  obtaining  a  cubic  inch  of  gas;  while  if  there  be  iron  in  the 
tube,  the  gases  come  over,  abundantly. 

t  .595  is  the  number  which  we  have  quoted,  p.  232 ;  Dr.  Thomson  states  it  at  .590. 

\  The  analysis  by  chlorine  is  very  elegant  and  easy.  See  that  topic.  The  chlo- 
rine removes  the  hydrogen,  and  leaves  the  nitrogen. 


ALKALIES.  235 

7.  SYNTHESIS. 

(a.)  Hydrogen  gas  and  nitrogen  gas,  mingled  in  the  proper  pro- 
portions, do  not  form  ammonia,  nor  would  they  ever  do  it — their  spe- 
cific caloric  opposes  the  union ;  they  would  remain  always  a  mere 
mixture. 

(6.)  Hydrogen  in  its  nascent  state,  meeting  with  nitrogen,  forms 
ammonia  ;  this  happens  when  hydrogen  is  disengaged  from  moistened 
iron  filings,  included  in  a  jar  of  nitrogen. 

(c.)  Nitric  acid,  acting  on  tin  or  on  phosphorus,  forms  ammonia  ; 
water  furnishing  the  hydrogen  and  the  acid  the  nitrogen ;  it  is  then 
disengaged  by  a  little  lime  which  arrests  the  acid,  and  the  ammonia 
is  perceived  by  its  odor,  and  by  a  white  fume  with  muriatic  acid.* 

(d.)  Ammonia  is  formed  during  animal  decomposition ;  both  its 
elements  being  evolved  from  the  animal  matter,  and  uniting  at  the 
instant ;  this  is  the  origin  of  ammonia  in  stables,  privies,  and  other 
similar  places. 

8.  ACTION  ON  COLORS. f 

(a.)  Red  tincture  of  alkanet  becomes  blue ; {  blue  infusion  of  cab- 
bage, green ;  diluted  yellow  tincture  of  rhubarb  or  turmeric,  brown. 


*  Ann.  de  Chim.  et  de  Physique,  XXIV.  295. 

t  I  am  not  aware  that  any  reason  has  been  suggested  for  these  changes  of  color ; 
certainly  none  has  occurred  to  me  that  is  satisfactory.  As  a  general  fact,  permanent 
changes  of  color  depend  on  changes  of  composition,  as  is  evinced  in  innumerable 
cases ;  for  instance,  red  lead  and  red  precipitate  contain  oxygen,  a  colorless  body, 
and  metals,  one  of  which  is  white  and  the  other  gray;  indigo  is  intensely  blue, 
but  becomes  green  by  losing  oxygen.  In  the  case  of  the  test  colors,  the  color  is 
permanent,  as  long  as  the  coloring  matter  is  not  decomposed,  which  happens  event- 
ually, and  perhaps  we  may  say  that  a  peculiar  combination  takes  place  between  the 
coloring  matter  and  the  acid  or  alkali,  although  we  can  give  no  reason,  any  more  thaa 
in  other  cases,  why  these  particular  colors  should  result,  or  why  there  should  be  any 
change  of  color. 

The  autumnal  hues  of  the  leaves  of  trees  probably  depend  on  similar  causes ;  that 
is  to  say,  on  the  fuller  developement  of  acid  or  alkali,  by  the  variations  of  temperature  ; 
for  these  agents  always  exist  abundantly  in  vegetable  bodies,  and  particularly  in  their 
fluids.  It  is  not  impossible  that  galvanic  principles,  may  aid  in  producing  and  mod- 
ifying the  effects. 

If  any  person  would  examine  the  leaves  of  the  sugar  maple,  for  instance,  just  be- 
fore the  first  autumnal  frosts,  and  while  they  are  still  green,  he  could  easily  decide 
whether  acid  or  alkali  were  predominant,  or  whether  either  was  to  be  found  in  a 
state  of  freedom  ;  then  let  him  examine  the  leaves  after  they  have  turned  red,  a  color 
which  we  should  of  course  attribute  to  the  developement  of  acid.  A  similar  exa- 
mination should  be  made  of  the  chemical  condition  of  leaves  exhibiting  other  col- 
ors produced  by  decay,  as  the  yellow  of  the  hickory,  the  brown  of  several  species  of 
oak.  &c.  and  so  of  the  different  colors  observed  in  leaves  of  the  same  trees  in  the  va- 
rious stages  of  decomposition. 

In  the  American  Journal,  Vol.  xvi,  p.  215,  there  is  a  reference  to  an  essay  on  this 
subject,  in  the  Ann.  de  Chim.  et  de  Phys.  Aout,  1828,  in  which  it  is  stated,  that  the 
colored  parts  of  vegetables,  appear  to  contain  a  particular  substance,  called  by  Prof. 
De  Candolle,  chromule,  and  the  autumnal  change  in  the  color  of  leaves  is  attributed 
to  the  fixation  of  oxygen,  and  to  a  sort  of  acidification  of  the  chromule. 

J  We  owe  this  very  convenient  test,  to  Dr.  Hare. 


236  ALKALIES. 

&c. ;  acids  bring  the  colors  back,  as  has  been  stated  in  giving  the 
general  characters. 

(b.)  In  applying  these  colors,  we  may  fill  a  small  tube  stopped  at 
one  end,  or  an  essence  vial,  with  the  colored  fluid,  and  with  a  finger 
on  the  mouth,  turn  it  upward  into  a  jar  of  the  gas  standing  over  mer- 
cury ;  instantly  the  color  will  change,  and  the  gas  be  absorbed. 

9.  CONDENSATION  OF  THE  GAS,  BY  COLD  AND  PRESSURE. 

This  was  accomplished  by  Mr.  Faraday,*  by  disengaging  it  in 
sealed  syphon  tubes,  from  chloride  f  of  silver  which  absorbs  it  in 
large  quantities,  100  grains  absorbing  130  cubic  inches  of  the 
gas.  The  leg  of  the  syphon  containing  the  chloride,  was  heated  to 
100°  Fahr.  and  the  other  leg  kept  cold  by  ice.  Ammoniacal  gas  was 
evolved,  and  part  of  it  was  by  the  pressure  of  the  rest,  reduced  to  the 
liquid  state.  It  was  a  colorless  fluid ;  its  refractive  power  was  great- 
er than  that  of  water,  and  at  50°,  its  pressure  equalled  6.5  atmos- 
pheres ;  its  specific  gravity  was  0.76,  water  being  1. 

10.  PROCESS  IN  THE  ARTS. 

By  the  distillation  of  bones,  and  other  firm  parts  of  animal  sub- 
stances, ammonia  is  generated,  by  the  reaction  of  its  elements,  but 
it  is  more  or  less  combined  with  carbonic  acid.  Among  the  ele- 
ments of  animal  matter,  we  always  find  hydrogen  and  nitrogen.  The 
ammonia  obtained  is  impure,  mixed  with  animal  oil,  &c.  and  is  pu- 
rified by  combining  it  with  the  muriatic  or  sulphuric  acid,  and  then 
decomposing  this  ammoniacal  salt  by  quick  lime,  in  the  manner  alrea- 
dy described.  In  the  manufactories,  bones  and  horns  are  commonly 
employed,  and  sometimes  the  refuse  of  the  slaughter  houses.  An 
iron  retort,  or  still  is  generally  used  ;  the  bones  are  introduced  rough- 
ly broken,  and  a  strong  heat  applied.  A  tar  like  substance,  oil,  and 
very  fetid  gases,  are  evoked,  which  should  always  be  burned  as 
they  are  both  noxious  and  disgusting.  Valves  are  sometimes  fixed 
in  the  apparatus  to  prevent  the  return  of  common  air ;  this  would  of 
course  happen  when  the  apparatus  grows  cold,  and  the  air  by  ming- 
ling with  the  inflammable  gases,  might  occasion  an  explosion,  when 
the  fire  is  lighted  again.  Animal  charcoal,  mixed  with  phosphate  of 
lime,  remains  in  the  iron  vessel.  J 

11.  PHARMACEUTICAL  PROCESS. 

To  procure  aqua  ammoniae,  we  may  employ  either  a  still§  or 
Woulfe's  bottles  ;  the  latter  are  always  used  in  philosophical  laborato- 
ries ;  the  proportions  of  the  materials  are  1  to  2  parts  of  slacked  lime, 
and  1  of  pulverized  sal  ammoniac,  and  the  gas  is  received  in  water, 


*  Phil.  Trans.  1823,  p.  196.  I  Muriate.  t  Gray's  Op.  Chem. 

§  In  the  large  way,  one  ofiron  is  used  with  a  stone-ware  head,  and  stone- ware  bot- 
tles may  be  used  for  the  condensation. 


ALKALIES,  237 

equal  in  weight  to  the  salt  employed  ;  it  is  kept  cold  by  ice  or  snow, 
or  at  least  by  cold  water  often  renewed.  When  the  gas  ceases,  the 
addition  of  a  little  water  to  the  materials  in  the  retort,  will  renew  the 
flow  of  gas,  and  produce  complete  decomposition  ;  ten  pounds  of  sal 
ammoniac  should  produce  thirty  pounds  of  aqua  ammonia?,  sp.  gr. 
.950,  and  containing  about  12  per  cent,  of  ammonia.*  The  Edin- 
burgh college  prepare  it  of  the  strength,  .989  ;  that  of  London,  .960. 
— Ure. 

12.  NATURAL  SOURCES. 

From  the  decomposition  of  animal  substances,  as  in  privies  and 
stables,f  &tc.  ;  it  is  probable  that  ammonia  is  produced  generally 
during  the  spontaneous  decomposition  of  animal  bodies ;  a  pungent, 
reviving,  and  antiseptic  gas  thus  springs  up,  from  the  very  bosom  of 
putrefaction. 

The  Chenopodium  vulvaria  emits  this  gas  in  the  act  of  vegetation, 
and  many  flowers,  even  those  with  an  agreeable  odor|  do  the  same. 

13.  GENERAL  INFERENCE. 

In  destructive  distillation,  and  in  spontaneous  decomposition,  the 
appearance  of  ammonia  indicates  nitrogen,  and  of  course  hydrogen. 

This  remark  will  apply  not  only  to  animal  substances,  but  to  plants, 
when  they  afford  ammonia,  as  all  those  do  which  putrefy  with  an  an- 
imal odor. 

14.  POLARITY. 

Ammonia  is  attracted  to  the  negative  pole  in  the  galvanic  circuit, 
and  is  therefore  electro-positive. 

15.  COMBINING  WEIGHT  17 — made  up  of  1  proportion  of  nitro- 
gen 14,  and  3  of  hydrogen  =17. 

16.  MEDICAL  AND  OTHER  USES. — These  are  important;  taken  in- 
ternally, in  the  proportion  of  8  or  10  drops  to  a  wine  glass  full  of  wa- 
ter, ammonia  is  a  powerful  and  valuable  stimulant,  producing  the  most 
useful  effect  of  alcohol,  but  without  its  mischiefs.     It  is  also  an  ant- 
acid. 

Externally,  it  is  a  rubefacient,  but  it  is  generally  used  in  the  form 
of  volatile  liniment,  made  by  agitating  aqua  ammonias  in  a  vial  with 
olive  oil.  Ammonia  is  a  very  valuable  antidote  to  poison.  Either 
the  aqua  ammoniae,  the  carbonate,  or  the  volatile  liniment  may  be 
used  externally,  and  the  two  former  internally.^ 

*  The  iron  bottles  in  which  quicksilver  is  brought,  answer  very  well  for  the  de- 
composition of  sal  ammoniac,  and  the  muriate  of  lime  is  easily  extracted  from  them 
by  hot  water. 

t  In  these  places,  the  ammonia  is  mixed  with  fetid  gases;  the  pungency  belongs 
to  the  former,  and  the  disagreeable  odor  to  the  latter.  The  ammonia  is  often  so 
abundant  as  to  produce  a  white  cloud,  when,  in  these  places,  the  stopper  is  withdrawn 
from  a  vial  of  muriatic  acid.  In  Europe,  ancient  hotels  are  sometimes  tilled  with 
ammoriiacal  exhalations,  arising  from  the  privies  within  the  premises. 

t  Jour,  de  Phar.  Feb.  1824,  p.  100 ;  also,  Am.  Jour.  Vol.  X,  p.  190. 

$  See  Am.  Jour.  Vol.  XVI,  p.  183. 


238  ALKALIES. 

It  is  given  to  animals,  to  relieve  the  inflation  occasioned  by  eating 
excessively  of  green  grass,  clover,  lucerne,  &c.  It  is  of  the  most  im- 
portant and  extensive  use  in  practical  chemistry. 

Remarks. 

Ammonia  is  one  of  those  gases  which  destroy  animal  life,  when 
it  is  mingled,  in  only  a  small  proportion,  with  the  air  that  is  respired. 

It  was  found  by  Chevallier  in  iron  rust,  in  situations  exposed  to 
animal  effluvia ;  it  was  formed  when  clean  iron  that  had  been  ignited 
was  boiled  in  pure  water,  and  it  appears  to  be  always  formed  when 
iron  decomposes  water  in  contact  with  air ;  the  water  affording  the 
hydrogen,  and  the  air  the  nitrogen. 

It  appears  also  to  exist  in  natural  iron  ores,  such  as  the  red  hema- 
tite of  Spain,  the  micaceous  ore,  and  the  Jenite  of  Elba.* 

It  has  already  been  mentioned  that  ammonia  is  formed  when  mois- 
tened iron  filings  are  placed  in  nitrogen  over  mercury,  as  ascertained 
by  Dr.  Austin,  in  1788. 

SEC.  II. — POTASSA. 

1.  NAME. 

From  the  potashes  of  commerce  ;  and  their  name  is  obviously 
derived  from  ashes,  and  the  pots  (called  potash  kettles,)  in  which  the 
lixivium  is  boiled  down.  Some  of  the  old  names  were,  vegetable 
alkali — salt  of  tartar — salt  of  wormwood,  and  alkali  of  nitre,  in  allu- 
sion to  the  principal  sources  from  which  the  alkali  is  obtained. 

2.  PROCESS  OF  THE  ARTS.f 

The  watery  lixivium  J  of  the  ashes§  mixed  with  quick  lime,  being 
boiled  down  in  the  iron  pots  or  kettles,  the  residuum  is  ignited,  and 
then  constitutes  the  potashes  of  commerce.  Placed  in  a  reverbera- 
tory  furnace,  and  stirred  while  the  flame  plays  upon  it,  it  becomes 
white,  and  is  then  the  pearlashes  of  commerce  ;  it  is  thus  purified  by 
fire  only,  by  the  destruction  of  extractive  and  other  combustible  mat- 
ter, and  the  dissipation  of  volatile  principles,  gases,  &c. ;  it  loses  gen- 
erally about  10  or  15  percent,  of  its  weight. || 

The  purest  alkali  is  obtained  from  the  mutual  action,  in  a  red  hot 
iron  pot,  of  nitre  1,  and  tartar  2  ;  the  basis  of  both  salts  being  potash, 


*  Am.  Jour.  Vol.  XIII,  p.  181. 

t  To  render  this  process  intelligible,  nothing  more  need  be  premised  than  that  be- 
sides impurities,  the  potash  of  commerce  is  found  combined  with  carbonic  acid, 
which  the  lime  detaches  by  its  superior  affinity,  and  thus  liberates  the  alkali. 

\  This  word  is  used  to  denote  a  lye  made  with  ashes,  and  is  derived  from  the 
Latin  word  lix,  denoting  this  preparation,  and  Lixa  is  a  worker  in  this  branch  of  the 
Arts. — Parkes. 

§  When  wood  is  burned,  the  ashes  constitute  about  l-200th  part  of  its  weight. — 
lire's  Diet. 

||  See  Dr.  Roger's  account  in  Am.  Jour,  Vol.  VIII,  p.  304. 


ALKALIES.  239 

and  the  acids  being  destroyed  by  their  action  on  each  other ;  also  by 
igniting  nitre  in  a  crucible  of  gold. 

3.  PREPARATION  OF  POTASSA,  OR  PURE  POTASH. 

Take  1  part  potashes,  or  pearl  ashes,  and  good  quick  lime  2,  with 
abundance  of  water  ;  boil  for  an  hour,  in  an  iron  or  copper  kettle,  till 
the  fluid  neither  effervesces  with  acids,  nor  precipitates  lime  water.* 
Strain  it  through  a  coarse  brown  towel,  stretched  on  a  frame  with  ten- 
ter hooks,  and  hot  water  should  be  repeatedly  passed  through,  until  we 
have  used  ten  times  as  much  as  the  weight  of  the  carbonate  of  pot- 
ash employed.  The  caustic  fluid  may  be  put  up  in  black  bot- 
tles, and  allowed  to  settle  over  night ;  the  next  morning  it  may  be 
drawn  off  by  a  glass  syphon.  To  avoid  burning  the  rnouth,  the  sy- 
phon tube  may  be  filled  with  water,  and  the  finger  being  pressed  up- 
on the  mouth  of  the  longer  leg,  the  shorter  may  be  dexterously  turn- 
ed into  the  bottle's  mouth,  without  breaking  the  column  in  the  sy- 
phon, the  water  in  which  maybe  allowed  to  run  off, 
and  the  fluid  is  then  saved  for  evaporation. 

In  general,  filtering  succeeds  badly  with  caustic 
alkalies,  unless  very  weak,  as  they  are  apt  to  corrode 
the  filters,  and  paper  can  scarcely  be  used,  unless 
for  small  assays.  If  the  filtering  is  slow,  the  car-- 
bonic  acid  of  the  air  is  apt  to  combine  with  the  alkali, 
and  to  prevent  this,  Mr.  Donovan  contrived  the  an- 
nexed apparatus,  in  which  A  is  the  filtering  funnel, 
whose  mouth  is  obstructed  by  folds  of  linen  ;f  D  is 
the  receiving  vessel,  and  c  is  a  connecting  tube,  to 
prevent,  at  once,  any  communication  with  the  exter-D| 
nal  air,  and  any  accumulation  of  pressure  in  the 
lower  vessel.  { 

(b.)  Boil  the  solution^  down  to  dryness  in  a  clean  iron  kettle  ;  fuse 
the  mass  in  a  silver  crucible ;  pour  it  out  on  a  marble  slab  ;  break  it  up, 
without  delay,  and  cork  it  tight  from  the  air  in  a  glass  bottle.  Cream 
of  tartar,  ignited  in  a  crucible,  dissolved  in  water,  filtered,  boiled 
with  sufficient  lime,  obtained  clear  by  subsidence  and  decantation, 
and  solid  by  evaporation  in  a  silver  vessel,  to  the  consistence  of  oil, 
gives  a  cake  of  the  pure  hydrate  of  potassa,  without  the  trouble  of 
using  alcohol.  It  must  be  put  up  immediately,  in  close  bottles. — Ure. 

*  Taking  care,  provided  the  solution  of  alkali  is  strong,  to  dilute  it  with  pure 
water;  otherwise  it  may  precipitate  the  lime,  by  seizing  the  water,  and  thus  give  a 
delusive  indication. 

t  Better  by  fragments  of  glass,  coarser  below  and  finer  and  finer  above  ;  water  is 
passed  through,  both  before  and  after  an  experiment,  to  remove  impurities,  and  thus 
a  permanent  filter  is  obtained  for  acids  and  other  corrosive  fluids.  D.  O. 

t  Ann.  Phil.  26,  115,  and  Turner,  2d  Ed.  p.  405. 

§  For  a  table  shewing  the  real  quantities  of  alkali  in  aqueous  solutions,  see  Henry. 
Vol.  I,  p.  528, 10th  London  Ed. 


240  ALKALIES. 

This  substance,  mixed  with  lime,  and  fused  and  cast  in  cylindrical 
moulds,  forms  the  caustic  called  lapis  infernalis,  or  lapis  causticus 
of  the  shops.  It  is  said  that'  oxygen  gas  is  disengaged,  during  its  so- 
lution in  water,  and  that  it  varies  apparently  with  the  impurity  of  the 
specimen. 

(c.)  It  is  now  caustic,  but  contains  all  the  soluble  impurities,  chief- 
ly salts,  carbonate,  muriate,  and  sulphate  of  potassa,  silex,  and  oxide 
of  iron  and  manganese,  &c. ;  to  purify  it,  dissolve  it  in  good  alcohol ; 
the  solution  will  be  wine  red  ;  the  watery  solution  of  the  salts  be- 
low is  immiscible  with  the  alcoholic  solution  of  the  alkali,  and  the  solid 
impurities  are  at  the  bottom.  Evaporate  the  alcohol,*  and  finish  the 
process  in  a  silver  basin  or  crucible,  with  moderate  ignition ;  then 
break  up  the  mass,  and  secure  it  from  the  air. 

It  still  contains  a  little  carbonic  acid,  arising  from  the  reaction  of 
the  alkali  on  the  alcohol,  or  absorbed  from  the  air.  The  addition  of 
barytic  water,  previous  to  the  last  evaporation,  will  entirely  remove 
the  carbonic  acid. 

(d.)  Hydrate  of  Potassa. — This  is  the  substance  above  described. 

If  the  whole  of  the  alcohol  be  not  expelled,  the  alkali  will,  on  cool- 
ing, crystallize  in  single  or  double  plates,  needles,  or  tetrahedral  py- 
ramids. This  hydrate  contains  one  proportion  of  water,  9,  and  one 
of  potassa,  which,  as  we  shall  see  under  potassium,  is  represented  by 
48,  and  its  equivalent  is  therefore  57.  Heat  alone  will  not  separate 
the  water  from  it ;  if  it  is  urged,  the  alkali  will  rise  along  with  the 
water,  which  can  be  separated  only  when  it  enters  into  new  combina- 
tions. 

4.  PROPERTIES. 

(a.)  Solid  at  common  temperatures ;  melts  at  300°,  and  is  vola- 
talized  at  low  ignition,  with  a  visible  cloud  of  caustic  fumes,  highly 
acrid ;  color,  white  or  gray ;  taste,  when  strong,  burning  and  in- 
tolerable ;  corrodes  and  destroys  animal  and  vegetable  substances, 
subverting  completely  the  organic  texture,  and  in  a  word,  it  posses- 
ses, in  perfection,  and  in  full  energy,  all  the  characters  of  alkalies, 
mentioned  in  the  introduction  to  their  properties. 

(6.)  It  affects  vegetable  colors  as  ammonia  does ;  in  addition  to 
the  colors  enumerated  under  ammonia,  it  may  be  mentioned  that  a 
strong  infusion  of  the  dried  flowers  of  the  red  rose,  answers  very 
well. — Parkes. 

(c.)  Deliquesces  rapidly  in  the  air,  and  by  absorbing  carbonic 
acid,  becomes  partially  mild  again.  It  acquires  moisture  so  rapidly, 


*  Or  distil  off  and  save  the  first  half  of  it,  in  a  receiver,  as  it  will  be  alcohol  of  a 
good  quality  ;  the  remainder  will  contain  more  water,  and  is  scarcely  worth  sa- 
ving ;  there  is  danger,  besides,  if  we  evaporate  too  low  in  a  glass  vessel,  that  it  will 
be  attacked  by  the  alkali. 


ALKALIES.  241 

from  the  air,  as  speedily  to  change  the  color  of  any  of  the  alkaline 
test  papers  upon  which  it  is  laid.  Turmeric  paper  shews  it  well. 
Crystallized  hydrate  of  potassa,  produces  cold  during  its  solution  in 
water,  while  the  solid  alkali  evolves  heat. 

5.  COMPOSITION. — See  potassium. 

6.  POLARITY. — Electro  positive ;  it  is  attracted  to  the  negative 
pole  in  the  galvanic  circuit. 

7.  ORIGIN. 

From  vegetables  that  have  no  connexion  with  salt  water.  Plants 
yield  more  than  trees ;  the  branches  more  than  the  trunk ;  the  small 
branches  more  than  the  large,  and  the  leaves  most  of  all.  Her- 
baceous plants  yield  more  ashes  and  more  alkali  than  wood.  Fumi- 
tory* is  said  to  yield  more  salt  than  any  other  plant,  and  wormwood 
more  alkali  than  any  other  vegetable. 

One  thousand  pounds  of  the  following  vegetables  yielded  saline 
matter  in  the  following  proportions. 

Wormwood,  748      Fumitory,  360 

Stalks  of  sunflower,  349      Beech,  -    219 

Stalks  of  Turkey  Wheat,  or  Elm,  166 

Maize,  -    198      Fir,       -  -     132 

Vine  branches,    -  162  6  Oak,  -  111 

Fern,  cut  in  Aug.    ^         -    116      Heath,  -  -     115 

Sallow,       -  .      -  102      Aspen,       -  61 

Box,      -  78  Kirwan. 

Fern  leaves  are  used  in  Yorkshire,  in  England,  in  cleaning  cloth 
for  fulling,  and  appear  to  afford  alkali  already  developed. 

In  the  Highlands  of  Scotland,  soap  is  made  from  the  alkali  ob- 
tained from  the  ashes  of  peat. 

The  resinous  and  odorous  woods  afford  little  alkali ;  hence  the 
ashes  of  pine  wood  are  regarded  in  families,  as  worthless  for  soap- 
making. 

Potatoe  tops  yield  a  great  deal  of  alkali. 

The  alkali  of  ashes  arises  principally  from  salts  existing  in  the  veg- 
etable juices,  and  modified  by  the  fire.f 

8.  HISTORY. 

In  an  impure  state,  it  was  known  to  the  ancients  ;  Pliny  states  that 
the  Gauls  and  Germans  formed  soap  of  ashes  and  tallow ;  and  Dr. 
Thomson  thinks  that  their  ashes  were  the  same  with  our  potash. 

*  In  Mr.  Kirwan's  table,  quoted  in  the  text,  Fumitory  is  stated  to  yield  but  about 
half  as  much  saline  matter  as  wormwood. 

t  As  the  alkali  of  vegetables  is  not  an  essential  constituent,  and  is  derived  from  the 
soil,  the  quantity  which  any  plant  will  afford,  will  depend  on  the  qualities  of  the 
earth,  in  which  it  is  raised.  Hence  we  can  account  for  the  discrepancies  of  different 
experimenters  respecting  the  relative  quantities  of  alkali  afforded  by  different  plants. 
— J.  T. 

31 


242  ALKALIES. 

Indeed  it  was  not  known  in  purity  until  1786,  when  Berthollet  gave 
the  process  by  alcohol. 

In  the  ruins  of  Pompeii,  which  was  overwhelmed  by  an  eruption 
of  Vesuvius,  A.  D.  79,  "  a  complete  soap  boiler's  shop  was  discov- 
ered, with  soap  in  it,  which  had  evidently  been  made  by  the  combi- 
nation of  oil  and  alkali,"  and  it  was  perfect,  although  it  had  been 
made  more  than  seventeen  centuries.* 

9.  TESTS  FOR  POTASH. j- 

1 .  With  an  excess  of  tartaric  acid,  it  forms  a  precipitate,  which, 
when  stirred  with  a  glass  rod,  forms  peculiar  white  streaks. 

2.  Muriate  of  platinum  gives  a  yellow  precipitate,  a  triple  salt  of 
platinum  and  potash,  forming,  by  gentle  evaporation  to  dryness,  and 
the  addition  of  cold  water,  "  small  shining  crystals." 

3.  Potash  is  precipitated  by  nothing. — Turner. 

10.  PHARMACEUTICAL  PREPARATION  AND  MEDICAL  USE. 

The  pharmaceutical  preparation  does  not  differ  materially  from  that 
which  has  been  already  described  for  the  purification  of  the  alkali. 

The  principal  use  of  caustic  potash  is  as  an  escharotic  ;  the  cylin- 
drical masses  found  in  the  shops,  are  often  impure,  and  partially  car- 
bonated and  deliquesced,  and  will  sometimes  disappoint  the  practi- 
tioner. That  which  is  carefully  prepared  by  the  process  3.  (a.)  and 
(6.)  is  much  more  powerful.  Potash  is  mixed  with  lime  to  render  it 
milder,  and  less  deliquescent ;  this  is  the  kali  causticum  cum  calce,  of 
the  pharmacopeias.  The  pure  alcoholic  potassa,  prepared  by  the  pro- 
cess 3.  (c.)  is  a  very  certain  caustic,  and  if  fused  at  ignition,  in  the 
conclusion  of  the  process,  broken  up  immediately,  and  put  up  in  close 
vials,  it  discovers,  even  in  several  years,  no  disposition  to  deliques- 
cence, and  preserves  its  crystalline  structure.  J 

Caustic  alkali  has  been  used  as  a  lithontriptic.  When  the  concre- 
tions consist  of  uric  acid,  or  urate  of  ammonia,  there  is  often  a  favor- 
able effect  produced,  but  it  is  difficult  to  persist  long  in  the  use  of 
such  a  remedy,  either  by  the  mouth  or  by  injection  into  the  bladder. 

When  there  is  to  be  a  long  perseverance  in  the  use  of  alkaline 
remedies,  they  must  be  taken  in  a  milder  form,  as  will  be  mention- 
ed under  their  carbonates. 


*  Parkes'  Chem.  Essays. 

t  The  nitrate,  oxalate,  or  oxide  of  nickel,  fused  with  borax,  will  give  a  blue  color 
with  nitre,  feldspar,  or  any  substance  containing  potash,  and  the  presence  of  soda 
does  not  prevent  the  appearance  of  the  color ;  if  nickel  contains  cobalt,  the  glass 
will  have  a  brown  color. — Am.  Journal,  Vol.  XVI,  p.  387. 

$  The  late  celebrated  Dr.  Nathan  Smith  used  to  obtain  this  alkali  from  the  lab- 
oratory, in  all  cases  when  he  wished  an  energetic  and  certain  effect,  and  it  never  dis- 
appointed him.  I  have  many  times  gone  through  the  whole  labor  of  preparing  it 
and  although  the  processes  are  troublesome,  the  result  is  very  valuable,  both  to 
chemistry  and  medicine. 


ALKALIES.  243 

Remarks. — Common  ashes  effervesce  powerfully  with  acids,  and 
they  easily  give  a  solution  with  hot  water,  which  affects  the  taste  with 
the  perception  of  alkalinity,  and  the  test  colors  with  their  appropriate 
changes. 

The  most  familiar  use  of  a  lye  in  families,  is  in  soap  making,  and  a 
principal  cause  of  failure  is,  that  the  alkali  is  not  rendered  caustic  by 
the  application  of  a  sufficient  quantity  of  good  quick  lime.  The  den- 
sity of  the  solution  is  ascertained  by  the  family  hydrometer,  an  egg, 
which  floats  when  the  solution  is  sufficiently  dense  ;  but  it  may  be 
dense  without  being  caustic,  and  if  it  is  not  caustic,  it  will  act  but 
partially  in  forming  soap.  It  should  not  effervesce  with  acids ;  if  it 
does,  it  is  proof  that  the  carbonic  acid  has  not  been  all  withdrawn, 
and  it  may  be  necessary  to  pass  it  through  more  lime.  If  it  is  too 
weak  from  having  too  much  water  in  it,  this  is  easily  removed  by 
boiling  it  down.  The  subject  of  saponification  will  be  mentioned 
again  under  oils,  vegetable  and  animal.  Lye  has  a  valuable  antisep- 
tic effect,  and  is  often  used  in  families,  as  a  part  of  poultices,  and 
also  to  counteract  the  tendency  of  wounds  towards  tetanus. 

This  alkali,  as  it  separates  almost  every  base  from  acids,  and  as  it 
acts  with  great  energy  upon  many  substances,  is  of  great  utility  in 
chemistry.  It  is  an  immediate  antagonist  of  acids,  and  forms  salts 
with  them. 

JHkalimeter. 

This  simple  instrument  is  founded  upon  the  fact  that  100  grains 
of  pure  subcarbonate  of  potash,  are  saturated  by  70  of  strong  sul- 
phuric acid.  The  acid  is  placed  in  a  glass  tube  graduated  into  100 
equal  parts,  and  the  tube  to  the  extent  of  the  graduations,  is  then 
filled  with  water.  The  purity  of  the  alkali  to  be  tried,  will  be  as- 
certained by  the  proportion  of  this  diluted  acid  which  it  requires  for 
perfect  saturation  ;  if  there  be  60  per  cent,  then  100  grs.  will  require 
60  divisions,  and  so  in  proportion ;  if  pure,  it  will  require  it  all. 

If  we  would  ascertain  the  proportion  of  pure  potassa  in  the  salt, 
then  we  must  employ  102  grains  of  the  acid,  and  dilute  it  with  the 
same  quantity  of  water,  requisite  to  fill  the  tube. — Ure. 

This  alkali  is  of  vast  importance  in  glass  making,  soap  making,  in 
medicine,  in  domestic  economy,  and  in  various  arts,  and  it  constitutes 
an  important  article  of  commerce,  especially  from  the  United  States 
to  Europe. 

POTASSIUM. 

1.  DISCOVERY — by  Sir  H.  Davy,  in  October,  1807.* 

*  See  the  Bakerian  lecture  for  that  year,  in  the  Philos.  Trans.  Although  soda 
has  not  been,  as  yet,  described  in  this  work,  I  will  give  the  account  of  the  discovery 
of  its  decomposition  in  connexion  with  that  of  potassa,  as  the  facts  in  the  two  cases 
are  very  similar,  and  are  in  both  perfectly  intelligible.  A  more  particular  state- 
ment of  the  properties  of  sodium  will  be  afterwards  given. 


244  ALKALIES- 

2.  PROCESS. 

DECOMPOSITION  OF  POTASH  AND  SODA. 

1.  By  galvanism. — The  first  attempts  of  Sir  H.  Davy  were  made 
upon  aqueous  solutions  of  potash  and  soda,  but  the  water  alone  was 
decomposed.  He  then  kept  the  potash  in  perfect  fusion  by  an  in- 
genious contrivance ;  it  was  contained  in  a  spoon  of  platinum,  which 
was,  in  the  first  instance,  connected  with  the  positive  side  of  a  battery 
of  one  hundred  pairs  of  six  inches,  highly  charged,  and  the  connexion 
from  the  negative  side  was  made  by  means  of  a  wire  of  platinum. 
A  most  intense  light  was  exhibited,  at  the  negative  wire,  and  a 
column  of  flame  arose  from  the  point  of  contact.  When  the  spoon 
was  made  negative,  and  the  wire  positive,  a  vivid  and  constant  light 
appeared  at  its  point,  and  aeriform  globules  which  inflamed  in  the  at- 
mosphere rose  through  the  potash. 

A  small  piece  of  pure  potash,  slightly  moistened  by  the  air,  so  as 
to  give  it  conducting  power,  was  placed  on  an  insulated  disc  of  pla- 
tinum, connected  with  the  negative  side  of  the  battery  of  the  power 
of  250  pairs  of  6  and  4  inches,  in  a  state  of  intense  activity  and  a 
platinum  wire,  communicating  with  the  positive  side,  was  brought  in 
contact  with  the  upper  surface  of  the  alkali.  The  whole  apparatus 
was  in  the  open  atmosphere. 

There  was  a  fusion  of  the  potash  at  both  surfaces — a  violent  ef- 
fervescence at  the  upper,  and  at  the  lower,  i  small  globules,  having  a 
high  metallic  lustre,  and  being  precisely  similar,  in  visible  characters, 
to  quicksilver,  appeared,  some  of  which  burnt  with  explosion  and 
bright  flame,  as  soon  as  they  were  formed,  and  others  remained  and 
were  merely  tarnished  and  finally  covered  by  a  white  film  which 
formed  on  their  surfaces. 

These  globules  were  the  basis  of  the  potash ;  they  did  not  pro- 
ceed from  the  platinum,  for  they  appeared  equally,  whether  copper, 
silver,  gold,  plumbago,  or  even  charcoal,  was  employed  for  com- 
pleting the  circuit.  The  air  had  no  agency  in  producing  the  glo- 
bules, for,  they  were  evolved  when  the  alkali  was  placed  in  a 
vacuum.* 

The  substance  was  likewise  produced  from  potash,  fused  by 
means  of  a  lamp,  in  glass  tubes,  confined  over  mercury,  and  furnish- 
ed with  hermetically  inserted  platinum  wires,  by  which  the  electrical 
action  was  transmitted.  But  the  glass  was  so  rapidly  decomposed 
by  the  substance  that  the  operation  could  not  be  carried  far. 

The  substance  produced  from  potash  remained  fluid  at  the  tem- 
perature of  the  atmosphere,  at  the  time  of  its  production. 

*  I  repeated  these  experiments  in  1S10,  and  then  obtained  the  metalloids  ;  see 
Bruce's  Journal.  Dr.  (now  Pres.)  Cooper  first  decomposed  pota?h  in  this  country 
by  the  gun  barrel  and  furnace. 


ALKALIES.  245 


THEORY  OF  THE  PHENOMENA. 

These  decompositions  agree  perfectly  with  those  which  have  been 
before  described ;  oxygen  is  evolved  at  the  positive  wire,  and  the 
combustible  with  which  it  was  united  at  the  negative.  When  the 
solid  potash  or  soda  was  decomposed  in  glass  tubes,  the  new  sub- 
stances were  always  evolved  at  the  negative  wire,  and  the  most  deli- 
cate examination  proved  that  the  gas  liberated  at  the  positive  wire 
was  pure  oxygen,  and,  unless  more  water  was  present  than  was  ne- 
cessary to  give  conducting  power  to  the  alkali,  no  gas  whatever  was 
given  out  at  the  negative  wire.*  The  synthetical  proofs  were  equal- 
ly satisfactory. 

The  bases  of  both  alkalies,  when  exposed  to  the  atmosphere,  be- 
came tarnished  and  covered  with  a  white  crust,  which  immediately 
deliquesced  ;  water  was  decomposed,  a  farther  oxidizement  took 
place,  more  white  matter  was  formed,  and  the  whole  became  a  sat- 
urated solution  of  fixed  alkali.  When  the  metallic  globules  were 
confined  over  mercury  in  oxygen  gas  or  common  air,  an  absorption 
took  place,  a  crust  of  alkali  instantly  formed,  and,  for  want  of  mois- 
ture the  process  stopped,  the  interior  being  defended  from  the  action 
of  the  gas.  "  When  the  substances  were  strongly  heated,  confined 
in  given  portions  of  oxygen,  a  rapid  combustion  with  a  brilliant  white 
flame  was  produced  ;  and  the  metallic  globules  were  found  convert- 
ed into  a  white  and  solid  mass,  which,  in  the  case  of  the  substance 
from  potash  was  found  to  be  potash,  and  in  that  from  soda,  soda." 

2.    BY    THE    FURNACE. 

(a.)  The  next  spring,  1808,  potash  was  decomposed  in  a  gun 
barrel,  in  Paris,  by  Gay  Lussac  and  Thenard. 

S6.)  Vary  many  precautions  are  necessary  to  secure  success. -\ 
c.)  Principal  particulars. — Provide  a  clean  sound  gun  barrel 
bent,  so  that  the  middle  shall  be  curved  a  little  downward,  while  the 
end  in  which  the  potash  is  to  be  placed,  shall  incline  gently  upward, 
and  the  other  end  downward  ;  it  must  be  protected  by  a  very  refrac- 
tory lute,  made  of  coarse  siliceous  sand  and  potter's  clay,  with  as  much 
sand  as  can  possibly  be  worked  in,  and  dried  with  extreme  slowness  ; 
place  the  tube  across  a  furnace  ;  potash  in  fragments  is  put  into  the 
elevated  end  out  of  the  furnace  ;  this  is  the  breech  of  the  gun  barrel, 
and  the  breech  pin  is  now  put  in  with  a  lute  ;  clean  iron  turnings  are 
introduced  into  the  belly  of  the  tube  in  the  part  which  lies  in  the  fur- 


*  Some  have  supposed  that  the  hydrogen  combines  with  the  pure  alkali  to 
form  the  metals. 

i  Sec  Recherchcs  Physico-Chimiqucs;  also,  my  translation  of  the  Memoir  of  Gay 
Lussac  and  Thenard,  in  the  Boston  Edition  of  Henry's  Chemistry,  1814 ;  also  An- 
nales  de  Chimie,  LXV,  325;  Memoires  d'  Arcueil,  H,  299. 


246  ALKALIES. 

nace ;  a  stop  cock  and  tube  of  glass  bent  downward  at  right  angles, 
are  fixed  at  the  other  end ;  the  glass  tube  dipping  into  oil ;  both  ends 
are  kept  cold  by  water  or  ice,  till  a  great  heat  is  raised  by  a  powerful 
bellows  blowing  with  a  large  orifice,  so  as  to  introduce  abundance  of 
air ;  the  potash  which  should  have  been  previously  ignited,  before 
its  introduction  into  the  tube,  is  then  slowly  melted  by  a  portable 
furnace,  and  running  down  upon  the  ignited  iron,  is  decomposed  ; 
its  oxygen  is  fixed  in  the  iron,  and  hydrogen  gas  being  abundantly 
disengaged  from  the  tube,  holding  potassium  in  solution,  and  being 
spontaneously  inflammable,  it  flashes  frequently  and  with  intense 
brightness ;  the  potassium  rises  in  vapor  and  congeals  in  the  cold 
end  of  the  tube ;  it  is  then  cut  out  by  a  knife  dipped  in  naptha  and 
is  preserved  under  that  substance.  It  may  be  melted  beneath  it, 
and  is  readily  moulded  by  the  fingers  smeared  with  naptha,  into  any 
form  and  into  pieces  of  convenient  size. 

The  great  difficulty  is  in  preserving  the  gun  barrel  from  oxidation 
and  fusion.* 

Curaudau  of  Geneva,  in  the  same  year,  shewed  that  potash  might 
be  decomposed  by  charcoal  alone,  by  mixing  it  in  powder  with  twice 
its  weight  of  dry  carbonate  of  potash,  and  heating  the  mixture  strong- 
ly in  an  iron  tube  or  spheroidal  iron  bottle.  Prof.  Brunner  has  im- 
proved this  process.  His  apparatus  is  a  spheroidal  wrought  iron 
bottle,  of  one  pint  in  capacity,  and  half  an  inch  thick ;  a  bent  gun 
barrel,  ten  or  twelve  inches  long,  screws  into  the  mouth  of  the  bottle  ; 
the  apparatus  is  well  luted,  and  the  gun  barrel  protected  by  iron  wire 
wound  around  it,  dips  into  a  vessel  of  naptha,  kept  cold  by  ice.  In 
one  experiment,  6  oz.  of  iron  filings,  2  of  charcoal,  and  8  of  fused 
carbonate  of  potash,  were  intimately  mingled  and  heated  in  a  furnace, 
when  140  grains  of  potassium  were  obtained.  It  appears,  accord- 
ing to  the  original  observation  of  Sir  H.  Davy,  that  "  potash  or  pearl- 
ash  is  easily  decomposed  by  the  combined  attractions  of  charcoal  and 
iron ;  but,  it  is  not  decomposable  by  charcoal,  or,  when  perfectly  dry, 
by  iron  alone.  Two  combustible  bodies  seem  to  be  required  by  their 


*  For  improved  processes,  see  Ann.  of  Phil.  New  Series,  VI,  233  ;  Quarterly 
Journal  of  London,  XV,  379;  and  Annales  de  Chim.  XXVII,  340;  also,  Am.  Jour. 
Vol.  VIII,  p.  372.  It  would  be  difficult,  without  an  amount  of  detail  which  is  in- 
consistent with  the  limits  of  this  work,  to  state  all  the  circumstances  that  influence 
the  success  of  this  difficult  process.  Soon  after  the  discovery  of  this  method  of  ob- 
taining potassium,  and  for  several  years  after,  I  labored  much  in  this  field,  having 
gone  many  times,  through  every  part  of  the  operation,  from  the  preparation  of  the 
caustic  alkali  to  its  decomposition,  and  the  evolution  of  its  metal ;  I  was  a  coadju- 
tor at  different  periods,  in  these  experiments,  with  Dr.  Hare,  Prof.  Dewey,  and 
Prof.  Olmsted.  The  statements  of  Gay  Lussac  and  Thenard,  are  extremely  pre- 
cise and  very  full ;  perhaps  I  might  have  added  some  things  from  my  own  expe- 
rience, but  it  is  rendered  unnecessary  by  the  fact,  that  easier  means  have  been 
discovered,  and  potassium,  from  being  one  of  the  dearest  of  all  substances,  is  now 
within  the  reach  of  every  one. 


ALKALIES.  247 

combined  affinities  for  the  effect ;  thus,  in  the  experiment  with  the 
gun  barrel,  iron  and  hydrogen  are  concerned." 

It  would  seem,  however,  that  charcoal  alone  has  succeeded  in  the 
hands  of  Wohler,  who  employed  the  cream  of  tartar,  after  being 
heated  to  redness  in  a  covered  crucible.  The  tartar  may  be  calcined 
in  the  same  iron  bottle  in  which  it  is  to  be  decomposed,  and  it  is  ad- 
vantageous to  mix  a  little  charcoal  with  the  tartar  previous  to  calcin- 
ation ;  300  grains  have  been  obtained  from  24  oz.  of  crude  tartar. 
Prof.  Berzelius  is  said  to  have  obtained  half  a  pound  at  one  opera- 
tion.* 

4.  PROPERTIES. 

(a.)  At  60°  or  70°  Fahr.  it  is  imperfectly  fluid ;  perfectly  so  at 
100°,  and  of  course  at  a  higher  temperature;  when  melted  under 
naptha,  it  cannot  be  distinguished  from  mercury;  at  150°,  two  glo- 
bules will  run  into  one  ;  at  50°,  it  is  a  soft  solid,  plastic  in  the  hand ; 
at  32°  or  lower,  it  is  brittle  ;  breaks  with  brilliant  lustre  ;  and  when 
broken,  exhibits  through  a  microscope,  a  crystallization  in  facets  very 
white  and  splendid ;  at  about  the  heat  of  ignition,  it  is  volatile,  rises 
in  vapor  and  if  air  and  moisture  are  excluded,  condenses  unaltered. 

(b.)  It  is  a  perfect  conductor  of  heat  and  electricity. 

(c.)  Sp.  gr.  about  0.865,  (G.  L.  and  Th.)  0.876,  Bucholz  or  from 
.8  to  .9,  water  being  1 .  Davy.  That  obtained  by  chemical  means,  is 
a  little  heavier,  owing  to  carbon  or  iron  combined  with  it,  but  it  is  suf- 
ficiently pure  for  experiments. 

(d.)  In  the  air  or  by  moisture,  it  is  oxidized  and  becomes  again 
caustic  potash  ;  it  cannot  be  preserved  except  under  naptha ;  if  that 
fluid  has  been  recently  distilled,  and  the  vial  is  full  of  the  fluid,  the 
potassium  may  be  kept  under  it  for  years,  only  it  will  collect  a  film 
of  soap  around  it ;  the  metal  may  be  examined  in  the  air,  if  cover- 
ed with  a  film  of  naptha. 

5.  OXIDES. 

(a.)  The  protoxide  is  formed  by  the  action  of  water,  the  air  being 
excluded  ;  in  that  case,  there  is  great  effervescence,  but  no  flame ; 
40  grains  of  potassium  decompose  9  grs.  of  water  and  evolve  1  gr.  of 
hydrogen  gas,  while  the  other  8  grs.  combine  with  the  metal ;  thence 
the  quantity  of  oxygen  is  inferred  ;  also,  from  the  oxygen  absorbed 
by  potassium  when  it  is  exposed  to  dry  air  ;f  if  it  is  in  thin  slices, 
the  protoxide  is  formed  in  this  manner  also. 

Proportions,  potassium,  83.34,  oxygen,  16.66  =  100.00, 
This  being  nearly  in  the  proportion  of  100  potassium  to  20  oxygen, 
it  follows,  that  20  :  100: :  8  :  40  ;  8  being  the  representative  num- 


*  Graham,  and  Bib.  Univ.  XXII,  36. 

t  According  to  Thenard,  it  is  the  only  metal  that  is  acted  upon  by  perfectly  dry 
oxygen  gas. 


248  ALKALIES. 

her  of  oxygen,  40  becomes  that  of  potassium,  and  therefore  the  num- 
ber for  protoxide  of  potassium  is  48. 

(6.)  Properties  of  the  protoxide,  free  from  water  ;  this  is  its  con- 
dition when  it  is  formed  in  dry  air  or  in  dry  oxygen  gas.  It  is  white, 
very  caustic,  and  fusible  a  little  above  a  red  heat,  but  it  requires  a 
very  high  heat  to  volatilize  it. 

Dissolved  in  water  and  obtained  again,  it  becomes  even  after  igni- 
tion, a  hydrate,  containing  protoxide  of  potassium,  84,  water,  16  =  100. 

Potassium  being  represented  by  40,  oxygen  by  8,  and  water  by 
9,  it  follows  that  the  equivalent  of  hydrate  of  potassa  is  57.  This  is 
the  substance  described  under  potassa.  We  know  riot  whether  the 
solid  anhydrous  protoxide  is  caustic  or  not,  because  its  properties 
cannot  be  examined  in  this  particular,  without  admitting  water  to  it, 
when  it  becomes  a  hydrate.  It  has  already  been  observed,  that  the 
hydrate  melts  at  a  low  heat,  (360°,)  and  is  easily  volatilized.  The 
protoxide  is  formed  also  by  acting  on  potassium  with  a  small  quantity 
of  water,  or  by  heating  potassium  with  common  caustic  potassa,  and 
by  igniting  potash  in  a  crucible  of  gold. 

(C.)  PEROXIDE. 

(a.)  The  white  dry  protoxide  heated  in  oxygen  gas,  absorbs  two 
additional  proportions,  and  becomes  of  an  orange  color. — It  may  be 
formed  also  by  heating  and  burning  potassium  in  oxygen  gas,  or  in 
common  air. 

(b.)  Its  properties. — Color  yellow ;  fusible  with  less  heat  than  hy- 
drate of  potassa,  and  crystallizes  in  laminae  by  cooling.  When  plunged 
into  water,  the  two  additional  proportions  of  oxygen  are  evolved,  and 
it  becomes  hydrate  of  potassa.  Heat  greater  than  that  at  which  it 
was  formed,  expels  the  excess  of  oxygen,  and  brings  it  to  the  state  of 
protoxide  or  true  anhydrous  potash.*  The  heating  must  be  per- 
formed in  a  platinum  tray,  and  the  oxide  covered  with  muriate  of  pot- 
ash. When  mixed  with  combustible  bodies,  and  heated,  it  acts  vig- 
orously upon  them  in  consequence  of  the  two  additional  proportions 
of  oxygen  which  it  contains,  and  it  thus  becomes  potassa.  The  com- 
position of  the  peroxide  is  potassium,  one  proportion  40,  and  oxygen 
3=24,  and  its  equivalent  number  is  64. 

Nitrogen  and  potassium  have  no  action  upon  each  other,  but  if 
potassium  be  heated  in  ammoniacal  gas,  a  fusible  olive  colored  com- 
pound is  formed,  which  consists  of  nitrogen  and  potassium,  and  of 
this  compound  and  ammonia,  and  at  the  same  time,  hydrogen  gas  is 
liberated.  As  it  appears  not  to  be  particularly  important,  we  refer 


*  This  is  said  to  be  so  fixed  as  to  sustain  the  heat  of  a  wind  furnace  without  being 
volatilized ;  it  attracts  water  very  powerfully,  and  generates  intense  heat  during  its 
solution.  The  hydrate  of  the  protoxide  is  easily  volatilized  by  heat. 


ALKALIES.  249 

for  a  more  full  account  of  its  properties  to  Thenard,  Vol.  II,  p.  413, 
4th  Ed. 

6.  MISCELLANEOUS  PHENOMENA. 

(a.)  When  thrown  upon  water,  potassium  floats ,  melts ,  becomes  a 
polished  sphere,  runs  briskly  about,  takes  fires,  and  emits  brilliant 
white  red,  and  violet  light,  with  fumes  of  caustic  potash  ;  sometimes 
rings  of  white  smoke,  from  the  combustion  of  potassuretted  hydro- 
gen are  formed  in  the  air,  and  the  regenerated  alkali,  by  becoming 
red  hot,  often  produces  a  slight  explosion  ;  if  the  piece  is  as  large  as  a 
pea,  the  explosion  is  sometimes  violent,  and  jets  of  the  burning  metal 
are  thrown  about  the  room,  followed  by  white  streaks  of  caustic  potash. 

The  moving  power  that  impels  the  floating  metal,  is  potassuretted 
hydrogen  gas,  aided  by  steam,  both  being  generated  beneath  the 
globule  ;  the  explosion  is  caused  by  the  ignited  caustic  potash,  com- 
bining with  the  water. 

(b.)  On  ice,  potassium  acts  in  a  similar  manner  ;  it  burns  and  melts 
a  hole,  in  which,  the  existence  of  a  solution  of  caustic  potash  is  easi- 
ly ascertained  by  turmeric  paper  ;  it  sometimes  explodes  on  ice. 

(c.)  Placed  on  ignited  iron,  it  burns  in  common  air,  and  brilliantly 
in  oxygen  gas,  producing  abundant  white  alkaline  fumes,  which  are 
soon  condensed  on  the  interior  of  the  glass  vessel. 

(d.)  On  all  the  test  fluids — cabbage,  turmeric,  alkanet,  fyc.  it  burns 
and  produces  the  effect  of  an  alkali,  and  that  although  they  may  have 
been  first  changed  red  by  an  acid :  the  experiment  is  strikingly  exhib- 
ited in  a  small  glass  flask,  containing  the  watery  solution  of  these  colors. 

(e.)  It  flames  on  the  three  strong  minerals  acids,  producing  with 
them  salts  of  the  respective  acids :  the  sulphate  of  potash,  on  ac- 
count of  its  insolubility,  sinks  through  the  fluid  in  white  streaks. 

(f.)  It  dances  about  on  alcohol  and  ether,  gradually  wasting  away, 
but  generally  without  flaming,  and  the  globule  looks  like  polished  silver : 
in  the  very  best  ether  it  sinks,  and  when  it  rises  it  does  not  of  course 
prove  that  it  is  lighter  than  the  ether,  as  it  is  often  made  buoyant  by 
the  hydrogen  generated  beneath  it.  It  discovers  and  decomposes 
even  the  small  quantities  of  water  contained  in  alcohol  and  ether,  and 
being  insoluble  in  the  latter,  it  forms  in  it,  a  turbid  cloud  of  potash, 
while  hydrogen  is  disengaged. 

(#•)  With  °MS  it  slowly  forms  soap,  and  when  kept  even  under 
naptha,  in  vials  carelessly  closed,  it,  in  the  course  of  some  time,  be- 
comes entirely  saponified ;  absorbing  oxygen  first  to  form  alkali,  and 
this  uniting  with  the  naptha  to  form  soap.  Potassium,  when  heated 
in  the  concrete  oils,  (tallow,  spermaceti,  wax,  &c.)  acquires  oxygen 
even  from  them,  gas  rises,  the  base  is  slowly  converted  into  potash, 
and  a  soap  is  formed. 

(h.)  On  test  papers,  if  moist,  it  runs  about,  changes  the  color,  and 
fires  if  there  be  moisture  enough.  We  should  never  touch  it  with 

32 


250  ALKALIES. 

moist  hands,  as  it  immediately  blazes,  and  we  have  in  that  case,  both 
the  actual  and  potential  cautery. 

(i.)  Hydrogen  gas,  heated  in  contact  with  potassium,  dissolves  it, 
and  becomes  spontaneously  inflammable,  but  loses  this  property  by 
standing,  and  deposits  potassium  again.  A  solid  compound  of  potas- 
sium and  hydrogen,  is  formed  by  heating  the  gas  and  metal  together, 
with  a  spirit  lamp.  It  is  gray,  dull,  infusible,  and  not  inflammable, 
except  at  a  high  heat,  when  it  burns  vividly. 

7.  POWERS  OF  COMBINATION. 

They  are  almost  universal,  as  will  appear  farther  on  ;  it  unites  with 
iodine,  chlorine,  the  metals  and  most  of  the  combustibles,  &c.  and  it 
decomposes  the  acids,  most  of  the  oxides  and  salts,  and  animal  and 
vegetable  bodies,  and  few  substances,  simple  or  compound,  are  un- 
affected by  it.  Its  greatest  prerogative  however  is  to  attract  oxygen, 
which  it  takes  from  every  thing,  even  from  glass  and  stones,  and 
from  the  firmest  compounds,  both  natural  and  artificial. 

8.  In  relation  to  the  state  of  our  knoivledge,  it  is  an  element. — The 
most  singular  circumstance  in  the  character  of  potassium  is  its  levity : 
it  resembles  the  metals  very  much  in  the  greater  number  of  its  prop- 
erties, but  differs  from  them  remarkably  in  specific  gravity,  while  in 
its  extreme  inflammability  it  is  assimilated  to  the  most  combustible 
bodies.* 

9.  POLARITY  AND  COMBINING  PROPORTION. 

Like  other  inflammable  and  metallic  bodies,  it  resorts  to  the  nega- 
tive pole  in  the  galvanic  circuit,  and  is  therefore  electro-positive.  Its 
combining  number  or  chemical  equivalent  has  already  been  stated  to 
be  40,  hydrogen  being  l.f 

10.  USES. — As  yet  they  are  exclusively  philosophical.     In  the 
hands  of  the  chemist,  it  is  a  fine  instrument  of  analysis,  especially  in 
the  agencies  which  it  exerts  upon  oxygen.     It  is  a  splendid  substance 
for  experiment,  admitting  of  many  beautiful  and  instructive  modes  of 
exhibition.     From  the  improved   modes  of  obtaining  it  which  have 
been  discovered,  there  seems  little  reason  to  doubt  that  it  may  be 
manufactured  to  any  extent  that  may  be  required,  and  its  introduction 
as  a  new  means  of  annoyance  and  destruction,  would  perhaps  not  be 
improbable,  were  it  not  that  it  might  prove  nearly  equally  dangerous 
to  friend  and  foe. 


*  These  properties,  with  the  remarkable  fact,  that  during  the  galvanic  decomposi- 
tion of  the  alkali,  although  oxygen  is  evolved  at  the  positive  pole  there  is  no  hydrogen 
given  off  at  the  negative,  led  to  the  presumption  that  potassa  is  not  a  compound  of 
oxygen  and  potassium,  but  of  potash  and  hydrogen;  the  oxygen  arising  from  the 
decomposition  of  water,  and  the  hydrogen  of  that  fluid  going  into  union  with  the 
alkali  to  produce  potassium.  For  an  ingenious  discussion  of  these  and  some  other 
similar  views,  see  Murray,  6th  ed.  Vol.  II,  p.  27. 

t  Mr.  Murray  has  stated  some  reasons  why  it  may  rather  be  supposed  to  be  41, 
see  as  above. 


ALKALIES.  251 


SEC.  III. — SODA. 

1.  NAMES. — The  caustic  soda  was  always,  and  is  still  unknown 
to  commerce ;  anciently,  the  carbonate  was  called  natron,  natrum 
and  nitrum,  whence  the  nitre  of  the  Scriptures.     It  is  mentioned  in 
the  Bible,  as  a  detergent,  and  as  disagreeing  (effervescing  ?)  with  vin- 
egar ;  both  of  which  qualities  belong  to  the  carbonate  of  soda,  but 
neither  of  them  to  nitre.     In  Africa,  they  call  it  trona;  on  the  shores 
of  the  Mediterranean,  soda  and  barilla.     It  has  been  called  marine 
and  mineral  alkali.     The  term  soda  is  now  universally  used. 

2.  HISTORY. — Indicated  by  Geber,   an  Arabian  chemist,  in  the 
ninth  century,  but  confounded  with  potash  till  after  the  middle  of  the 
last  century;  and  unknown  in  its  pure  state  until  the  discovery  of  the 
carbonic  acid.     Effervescence  with  acids  was  formerly  considered 
as  characteristic  of  soda  as  well  as  of  the  other  alkalies,  but  it  be- 
longs to  them  in  the  state  of  carbonate  only,  and  not  in  the  pure  state. 

3.  POINTS  OF  SIMILARITY  BETWEEN  IT  AND  POTASSA. 

(a.)  Their  history  is  so  nearly  the  same,  that  it  is  necessary  only 
to  indicate  the  difference. 

(b.)  All  that  respects  the  preparation  is  identical,  and  their  prop- 
erties are  very  similar. 

4.  SODA  ORIGINATES    FROM  *MARATIME  AND  MARINE  PLANTS,  the 

algae  fuci,  salsola  soda,  &LC.  :  the  plants  are  dried,  burned  and  lixivi- 
ated, and  the  lixivium  evaporated  to  dryness.  The  crude  soda  of 
commerce,  called  barilla,  is  the  incinerated  salsola  soda:  kelp,  a 
coarser  variety,  is  the  incinerated  sea  weed,  and  often  contains  only 
from  2  to  5  per  cent  of  alkali ;  white  good  barilla  contains  20  per 
cent.  The  crystallized  carbonate  of  soda  of  commerce  is  obtained 
either  from  the  calcination  of  the  sulphate  with  charcoal  and  chalk  in 
a  reverberatory  furnace,  or  by  decomposing  the  muriate  of  soda  by 
carbonate  of  potash. — Ure. 

5.  PROPERTIES. 

(a.)  Caustic  soda  is  at  first  deliquescent  in  the  air,  like  potassa, 
but  unlike  that  alkali  it  never  runs  into  the  consistency  of  an  oily  fluid ; 
for  it  soon  becomes  efflorescent,  from  combination  with  the  carbonic 
acid  contained  in  the  atmosphere :  a  change  which  potash  never  un- 
dergoes. 

(b.)  Caustic  soda  is  in  the  form  of  gray  sub-crystalline  masses, 
which  can  scarcely  be  distinguished  from  potassa,  by  the  eye  or  by 
any  sensible  properties. 

6.  The  force  of  attraction  in  soda  for  the  acids,  is  inferior  to  that 
of  potassa:  the  soda  salts  are  decomposed  by  potassa. 

*  Salsola  is  a  maratime  plant,  (i.  e.  it  grows  on  the  sea  shore,)  but  the  algae  are 
marine;  the  carbonate  of  soda  of  truly  marine  plants  only,  yields  iodine.— J.  T. 


$52  ALKALIES. 

7.  Soda  with  oil  forms  hard  soap — potash  soft;  and  soda  is  per- 
haps a  little  less  caustic  than  potassa. 

8.  Distinctive  characters. 

(a.)  It  forms  different  combinations  with  acids ;  for  instance,  the 
sulphate  of  soda  is  very  soluble  in  water ;  that  of  potash  the  opposite. 

(b.)  Its  salts,  suspended  upon  platinum  wire,  impart  a  rich  yellow 
color  to  the  blowpipe  flame. — Turner. 

(c.)  Muriate  of  platinum  and  tartaric  acid  give  no  precipitates  with 
salts  of  soda :  the  opposite  is  true  of  potash. 

9.  USES  AND  IMPORTANCE. — Soda  is  scarcely  inferior  in  this  re- 
spect to  potassa :  in  soap  and  glass  making  it  is  largely  used,  and  it  is 
preferred  for  the  finest  articles.     In  the  form  of  carbonate  it  is  much 
used  in  medicine  as  an  antacid :  in  medicine  the  caustic  soda,  is  not 
used,  having  no  advantage  over  potash. 

10.  The  distinction  of  vegetable  and  mineral*  alkali  is  unfounded; 
for  both  are  found  in  plants,  and  both  also  in  stones  and  various  min- 
erals.    Still  it  is  true  that  potash  is  found  in  most  plants,  and  soda  in 
those  only  which  are  connected  with  saline  sources ;  on  the  other 
hand,  solid  mineral  salt,  the  ocean  and  other  saline  waters,   and  the 
soda  lakes  and  incrustations,  present  great  quantities  of  that  alkali  in 
the  mineral  kingdom. f 

11.  POLARITY. — In  the  galvanic  circuit,  soda  goes  to  the  negative 
pole,  and  is  therefore  electro-positive.     Its  combining  weight  is  32. 

REMARKS. — In  commerce,  we  never  see  caustic  soda  ;  in  its  pur- 
est form,  in  the  shops,  it  is  always  in  semi-crystalline  masses  of  car- 
bonate, called  sal  soda. 

The  purest  fossil  alkali,  obtained  from  the  efflorvescence  on  plaster 
walls,  contains  about  60  J  of  its  weight  of  alkali  in  crystals. 

Alkali  manufactured  at  Liverpool,  -       49 

Fossil  alkali  from  India,      -  28 

Best  Alicant  Barilla,  -       26  J 

Sicilian  Barilla,     -  23 

The  richest  Kelp,  made  in  Norway,  the  Orkney  Islands, 

and  Skye,  6£ 

The  general  produce  of  Scottish  Kelp,       -  2£J 

There  are  associated  with  the  soda  in  sea-weed,  muriate  and  sul- 
phate of  soda,  hydriodate  of  potash,  or  soda,  and  portions  of  lime, 
magnesia,  silica,  and  alumina.  There  is  also  more  or  less  of  sul- 


*  Potash  was  formerly  culled  the  vegetable  alkali,  and  soda  the  mineral. 

t  As  felspar,  which  constitutes  so  large  a  proportion  of  granite,  whose  detritus 
forms  a  considerable  part,  oi  our  soils,  contains,  on  an  average,  at  least  10  per  cent,  of 
potassa,  this  alkali  may  after  all  be  more  abundant  than  soda. — J.  T.  and  C.  U.  S. 

t  Black's  Lect. 


ALKALIES.  253 

phur,  which  is  often  to  a  degree  separated  by  the  efflorescence  of 
the  soda,*  in  the  form  of  carbonate. 

When  soda  plants  are  made  to  vegetate  away  from  saline  sources, 
the  quantity  of  soda  constantly  diminishes,  and  eventually  they  afford 
only  potash. — Murray.  Although  soda  is  separated  from  its  com* 
binations  with  acids  by  potash,  it  exceeds  that  alkali  in  its  power  of 
neutralizing  acids,  in  the  proportion  of  4  to  6,  or  2  to  3,  its  equiva- 
lent being  32,  and  that  of  potash  48. 

•Mode  of  ascertaining  the  proportion  of  real  alkali  in  the  soda 
of  Commerce. 

Take  sulphuric  acid  of  the  specific  gravity  of  1.10,  w^hich  is  gene- 
rally prepared  by  mixing  one  part,  by  weight,  of  the  best  acid  of  the 
shops,  with  six  of  water. 

Pulverize  finely,  an  average  sample  ;  take,  say  100  grains,  and 
add  to  it  2  oz.  measures  of  pure  water,  agitating  it  occasionally,  for 
a  few  hours ;  after  subsidence,  decant,  add  more  water,  and  again 
allow  the  solid  matter  to  subside ;  decant  again,  and  filter  the  fluids, 
and  lastly,  wash  the  solid  residuum  on  a  filter,  until  the  water  drops 
tasteless,  and  no  longer  affects  the  test  colors.  Mix  the  different 
fluids,  and  concentrate  them,  by  boiling,  to  the  volume  of  2  or  3  oz. 
measures.  In  a  vial  of  known  weight,  place  2  oz.  of  the  acid,  sp. 
gr.  1.10,  and  then  add  it  cautiously  to  the  alkali,  till  effervescence 
ceases,  and  the  test  papers  are  no  longer  altered.  Sulphur  will  be 
precipitated.  Now  see  how  much  acid  remains.  It  having  been 
ascertained  by  previous  trials,  that  100  grains  of  dry  alcoholic  potas- 
sa,  require  520  grains  of  the  acid,  of  the  sp.  gr.  1.10,  for  saturation, 
and  that  100  grains  of  alcoholic  soda  require  812  grains  of  the  same 
acid,  it  is  easily  calculated  how  much  real  alkali  there  was  in  the  por- 
tion subjected  to  examination.  Trial  is  made  also,  for  potash,  and 
the  test  used  is  muriate  of  platinum ;  there  will  be  a  yellow  precipitate 
if  potash  is  present ;  otherwise  none.  If  muriate  of  potash  should 
be  suspected,  since  the  muriate  of  platinum  detects  all  the  salts  of 
potash,  it  may  be  knovvn  by  adding  a  little  sulphuric  acid  to  the  alka^ 
line  lixivium,  when  there  will  be  fumes  of  muriatic  acid  gas,  if  the 
muriate  of  potash  is  present. f 

SODIUM. 

1.  DISCOVERY. — By  Sir  H.  Davy,  at  the  same  time  with  potas- 
sium, October,  1807. 


*  Mr.  Parkes,  in  his  essays,  mentions  that  some  dealers  refuse  to  buy  theefflores- 
ced  carbonate  of  soda,  thinking  it  to  be  spoiled,  whereas  it  is  really  in  a  good  degree 
purified. 

t  Parkes'  Cheru.  Essays,  Vol.  II. 


254  ALKALIES. 

2.  MODES  OF  OBTAINING. — The  same  as  those  described  for  po- 
tassium ;  only  the   decomposition  of  soda  is  more   difficult,  requir- 
ing a  higher  voltaic  power,   and  in   the  process  by  the  furnace,  a 
greater  degree  of  heat ;  a  mixture  of  potash  and  soda  is  more  easily 
decomposed,  and  affords  an  alloy  of  the  two  metals. 

Dry  muriate  of  soda  or  chloride  of  sodium  is  decomposed  by  po- 
tassium, with  the  aid  of  heat,  and  sodium  is  evolved  ;  it  is  done  in  an 
iron  tube. 

3.  PROPERTIES. 

(a.)  Extremely  similar  to  those  of  potassium. 

(b.)  Rather  more  solid  at  the  common  temperature — under  naptha, 
brilliant  like  silver,  and  quite  as  white. 

(c.)  Very  malleable  ;  by  pressure  of  a  platina  blade,  a  globule  TV 
or  y'g-  of  an  inch  in  diameter,  is  made  to  cover  £  of  a  square  inch,  and 
this  property  does  not  diminish  even  when  it  is  cooled  down  to  32°. 

(d.)  Several  globules,  by  strong  pressure,  unite  into  one,  and  it  is 
therefore  capable  of  being  welded  at  the  common  temperature,  while 
iron  and  platinum  require  full  ignition. 

(e.)  It  merely  floats  on  ivater;  the  sp.  gr.  at  59°  Fahr.  is  sup- 
posed to  be  0.972,  water  being  1. 

(f.)  Less  fusible  than  potassium ;  softens  at  120°,  is  perfectly 
fluid  at  180°  or  200°,  and  readily  melts  under  naptha. 

(g.)  J^aporizable,  but  at  what  exact  temperature  is  unknown,  for 
it  does  not  rise  in  vapor  at  the  fusing  point  of  plate  glass,  but  is  dis- 
tilled at  an  intense  heat. 

(A.)  Tarnished  by  common  air,  but  not  by  air  artificially  dried,  un- 
less heated  in  it. 

fi.)  Heated  to  fusion,  it  burns  with  scintillations  and  white  flame. 
)  On  ivater,  it  melts,  appears  like  a  globule  of  floating  silver, 
and  wastes  rapidly  away,  but  without  emitting  light,  unless  the  water 
be  hot,  when  it  scintillates  and  flames  ;  there  is  no  combination  of  the 
sodium  with  the  hydrogen  evolved  by  the  decomposition  of  the  wa- 
ter, on  the  surface  of  which  it  has  a  rapid  motion,  owing  to  the  causes 
mentioned  under  potassium.  It  burns  in  chlorine  gas  with  bright  red 
scintillations,  and  muriate  of  soda  is  the  result.  When  plunged  be- 
neath it,  it  decomposes  water  with  violent  effervescence,  and  a  loud 
hissing  noise ;  soda  is  formed,  and  hydrogen  evolved,  but  there  is  no 
luminous  appearance.  On  moistened  paper,  or  in  contact  with  a 
small  globule  of  water,  as  there  is  nothing  to  carry  off  the  heat,  the 
sodium  usually  inflames.  The  action  on  alcohol  and  ether,  is  the 
same  as  that  of  potassium.  In  the  action  of  sodium  on  the  oils, 
and  on  naptha,  on  sulphur,  and  phosphorus,  on  mercury  and  sev- 
eral other  metals,  there  is  almost  a  perfect  similarity  with  the  ac- 
tion of  potassium.  The  soaps  are  of  a  darker  color,  and  less  solu- 
ble ;  the  combination  with  sulphur,  (effected  as  in  the  case  of  potas- 
sium in  close  vessels  filled  with  the  vapor  of  naptha,)  is  attended  with 


ALKALIES.  255 

very  vivid  light,  and  much  heat,  and  often  explosion.  The  amalgam 
of  mercury  and  sodium  seems  to  form  triple  compounds  with  other 
metals;  Sir  H.  Davy  thought  that  the  mercury  remained  in  combina- 
tion with  iron  and  platinum,  after  the  sodium  was  alkalized,  and  sep- 
arated by  deliquescence.  The  amalgam  forms  a  triple  compound 
of  a  dark  gray  color  with  sulphur. 

(k.)  Inflames  on  the  strong  acids,  forming  salts  with  soda  for  a 
basis ;  the  nitric  acid,  as  usual,  acts  with  the  most  energy. 

4.  OXIDES. 

(a.)  Protoxide. — Sodium  combines  spontaneously  with  oxygen  re- 
producing soda,*  but  its  attraction  for  oxygen  appears  to  be  less  en- 
ergetic than  that  of  potassium  ;  the  process  is  slower,  and  the  deli- 
quescence of  the  alkali  produced  is  not  so  rapid.  The  combination 
is  accelerated  by  heat,  but  combustion  in  oxygen  gas  does  not  take 
place  till  near  ignition ;  it  then  burns  beautifully  with  a  white  flame 
and  bright  sparks,  and,  in  common  air,  the  flame  is  similar  to  that 
from  burning  charcoal,  but  much  brighter.  Sodium  heated  with  so- 
da, is  said  to  divide  the  oxygen  between  them,  producing  a  deep 
brown  fluid,  which,  on  cooling,  becomes  a  dark  gray  solid,  and  at- 
tracts oxygen  again  from  air  and  water.f 

The  protoxide  is  produced  also  by  burning  sodium  in  dry  common 
air,  the  sodium  being  in  excess,  or  by  the  action  of  water.  This 
protoxide  is  caustic  soda;  its  color  is  gray,  fracture  vitreous,  does 
not  conduct  electricity,  fusible  at  a  red  heat,  combines  with  water, 
with  great  heat,  and  produces  hydrate  of  soda,  which  is  white,  crys- 
talline and  more  fusible  and  volatile  than  before.  Its  constitution  is, 
1  proportion  of  sodium,  24 

1          "  oxygen,  8 

And  the  equivalent  of  anhydrous  soda  is  32 

It  combines  with  water,  as  already  remarked,  with  great  energy,  be- 
coming a  hydrate,  and  the  water  cannot  be  expelled  by  ignition. 
The  constitution  of  the  hydrate, 

1  proportion  of  protoxide,  32  per  cent.  22  J  water.  J 

1          "  water,  9 

41 

(b.)  Deutoxide  of  sodium. — Burn  sodium  in  an  excess  of  oxygen 
gas,  or  heat  the  protoxide  in  that  gas ;  the  protoxide  is  always  formed 


*  This  happens,  of  course,  if  it  is  not  carefully  kept;  I  have  lost  masses  of  sodium 
in  this  manner;  the  metal  turns  into  white  caustic  soda,  and  eventually  effloresces 
in  the  form  of  carbonate,  at  the  same  time  enlarging  its  volume  very  much. 

t  It  is  doubted  whether  it  is  not  a  mixture  of  the  metal  with  soda. 

J  See  Mr.  Dalton's  table  of  the  quantities  of  soda,  in  different  solutions,  Henry, 
Vol.  I,  p.  558,  10th  Lon.  Ed. 


256  ALKALIES. 

first,  and  then  more  oxygen  is  absorbed,  and  the  peroxide  is  generated. 
The  color  of  this  oxide  is  yellowish  green  or  orange;  it  is  fusible  ; 
a  non-conductor  of  electricity,  and  when  thrown  into  water,  it  gives 
out  its  excess  of  oxygen. 

Its  composition  according  to  Davy,  is  sodium,  -       75 

oxygen,     -  25 

100 

Its  constitution  is  stated  to  be  1  proportion  of  sodium  24,  and  1J 
of  oxygen  =12  =  36,  but  as  this  introduces  a  fraction,  it  is  probable 
that  our  knowledge  is  not  precise. 

The  peroxide  acts  upon  most  combustible  bodies  with  deflagration. 
According  to  some,  the  peroxide  is  composed  of  two  proportions,  of 
Sodium,  48 

Oxygen  3,  -  =24 

72   would 

then  be  its  equivalent  or  representative  number  ;  of  the  truth  of  this 
view,  there  seems  to  be  no  direct  proof. 

5.  POWERS  OF  COMBINATION. 

They  are  very  extensive,  like  those  of  potassium  ;  to  which  how- 
ever it  yields  an  energy  of  affinity,  as  is  evident  in  the  case  of  the 
decomposition  of  common  salt  by  potassium. 

6.  POLARITY. 

Like  potassium,  it  is  attracted  to  the  negative  pole  in  the  galvanic 
series,  and  in  this  way  it  was  first  discovered. 

7.  DIFFUSION. 

Sodium  exists  very  extensively  in  the  carbonate,  sulphate,  muriate 
and  other  forms  of  soda  salts ;  it  is  found  in  some  plants,  especially 
marine  ones,  and  in  many  stones  and  rocks. 

Remarks. — The  great  prerogative  of  sodium  is  to  attract  oxygen, 
in  which  function,  it  is  inferior  only  to  potassium.  Both  these  re- 
markable bodies  are  endued  with  such  a  degree  of  activity,  and  their 
chemical  relations,  are  so  numerous,  as  almost  to  realize  the  brilliant 
suggestion  of  their  illustrious  discover,*  that  they  approach  to  the  char- 
acter of  the  imaginary  alkahest  of  the  ancient  alchemists.  Their  dis- 
covery has  placed  in  our  hands  new  means  of  investigation,  and  of 
beautiful  and  splendid  experiment.  Nothing  could  be  more  unex- 
pected, than  that  common  salt  and  sea  weed  should  contain  a  metal, 
or  wood  ashes  another.  In  the  present  state  of  our  knowledge,  we 
must  regard  potassium  and  sodium  as  elements.  As  they  exist 
abundantly  in  minerals,  we  can  understand  how,  in  the  processes  of 


*  Applied  by  him  more  particularly  to  potassium. 


ALKALIES.  257 

vegetable  life,  they  should  become  constituent  parts  of  plants.  It  has 
been  already  stated,  that  hydrogen  has  been  supposed  by  some,  to 
be  one  of  their  constituent  principles  ;  a  suggestion  which  is  coun- 
tenanced by  their  levity,  and  by  the  fact,  so  contrary  to  what  is  found 
to  be  true  in  most  other  cases,  that  their  oxides  are  heavier  than  the 
metals  which  they  contain.* 

SEC.  IV.  —  LITHIA. 


1.  NAME.  —  From  Xidos,  a  stone,  or  Xidsios,  stony. 

2.  DISCOVERY. 

Detected  in  the  year  1818,  by  Mr.  Arfwedson,  in  the  petalite,  which 
contains  from  3  to  8  per  cent.  ;  in  the  triphane  or  spodumene,  •)•  there 
is  8  per  cent,  and  in  crystallized  lepedolite,  4  per  cent.  ;  it  has  been 
found  also  in  the  green  and  red  tourmaline,  and  in  several  varieties 
of  mica. 

3.  PROCESS. 

(a.)  Fuse  the  powdered  petalite,  1  part,  with  carbonate  of  pot- 
ash 3  parts,  dissolve  in  muriatic  acid  —  evaporate  to  dryness  —  digest 
in  alcohol,  which  takes  up  the  muriate  of  lithia  and  little  else  ;  this  so- 
lution is  evaporated  to  dryness,  and  the  residuum  again  dissolved  in 
alcohol,  which  gives  the  muriate  pure  ;  it  is  then  digested  with  car- 
bonate of  silver,  to  form  carbonate  of  lithia  ;  this  being  decomposed 
by  lime  or  barytes,  gives  pure  lithia,  which  must  be  evaporated  to 
dryness,  away  from  the  air.J 

(6.)  Another  process  by  Berzelius,  is  as  follows  :  —  Mix  2  parts  of 
fluor  spar,  and  3  or  4  of  sulphuric  acid,  with  1  of  powdered  petalite 
or  spodumene,  and  apply  heat  till  the  acid  vapors,  consisting  princi- 
pally of  silicated  fluoric  acid,  have  ceased  ;  thus  the  silica  is  remov- 
ed, and  the  alumina  and  lithia  unite  with  the  sulphuric  acid,  in  the 
form  of  sulphate  ;  that  of  alumina  is  decomposed,  and  the  earth  pre- 
cipitated by  boiling  with  pure  ammonia.  Ignition  expels  the  sul- 
phate of  ammonia,  and  the  pure  sulphate  of  lithia  remains,  which  is 
easily  converted  into  the  carbonate,  and  the  carbonic  acid  being  ex- 
pelled from  this,  we  obtain  the  pure  lithia. 


*  It  is  however  sufficient  to  caution  us  against  admitting  conjectures  in  such  cases, 
that  soda  was  formerly  suspected  to  be  composed  of  magnesia  and  nitrogen,  and 
Fourcroy,  in  his  large  work,  has  stated  the  reasons  why  he  with  some  other  chem- 
ists, conjectured  that  potash  was  composed  of  lime  and  nitrogen,  and  soda  of  magne- 
sia and  nitrogen. 

t  In  the  spodumene  and  petalite,  the  lithia  is  combined  with  silica  and  alumina; 
but  in  the  lepidolite  and  in  the  lithion  mica,  it  is  combined  also  with  potassa,  and  to 
avoid  contamination  with  this  alkali,  the  lithia  should  be  prepared  from  the  spodu- 
mene and  petalite. — Turner. 

t  For  other  processes,  see  Ann.  de  Chim.  et  de  Phys.  X.  86 ;  also,  Henrv,  Vol.  I, 
p.  572,  and  Thenard,  Vol.  II,  p.  323,4th  Ed. ;  Ure's  Diet.  3d  Ed.  p.  582.  * 

33 


258  ALKALIES. 

4.  PROPERTIES. 

(a.)  Color  white ;  not  deliquescent,  but  absorbs  carbonic  acid  by 
exposure  to  the  air,  and  becomes  a  carbonate. 

(&.)  Very  soluble  in  water,  but  less  so  than  potassa  and  soda,  and 
scarcely  soluble  at  all  in  alcohol ;  acrid,  caustic,  acts  on  colors  as 
the  other  alkalies  do. 

(c.)  Heated  with  platinum,  it  acts  on  the  metal ;  place  on  platinum 
foil,  with  a  small  excess  of  soda,  a  piece  of  a  lithia  mineral  as  large 
as  a  pin's  head,  and  heat  it  with  the  blowpipe  for  two  minutes  ;  a  dark 
color  or  dull  yellow  trace  appears  near  the  fused  alkali,  and  the  met- 
al is  oxidized  by  aid  of  the  lithia  and  the  air,  while  it  is  not  affected 
under  the  soda.  The  soda,  by  combining  with  the  other  principles 
of  the  stone,  liberates  the  lithia. 

(d.)  Lithia  has  a  higher  neutralizing  power  than  potassa  and  soda, 
or  even  than  magnesia ;  its  phosphate  and  carbonate  are  sparingly 
soluble,  its  chloride  is  deliquescent  and  soluble  in  alcohol,  and  this 
solution  burns  with  a  red  flame ;  all  the  salts  of  lithia  give  a  red 
color  when  heated  on  a  platinum  wire  before  the  blowpipe.  "  Lithia 
is  distinguished  from  the  alkaline  earths  by  forming  soluble  salts  with 
sulphuric  and  oxalic  acids,"  and  the  carbonate, *  although  difficultly 
soluble  in  water,  stains  turmeric  paper  brown.  The  muriate  and  ni- 
trate are  deliquescent ;  the  concentrated  lithia  salts  mixed  with  a 
strong  solution  of  carbonate  of  soda,  deposit  carbonate  of  lithia. — 
Bcrzelius. 

Some  of  these  properties  have  been  mentioned  in  anticipation,  and 
others  are  omitted  or  reserved  for  their  more  appropriate  place. 

5.  DECOMPOSITION. 

The  metallic  base  was  evolved  by  Sir  H.  Davy,  by  galvanism,  but 
it  was  too  rapidly  oxidized  to  be  collected  ;  and  the  metal  was,  how- 
ever seen  to  be  white  like  sodium,  and  burned  with  bright  scintilla- 
tions. Composition  supposed  to  be — lithium,  56.50,  oxygen,  43.50 
=  100.00,  or  by  Dr.  Thomson,  lithium  10,  which  he  supposes  to 
be  its  equivalent  number,  and  oxygen  1  proportion  8  =  18,  for  the 
equivalent  of  the  alkali. 


*  Like  the  earthy  carbonates,  and  it  therefore  forms  an  exception  to  the  general 
characters,  stated  p.  230,  (d.) 


I:\KTFLV  259 


EARTHS. 

LIME BARYTA STRONTIA MAGNESIA SILICA ALUMINA GLU- 

CINA ZIRCONIA    AND    YTTRIA. 

Introductory  Remarks. 

In  the  plan  of  this  work,  and  in  connexion  with  the  alkalies,  some 
objections  have  been  stated  to  the  prevailing  mode  of  arranging  most 
of  them,  and  all  the  earths,  under  the  metals.  With  .  respect  to  the 
earths,  this  course,  though  highly  inconvenient,  would  perhaps  be 
somewhat  less  so  than  in  relation  to  the  alkalies ;  but  I  decidedly  pre- 
fer to  preserve  the  old  division  of  earths,  notwithstanding  the  inter- 
esting discovery  that  most,  if  not  all,*  of  them  are  metallic  oxides. 
Here,  as  in  the  case  of  the  fixed  alkalies,  there  can  be  no  difficulty  in 
pursuing  the  analytical  course,  by  proceeding  from  the  compound  to 
its  principles, — first  describing  the  earth,  and  then  its  composition  ; 
and  reverting  again  to  the  metallic  bases  of  the  earths,  when  we 
come  to  the  metals.  The  great  advantage  proposed  in  pursuing  this 
course  is,  that  we  are,  as  early  as  possible,  put  in  possession  of  a 
knowledge  of  the  properties  of  these  important  bodies,  and  that  the 
natural  order  of  earths  will  remain  unbroken ;  for,  as  Dr.  Ure  (Diet.) 
very  justly  remarks,  "  whatever  may  be  the  revolutions  of  chemical 
nomenclature,  mankind  will  never  cease  to  consider  as  earths,  those 
solid  bodies  composing  the  mineral  strata,  which  are  incombustible, 
colorless,  not  convertible  into  metals  by  all  the  ordinary  methods  of 
reduction,  or  when  reduced  by  scientific  refinements,  possessing  but 
an  evanescent  metallic  existence,  and  which  either  alone,  or  at  least 
when  combined  with  carbonic  acid,  are  insipid,  and  insoluble  in 
water." 

Nearly  the  whole  crust  of  our  planet  is  composed  of  these  bodies ; 
for,  the  combustibles,  and  alkalies,  and  the  metals,  properly  so  called, 
form  but  a  very  small  proportion  of  the  whole.  Nine  bodies  have  been 
distinguished  by  chemists,  to  which  the  name  earth  has  been  given  ; 
they  are,  as  enumerated  at  the  head  of  this  division,  Lime,  Baryta, 
Strontia,  Magnesia,  Silica,  Alumina,  Glucina,  Zirconia,  and  Yttria. 

The  three  latter  are  of  little  consequence,  either  in  a  scientific  or 
practical  view,  and  seem  chiefly  important  in  determining  the  con- 
stitution of  some  few  gems,  and  of  a  few  other  minerals,  most  of 
them  rare.  Of  the  remaining  six,  the  most  abundant  is  silica  ;  lime, 
is  in  this  respect,  the  next ;  then  follows  alumina,  and  then  magnesia ; 


*  The  base  of  silica  seems  to  have  no  claim  to  be  called  a  metal ;  should  it  be 
melted  it  may,  perhaps,  exhibit  metallic  properties. 


260  EARTHS. 

these  four  earths  constitute  the  great  mass  of  our  mountains,  rocks, 
stones,  gravel,  and  soil,  and  yere  the  five  others  annihilated,  it  would 
not  sensibly  diminish  the  volume  of  the  crust  of  the  globe.  Baryta 
and  strontia  exist,  however,  in  some  quantity,  and  baryta,  especially 
combined  with  sulphuric  acid,  is  of  frequent  occurrence,  although  it 
is  generally  confined  to  veins  in  the  rocks. 

As  chemical  reagents,  lime  and  baryta  are  of  signal  utility ;  stron- 
tia possesses  similar  properties,  but  has,  in  comparison  with  those 
earths,  little  that  is  peculiar,  or  that  gives  it  a  ground  of  preference. 
Silica,  alumina,  and  magnesia  are  of  limited  use  in  scientific  chem- 
istry, but  they  are  of  vast  importance  in  the  arts,  and  along  with 
lime,  are  the  foundation  of  the  vegetable  kingdom,  and  of  agricul- 
ture ;  as  our  best  soils  consist  of  different  proportions  of  these  earths  ; 
and  the  varying  qualities  of  soils,  although  modified  in  an  important 
degree  by  moisture  and  by  animal  and  vegetable  matter,  and  other 
causes,  are  characterized  chiefly  by  the  predominant  earths. 

The  preceding  sketch  has  been  presented,  that  the  student  might 
not  fail  to  obtain  a  just  idea  of  the  important  natural  order  of  earths, 
which  it  is  difficult  to  define  by  unexceptionable  chemical  characters  ; 
but  there  is  no  difficulty  in  giving  clear  discriminations,  provided  we 
divide  the  earths  into  groups.* 

The  divisions  under  which  the  earths  will  be  described,  are — 

1.  Alkaline  earths. 

2.  One  earth  of  a  sub-alkaline  character. 

3.  Earths  proper. 

ALKALINE    EARTHS. 

LIME BARYTES STRONTIA. THEIR    GENERAL    CHARACTERS. 

(a.)  Soluble  in  water,  but  much  less  so  than  the  alkalies. 

(b.)  Acrid  and  caustic ;  in  light  powder,  irritate  the  nostrils,  and 
produce  sneezing. 

(c.)  Test  colors  affected  by  them,  as  by  the  alkalies. 

(d.)  Differ  from  the  alkalies  in  their  very  difficult  fusibility,  but  fu- 
sible by  the  compound  blowpipe,  and  by  galvanism. 

*  Perhaps  the  only  characters  that  will  strictly  apply  to  them  all,  are  these— 
1.  They  are,  when  prepared  pure  by  art,  white  powders. — 2.  They  are  not  volatile 
by  heat,  and  are  remarkably  difficult  to  melt,  and  are,  both  when  pure,  and  when  in 
combination  with  each  other,  in  the  stones  and  rocks,  the  most  infusible  and  unalter- 
able bodies  that  are  generally  known  to  mankind. — 3.  They  have  oxygen  for  a  com- 
mon principle,  united,  in  each  earth,  to  a  peculiar  metallic  or  combustible  base.  It 
is  true  (as  suggested  by  a  friend,)  that  some  of  the  proper  metallic  oxides,  would  be 
covered  by  these  characters,  e.  g.  the  oxides  of  columbium,  titanium  and  cerium; 
but  still,  most  of  our  artificial  divisions,  fail  of  rigorous  exactness;  the  oxides  them- 
selves graduate  into  the  acids,  but  no  one  for  that  reason  thinks,  of  blending  them. 
There  can  be  no  good  objection  to  dividing  the  numerous  class  of  oxides  into  con- 
venient orders,  which  are  also  in  a  great  measure  natural.  See  Introduction,  p.  3. 


EARTHS.  261 

(e.)  Not  volatile  by  any  heat  hitherto  applied. 
tf.)  Form  soaps  with  oils. 

(g.)  In  common  with  the  other  earths,  combine  with  acids  and 
form  salts.* 

EARTH    OF    A    MIXED    CHARACTER. NAMELY,    MAGNESIA. 

a.}  Not  acrid  or  caustic. 

b.)  Applied  in  substance,  affects  the  vegetable  colors. 

c.)  Nearly  insoluble  in  water,  but  absorbs  it. 

d.)  Equally  difficult  to  fuse  as  lime,  not  volatile. 

e.)  Combines  readily  with  acids  to  form  salts. 

/.)  Combines  indirectly  with  oils  to  form  soap. 

EARTHS    PROPER. SILICA ALUMINA— GLUCINA ZIRCONIA — » 

YTTRIA.f 

Destitute  of  alkaline  properties,  except  that 

(«.)  They  unite  with  acids,  and  form  salts ;  silica  combines  per- 
manently with  only  one  acid  ;  i.  e.  the  fluoric. 

b.)  Insoluble  in  water  ;  but  most  of  them  absorb  it, 
c.)  Tasteless,  innoxious,  inodorous. 
d.)  No  effect  on  test  colors. 

e.)  Very  difficult  to  melt,  but  less  so  than  the  alkaline  earths  $ 
still  the  alkaline  earths  are  powerful  fluxes  of  the  earths  proper,  and 
of  common  metallic  oxides. 
(/.)  Not  volatile  by  heat. 
(g.)  In  their  pure  state,  do  not  combine  with  oils  to  form  soap. 

SEC.  I. — LIME. 

1.  DISCOVERY. — Familiarly  known  from  the  remotest  ages. 

2.  PREPARATION. 

(a.)  By  thoroughly  igniting,  in  a  good  furnace,  in  a  covered  crU" 
cible,  small  fragments  of  marble,  chalk,  J  or  shells,  or  other  pure  cal- 
careous carbonate  of  lime,  (Carrara  and  Parian  marble  are  prefer- 
red,) these  substances  lose  half  their  weight  or  more  in  the  form 
of  gas  and  water,  and  if  fully  calcined,  they  will  not  effervesce  with 
acids. 

(b.)  As  the  natural  carbonates  of  lime  are  not  always  pure,  we 
may  dissolve  them  in  dilute  muriatic  acid ;  then  add  ammonia,  which 


*  Even  silica  combines  permanently  with  fluoric  acid,  and  transiently  and  slightly 
with  some  other  acids ;  this  earth  differs  in  several  respects  from  the  rest,  and  some 
have  even  regarded  it  as  an  acid. 

t  It  is  scarcely  necessary  to  remark  that  Thorina,  which  was  transiently  admit- 
ted among  the  earths,  has  been  found  to  be  a  sub-phosphate  of  Yttria. 

t  Chalk  is  the  least  pure  of  the  three. 


EARTHS. 

will  precipitate  the  magnesia  and  alumina,  and  not  the  lime  ;  we  then 
decompose  the  filtered  solution  by  carbonate  of  potash,  and  the  pre- 
cipitated carbonate  of  lime,  after  being  washed  and  dried,  is  decom- 
posed by  a  strong  heat.  Common  good  quick  lime,  that  has  not 
been  air  slacked,  answers  every  purpose  for  demonstrating  the  pro- 
perties of  lime. 

3.  PROPERTIES. 

(a.)  Color,  white,  and  the  masses  recently  from  the  furnace  are 
rather  hard,  but  brittle.  When  dry,  not  active  on  the  animal  organs, 
but  if  moistened,  lime  acts  as  a  caustic ;  taste  astringent  and  alkaline. 

(6.)  Specific  gravity  2.3. 

(c.)  Soluble  in  water:  writers  vary  in  stating  the  proportion,  be- 
tween 450  and  778  parts  of  water  for  the  solution  of  1  part  of  lime, 
or  558  for  the  hydrate :  500  is  the  number  heretofore  adopted ;  pro- 
bably 700  may  be  near  the  truth ;  but  it  appears  that  only  a  weak 
lime  water  is  obtained  by  using  water  at  212°,  which  dissolves  only 
TTTTF  °f  ^e  Hme»  ana"  ¥JT  °f  the  hydrate,  while  at  32°.  Accor- 
ding to  Mr.  Dalton*  and  Mr.  R.  Phillips,  it  takes  up  ¥i^,  or  nearly 
double,  and  when  the  solution  is  heated,  it  becomes  troubled,  and 
lime  is  deposited.  These  facts  are  not  in  accordance  with  the  gen- 
eral laws  of  solution  when  it  is  aided  by  heat. 

(c?.)  Lime  water:  its  taste  is  acrid  and  disagreeable,  and  it  produ- 
ces upon  test  colors  the  effects  of  alkalies ;  it  is  not  however  caustic, 
and  there  is  so  little  of  it  contained  in  the  water  that  it  may  be  swal- 
lowed with  safety,  and  often  with  advantage.  It  is  a  valuable  reagent 
and  medicine  ;  it  is  prepared  by  simple  solution  of  lime,  in  wrater ;  it 
must  be  preserved  in  close  bottles  from  the  atmosphere, •}•  otherwise 
it  precipitates  as  a  carbonate. 

(e.)  Lime  water^  is  made  to  afford  crystals,  if  placed  in  a  vacu- 
um, under  the  receiver  of  an  air  pump,  the  evaporation  being  aided 
by  sulphuric  acid,  contained  in  another  vessel;  the  process  is  gradual, 
and  depends  on  the  same  principle  as  the  congelation  of  water  by 
the  same  means,  (see  page  116.)  The  crystals  are  transparent 
hexahedra,  and  are  true  hydrates,  containing  lime,  76.26,  water, 
23.74=100.00.J  Lime  water  forms  an  imperfect  soap  with  oil. 


*  Ann.  Phil.  N.  S.  I.  107. 

t  Place  in  a  clean  carboy,  a  quantity  of  good  hydrate  of  lime  ;  fill  the  vessel  with 
rain  water ;  agitate  it,  and  allow  the  lime  to  subside  over  night ;  it  will  be  dissolved 
in  one  fourth  of  an  hour,  and  in  the  morning  it  may  be  drawn  off  clear  by  a  syphon, 
or  filtered  through  paper  if  it  is  wanted  immediately ;  if  the  cork  be  good,  and  the 
water  is  not  allowed  to  freeze,  the  same  arrangement,  adding  water  from  time  to 
time,  will  answer  for  years. 

t  Ann.  de  Chim.  et  de  Phys.  I.  335. 


EARTHS.  263 

(/.)  Slacking  of  lime. — In  this  familiar  process,  the  earth  com- 
bines with  about  one  third  of  its  weight  of  water,  forming  a  true  hy- 
drate ;  and  in  this  condition,  lime  kept  secluded  from  the  air,  is  in  the 
most  useful  state  for  the  laboratory.  The  water  may  be  again  expel- 
led by  a  red  heat,  contrary  to  the  fact  in  the  case  of  the  hydrates  of 
potassa  and  soda,  and  of  baryta  and  strontia.  The  heat,  (about  800°, 
Dalton,)  arises  from  the  solidification  of  the  water,  and  is  much  more 
than  the  latent  heat  of  the  water,  because  ice  or  snow  and  lime  slack, 
with  energy,  and  give  out  a  heat  of  212°.  Light  sometimes  appears, 
when  the  slacking  is  performed  in  a  dark  place  ;  I  have  seen  it  from 
the  Carrara  marble.*  If  fragments  of  good  lime  be  placed  in  a  quart 
tumbler,  filling  not  more  than  one  third  of  it,  the  tumbler  resting  in 
a  dish,  the  proper  quantity  of  water  being  sprinkled  over  it,  and  a  tall 
bell  glass  covering  the  whole,  the  vapor  will  rise  in  a  dense  cloud ; 
it  will  soon  produce  currents  like  rain,  down  the  sides  of  the  bell,  which 
will  become  clear,  as  soon  as  it  attains  the  boiling  heat,  and  the  steam 
will  then  blow  out  powerfully  under  its  sides:  when  the  bell  is  lifted 
out  of  the  dish,  the  cold  air  will  again  produce  a  thick  cloud. 

(g.)  Milk  or  cream  of  lime,  is  the  hydrate  brought  to  the  consist- 
ence of  paste  with  water,  and  thus  mechanically  suspended  :  it  is 
very  useful  in  purifying  gases  from  carbonic  acid ;  they  are,  for  this 
purpose,  made  to  pass  through  the  milk  of  lime,  the  large  quantity 
of  the  earth  being  much  more  effectual  than  lime  water,  which  is  how- 
ever, very  convenient  in  small  experiments. 

(A.)  Lime  is  mechanically  raised  in  slacking,  as  is  perceived  by 
the  odor,  and  by  the  effect  on  test  paper,  placed  in  the  steam  that  ri- 
ses from  it. 

(i.)  Lime  absorbs  moisture  from  the  air,  falls  to  powder,  and  be- 
comes a  true  hydrate,  f 

(/.)  The  mere  water-slacking  of  lime  does  not  destroy  its  activity  ; 
its  peculiar  powers  are  blunted  or  suspended  by  air-slacking,  the  cause 
of  which  will  be  explained  under  the  history  of  the  carbonate. 

4.  FUSIBILITY. — Extremely  infusible;  first  partially  melted  by 
Dr.  Hare's  compound  blowpipe,  in  Philadelphia,  and  in  1812  more 
perfectly,  in  the  laboratory  of  Yale  College.  J  The  lime  must  be 
shaped  into  the  form  of  an  acute  cone,  not  over  the  size  of  a  large 
pin,  and  the  focus  of  heat  must  be  directed  upon  the  apex ;  when  it 
softens,  subsides,  and  is  soon  covered  with  a  vitreous  glaze.  Fusible 
also  in  the  galvanic  current.  The  light  emitted  by  lime,  in  the  focus 
of  heat,  is  most  intense  ;  it  has  been  used  with  a  stream  of  oxygen  gas, 


*  Jn  a  dark  cellar,  in  JMr.  Acoum's  house,  in  London,  some  lime  of  Carrara  mar- 
ble, during  its  slacking,  showed  luminous  points  of  mild  white  light. 
1  It  also  absorbs  carbonic  acid,  and  loses  its  causticity. 
t  Afterwards  by  Sir  H.  Davy,  by  Galvanism. 


264  EARTHS. 

directed  through  the  flame  of  an  alcohol  lamp,  for  the  purpose  of 
producing  a  signal  light,  which  can  be  seen  at  a  great  distance. 

5.  POLARITY. — It  is  attracted  to  the  negative  pole  in  the  galvanic 
circuit,  and  is  therefore  electro-positive. 

6.  Combining  weight,  28,  as  will  be  seen  more  particularly  under 
calcium,  the  basis  of  lime. 

7.  PHARMACEUTICAL  PREPARATION. — This  is  the  same  that  has 
been  already  described  in  giving  the  process  for  quick  lime. 

CALCIUM. 

1.  DISCOVERY. — In   1808,  in   Sweden,  by  Prof.  Berzelius  and 
Dr.  Pontin ;  afterwards  obtained  by  Sir  H.  Davy  in  England.     The- 
nard  attributes  the  first  observation  to  Dr.  Seebeck. 

2.  PROCESS. 

(a.)  A  cup  or  capsule,  made  of  moistened  lime,  or  sulphate  of 
lime,  containing  a  globule  of  mercury,  is  placed  on  a  metallic  dish; 
the  negative  wire  of  the  galvanic  battery  of  100  pairs,  in  good  action, 
is  made  to  touch  the  mercury,  and  the  positive  wire  is  brought  in 
contact  with  the  under  side  of  the  metallic  support.  An  amalgam  of 
mercury  and  calcium  is  formed,  but  the  process  must  be  continued 
a  good  while  in  order  to  obtain  any  manageable  quantity ;  in  a  small 
(green*)  glass  retort,  or  tube  closed  at  one  end,  this  amalgam  is  dis- 
tilled, with  naptha,  which  rises  first,  then  the  mercury,  and  the  cal- 
cium remains  in  an  atmosphere  of  vapor  of  naptha,  for  which  nitro- 
gen may  be  substituted. 

(b.)  When  potassium,  in  vapor,  was  passed  through  quick  lime 
heated  to  whiteness,  the  potassium  acquired  oxygen,  and  became 
potash,  and  a  dark  gray  substance,  with  metallic  lustre,  was  found 
imbedded  in  the  potash,  and  it  was  evidently  calcium,  more  or  less 
perfectly  reduced,  because  it  effervesced  violently  in  water,  and 
formed  a  solution  of  lime. 

3.  PEROXIDE. — This  is  formed  when  oxygen  gas  is  passed  over 
lime  ignited  in  a  tube ;  the  exact  proportions  are  not  known,  but  it  is 
supposed  to  contain  twice  as  much  oxygen  as  the  protoxide. 

In  the  moist  way,  the  oxygenized  water  of  Thenard  forms  the  same 
peroxide. 

4.  PROPERTIES. — Little  known. 

(a.)  Color,  white,  like  that  of  silver,  and  with  the  same  lustre  ; 
sinks  in  water. 

(b.)  Ignited  in  a  tube  in  which  the  distillation  of  the  amalgam  was 
going  on,  it  took  fire  when  the  tube  broke,  and  burnt  with  an  intense 


*  Because  white  glass  contains  oxide  of  lead,  whose  oxygen  would  change  the 
calcium  to  the  state  of  oxide,  or  lime. 


EARTHS.  265 

white  light,  into  quick  lime.  When  the  amalgam  of  calcium  was 
thrown  into  water,  hydrogen  gas  was  evolved,  and  lime  water  re- 
mained. 

(c.)  Lime  is  the  protoxide,  of  calcium.  Its  composition  is  estima- 
ted by  Berzelius  at  calcium,  71.73,  oxygen,  28.27  =  100.00. 

Thenard  says,  that  it  ought  to  contain  by  calculation,  39  of  oxygen. 

5.  ITS    EQUIVALENT  WEIGHT   is    stated   at  20,   and  therefore, 
oxygen  being  8*,  lime,  or  the  protoxide  is  represented  by  28. 

6.  POLARITY. — Electro  positive ;  it  goes  to  the  negative  pole  in 
the  galvanic  series. 

7.  USES  OF  LIME. — They  are  numerous  and  important.     In  med- 
icine, the  caustic  earth  is  not  used,  except  to  prepare  lime  water ; 
in  the  solid  form,  the  pure  earth  is  too  acrid  for  internal  use  ;  it 
was  formerly  used  as  an  escharotic,  and  its  caustic  properties  are  still 
employed  in  removing  the  hair  from   skins,  preparatory  to  tanning. 
It  is  almost  constantly  used  in  the  laboratory  ;  in  the  form  of  lime 
water,  it  is  an  important  reagent,  and  we  have  seen  that  it  is  employ- 
ed to  disengage  the  alkalies  in  a  caustic  state  ;  it  is  largely  used  for 
the  same  purpose  in  soap  making.     In  a  word,  it  is  of  great  value  in 
medicine,  in  architecture,  in  agriculture,  and  in  many  arts. 

Mortar  is  a  mixture  of  sand,  or  gravel,  or  both  and  lime ;  in  the 
proportions  of  fine  sand  3  parts,  coarse  sand  4,  quick  lime  1,  recent- 
ly slacked  with  as  little  water  as  possible. 

It  is  well  to  add  some  pulverized  lime,  that  has  not  been  slacked ; 
it  absorbs  water,  and  solidifies  the  other  ingredients.  Roman  mor- 
tar was  made  of  the  same  materials  as  the  modern,  but  of  the  best 
quality,  and  accurately  proportioned  ;  time  has  done  much  to  give  it 
hardness.  According  to  Pliny,  the  Romans  made  their  best  cement  a 
year  before  it  was  used,  so  that  it  was  partly  combined  with  carbonic 
acid  before  it  was  laid  in  the  work.  In  old  Roman  stone  buildings, 
the  stone  will  often  break  as  soon  as  the  mortar. 

Another  recipe  for  mortar. — Fine  sand,  3,  brick  powder,  3,  (well 
baked,)  slacked  lime,  2,  unslacked  lime  2.  If  very  little  water  be 
used,  the  mortar  sets  the  sooner.  Burnt  bones,  not  exceeding  one 
fourth  part,  improve  the  tenacity  of  mortar. 

Manganese  and  puzzolana  cause  mortal-  to  harden  beneath  the 
water.  Puzzolana  is  decomposed  lava,  and  consists  of  silica,  alu- 
mina, and  oxide  of  iron.  The  mortar  for  the  Eddystone  light-house 
on  the  S.  W.  coast  of 'Cornwall,  (Eng.)  was  composed  of  equal  parts 
of  slacked  lime  and  puzzolana. 


For  71.73  :  28.27  :  :  100  :  39.4  and  39.4  :  100  :  :  8  :  20.3.— Henry. 

34 


266        '  EARTHS. 

Manganesian  and  ferruginous  limestones  are  valuable  in  this  respect, 
and  a  portion  of  silica  and  alumine  in  the  composition  of  the  lime- 
stone improves  it  for  these  purposes.* 

Recipe  for  water  mortar. f — Blue,  clay,  4  parts,  manganese,  6, 
limestone  90,  and  all  in  powder  ;  calcine,  mix  with  sand  60  parts,  and 
form  it  into  a  mortar,  with  water.  The  tarras,J  used  for  the  con- 
struction of  dykes  in  Holland,  is  merely  an  ancient  decomposed  lava 
from  the  extinct  volcanos  on  the  Rhine  ;  some  call  it  a  decomposed 
basalt,  and  it  is  certain  that  the  rocks  of  this  family,  are  effectual  in 
this  way,  if  previously  decomposed,  or  calcined,  so  that  they  can  be 
broken  down  and  intimately  mixed  with  the  lime.§  Parker's  ce- 
ment is  composed  of  silica,  22,  alumine,  9,  oxide  of  iron  and  manga- 
nese, 13,  carbonate  of  lime,  55  =  99,  and  there  was  in  the  analysis  a 
loss  of  3.25.  The  white  cement  used  in  New  Haven  to  cover  stone 
houses,  is  composed  of  the  best  slacked  lime,  1  part,  by  measure, 
and  from  3  to  5  measures  of  coarse  siliceous  sand  and  some  hair, 
well  beaten  together,  and  laid  on  with  a  trowel ;  the  workmen  pre- 
tend to  add  sugar,  and  various  salts,  particularly  the  sulphate  of  pot- 
ash ;  but  having  tried  the  mortar,  both  with  and  without  these  addi- 
tions, I  am  persuaded  that  they  are  of  no  importance,  and  that  the 
cement  of  coarse  sand,  hair  and  lime,  alone,  will  stand  any  length  of 
time,  provided  water  does  not  get  beneath  ;  if  it  does,  the  first  freez- 
ing will  crack  the  mortar,  and  throw  it  off. 

Lime  is  of  great  use  in  Agriculture. — In  the  form  of  carbonate  of 
lime,  it  is  often  mixed  with  soils,  and  will  be  mentioned  again.  In 
the  state  of  quick  lime  it  is  largely  used  in  England,  where  it  is  com- 
mon to  see  extensive  tracts  covered  with  heaps  of  it.  ||  It  appears 
to  be  a  part  of  the  food  of  plants,  as  it  is  found  in  the  ashes  of  most  of 
them,  and  it  may  be  also  a  stimulus  to  vegetable  life.  Its  immedi- 
ate action,  when  caustic,  is  to  destroy  vegetable  organization,  and  it 
appears  to  act  as  a  manure,  principally  by  decomposing  hard  dry 

*  Hydraulic  lime  of  the  state  of  New  York,  contains  according  to  Dr.  Hadley's 
analysis,  carbonic  acid  35.05,  lime  25,  silex  15.05,  alumine  16.05,  water  5.03,  oxide 
of  iron  2.02.— Am.  Jour.  Vol.  Ill,  p.  231. 

t  Hydraulic  lime  is  found  at  Southington,  Connecticut,  near  the  canal,  and  in 
many  places  on  the  Erie  Canal. — See  Am.  Jour.  Vol  Xlll,  p.  382. 

i  The  proportions  said  to  be  used  in  Holland,  are  tarras  1  part,  and  slacked  lime  2 
parts. 

§  I  saw  them  preparing  the  trap  rocks  in  this  manner,  at  Greenock,  where  (1806,) 
they  were  making  hydraulic  mortar  for  a  dock.  The  porous  and  vesicular  trap 
which  they  used  was  from  the  neighboring  isle  of  Arran.  That  in  East  Haven, 
which  is  crumbly,  and  used  for  mending  the  roads,  and  the  vesicular  trap  near 
Hartford,  (see  Am.  Jour.  Vol.  XV 11,  No.  1,)  would  in  all  probability  answer  the 
same  purpose,  and  it  may  be  found  of  the  same  character  in  many  other  places  in 
our  trap  regions.  Th«  more  vesicular,  and  the  more  decomposed  it  is,  the  better, 
because  it  is  the  more  easily  pulverized  by  calcination  and  grinding. 

I)  Extensively  used  in  Pennsylvania,  and  highly  valued.— J.  G.  Not  much  used 
in  New  England. 


EARTHS.  267 

vegetable  fibres,  and  thus  rendering  them  soluble  ;  even  tanner's  bark 
is  decomposed  by  lime,  and  rendered  useful  as  a  manure  ;  it  is  thought 
to  be  injurious  with  animal  manures,  unless  they  are  too  rich,  and 
need  to  be  in  part  decomposed.* 

SEC.  II.  BARYTA. 

Name  from  the  Greek  /3apu£,  heavy. f 

1.  DISCOVERY. — By  Scheele,  in   Sweden,  in    1774;  formerly 
confounded  with  lime. 

2.  PROCESS. 

(a.)  Native,  or  artificial  carbonate,  in  powder,  mixed  with  lamp- 
black and  oil,  in  a  ball,  is  strongly  calcined  in  a  crucible,  for  one 
hour,  by  the  heat  of  a  forge  or  wind  furnace,  and  the  carbonic  acid 
is  thus  decomposed,  or  expelled.  Boiling  water  dissolves  out  the 
caustic  earth.  The  theory  of  the  process  will  be  rendered  more  in- 
telligible hereafter. 

(b.)  By  calcination  of  the  nitrate  of  Barytes  ;  see  that  salt. 

3.  PROPERTIES. 

(a.)  Color,  gray  before  slacking;  consistency,  porous  ;  after  slack- 
ing, a  white  powder  ;  sp.  gr.  4. 

(b.)  Taste  acrid  and  caustic ;  poisonous. 

(c.)  Affects  the  test  colors,  as  lime  and  the  alkalies  do. 

(d.)  The  hydrate  is  fusible  in  its  own  water,  of  which  it  contains 
about  9  or  10  per  cent. 

(e.)  Baryta,  even  when  obtained  from  the  nitrate,  is  fusible  by  the 
compound  blowpipe.f 

(f.)  Water  causes  it  to  slack  with  much  greater  energy  than 
lime  ;  the  phenomena  and  theory  are  the  same,  but  much  more  strik- 
ing, and  light  is  said  to  be  sometimes  emitted. §  The  water  slacked 
baryta,  is  a  true  hydrate,  and  as  the  earth  is  represented  by  78,  and 
there  is  one  proportion  of  water  in  the  hydrate,  the  equivalent  num- 
ber is  of  course  87. 

It  slacks  in  the  air,  as  lime  does,  and  for  the  same  reason. 
It  dissolves  readily  in  20  parts  of  water  at  60°,  and  if  boil- 
ing, in  2  parts. 

(i.)  On  cooling,  it  forms  regular  crystals — flattened  hexagonal 
prisms. 


*a  13  vi 

if:} 


*  See  Davy's  Agricultural  Chemistry,  and  Ure's  Diet. 

t  The  natural  sulphate  is  known  to  the  miners,  by  the  name  of  heavy  spar. 

t  Respectable  authors  state  that  baryta  thus  prepared  is  infusible,  but  they 
had  probably  not  tried  the  compound  blow-pipe. 

§  The  observation  is  attributed  to  Dobereiner,  and  it  will  not  appear  very  extraor- 
dinary, since  lime  sometimes  exhibits  light  while  slacking,  although  the  energy  of 
the  action  is  much  less  remarkable. 


268  EARTHS. 

i/.)  They  contain,  according  to  Dalton,  70  per  cent,  of  water, 
lose  50  by  ignition  ;  their  constitution  is,  according  to  the  same 
author,  baryta  1  proportion  78,  and  water  20  proportions  or  180,  and 
their  equivalent  number  is  258  ;  they  melt  in  their  own  water,  or  suffer 
the  aqueous  fusion ;  after  ignition,  the  dry  powder  which  remains, 
slacks  again  with  great  energy. 

(k.)  Crystals  soluble  in  17J  times  their  weight  of  water. 

(/.)  Burning  alcohol,  although  it  does  not  dissolve  this  earth,  re- 
ceives from  the  crystals  a  yellow  tinge,  but  this  is  better  exhibited  in 
the  flame  of  the  compound  blowpipe,  in  the  focus  of  which,  every 
form  of  baryta,  not  excepting  the  sulphate,  exhibits  this  characteristic 
color  in  the  most  striking  manner. 

(m.)  Barytic  water  is  a  very  useful  reagent ;  it  should  be  kept 
stopped  from  the  air,  otherwise  it  is  precipitated  in  the  form  of  an  in- 
soluble carbonate.  It  produces  all  the  effects  of  the  alkalies  upon  the 
test  colors. 

(n.)  Solution  of  baryta  forms  a  soap  ivith  oils  ;  its  salts  also  form 
soaps  if  mingled  with  aqueous  solutions  of  alkaline  soaps. 

(0.)  Dust  of  the  earth  irritates  the  nostrils  as  it  rises. 

4.  POLARITY — electro-positive,  it  resorts  to  the  negative  pole  of 
the  galvanic  battery. 

5.  COMBINING  WEIGHT,  78,  the  elements  of  which  may  be  seen 
under  barium. 

BARIUM. 

1 .  Obtained  in  the  same  manner  as  calcium,  using  native  carbonate 
of  baryta  or  the  pure  earth,*  made  into  a  paste  with  water,  a  globule 
of  mercury  being  placed  in  a  little  hollow  made  in  its  surface ;  the 
paste  was  laid  upon  a  platinum  tray  in  connexion  with  the  positive 
wire  of  a  galvanic  battery,  while  the  negative  wire  touched  the  mer- 
cury.    The  mercury  is  distilled  off  in  the  same  manner,  but  it  is  very 
difficult  to  obtain  the  metal,  f 

2.  PROPERTIES. 

(a.}  Metal  of  a  dark  grey  color,'^  with  less  lustre  than  cast  iron. 
(b.)  Solid  at  the  ordinary  temperature,  but  becomes  fluid  below 
ignition. 

(c.)  Near  redness,  rises  in  vapor,  and  acts  violently  on  the  glass. 


*  Oxide  of  mercury  may  be  used  in  obtaining  the  metals  of  the  earths;  one  third 
partis  mixed  with  two  thirds  of  the  earth,  and  galvanized,  when  an  amalgam  is 
formed  with  the  metallic  base. 

t  Dr.  Clarke  states  that  he  obtained  the  metal  from  the  nitrate,  by  the  compound 
blowpipe.  I  mentioned  in  the  memoir  published  in  Bruce's  Journal,  in  1812,  that 
the  metallic  bases  of  both  baryta  and  strontia,  appeared  to  me  to  be  evolved,  and  to 
dart  out  in  bright  scintillations,  when  the  earths  were  in  the  focus  of  the  instrument, 
but  as  they  always  burned  away,  I  was  notable  to  collect  the  metals. 

t  "  White  color,  with  metallic  liK-fie,  having  a  resemblance  to  silver.". — Murray. 


EARTHS.  269 

(d.)  In  air,  becomes  covered  with  a  film  of  baryta,  and  in  water  un- 
dergoes the  same  change;  effervesces  violently  and  evolves  hydro- 
gen. If  gently  heated  in  air,  it  burns  with  a  deep  red  light  and  be- 
comes baryta. 

(e.)  Sinks  in  water,  and  even  in  sulphuric  acid,  although  surround- 
ed by  gas ;  hence  its  sp.  gr.  cannot  be  less  than  2,  probably  over  3. 

(/.)  Flattened  with  difficulty  by  pressure. 

(g.)  Constitution  of  the  protoxide,  about  89.75,  metal,  10.25 
oxygen=100.00.  Barium,  1  proportion,  70,  oxygen,  1  proportion, 
8=78. 

(h.)  PEROXIDE  OR  DETJTOXIDE. — Baryta,  prepared  by  ignition  of 
the  nitrate,  is  placed  in  fragments  as  large  as  a  hazel  nut,  in  a  coated 
glass  tube,  and  heated  to  low  redness,  when  it  rapidly  absorbs  dry 
oxygen  gas  as  it  is  passed  over  it  and  becomes  peroxide  with  prob- 
ably two  proportions  of  oxygen  ;  it  is  formed  also  by  heating  ba- 
ryta in  contact  with  oxygen  or  common  air  resting  upon  it,  but  in  the 
latter  case  some  carbonate  is  also  formed.  Concentrated  barytic 
water  becomes  filled  with  pearly  plates  of  the  deutoxide  of  barium, 
when  oxygenized  water,  containing  ten  or  twelve  times  its  volume  of 
oxygen  is  poured  into  it. — Thenard. 

Composition  of  the  peroxide. — Barium,  70,  oxygen,  2  proportions, 
16  =  86;  the  peroxide  contains  twice  as  much  oxygen  as  the  pro- 
toxide. 

It  has  been  found  that  the  nitrate  of  baryta  may  be  decomposed 
by  heat  with  such  care,  that  the  deutoxide  is  left ;  it  is  done  in  a  lu- 
ted porcelain  retort,  connected  by  a  Welter's  safety  tube  with  an  in- 
verted jar  of  water.  The  heat  is  gradually  raised  to  redness,  as  long 
as  nitric  oxide  or  nitrogen  gas  is  disengaged,  and  when  they  cease 
and  pure  oxygen  comes,  it  is  a  proof  that  all  the  nitrate  is  decompos- 
ed, and  then  the  deutoxide  will  remain  in  the  retort. — Turner. 

(i.)  The  deutoxide  of  barium  is  scarcely  sapid,  it  is  grayish  white, 
loses  its  excess  of  oxygen  by  an  intense  heat,  and  acts  with  the  aid 
of  the  same  agent  upon  various  combustible  bodies,  and  thus  becomes 
a  protoxide.  In  contact  with  hydrogen  near  a  red  heat,  there  are 
luminous  jets  from  the  surface  of  the  deutoxide,  but  the  water  that 
is  formed  is  all  retained  in  the  state  of  hydrate,  and  the  baryta  thus 
becomes  very  fusible.  Boiling  water  causes  the  excess  of  oxygen 
to  escape  in  the  form  of  gas. 

(/.)  This  substance  was  employed,  (July,  1818,)  by  Thenard,  for 
the  oxygenation  of  water.* 

Baryta  is  poisonous  ;  its  natural  carbonate  is  employed  in  Lan- 
cashire, (Eng.)  as  a  ratsbane. 


*  See  this  work,  p.  215,  and  Henry,  Vol.  I,  p.  264,  10th  Lond.  Ed. ;  also,  Ann.  dc 
Chim.  et  de  Phys.  VII.  IX  ;  Ann.  of  Philos.  XIII,  XIV,  XV,  and  Quarterly  Eng. 
Jour,  of  Science,  VI.  150,  379,  VIII.  114,  154. 


270  EARTHS. 

Pure  baryta  is  useful  to  the  chemist  as  a  test,  particularly  for  the 
discovery  of  carbonic  acid,  either  free  or  combined.  Its  muriate  is 
used  by  physicians  in  scrofula,  &ic.  The  sulphate  is  the  most  abund- 
ant form,  and  it  is  convertible  into  every  other,  by  certain  processes 
which  will  be  mentioned  in  their  proper  place. 

3.  POLARITY — Electro-positive  ;  it  resorts  to  the  negative  pole  in 
the  galvanic  circuit. 

4.  COMBINING  WEIGHT,  70. — This  is  the  number  of  Dr.  Thom- 
son.    Berzelius  states  it  at  50.66,  but  the  former  number  is  gene- 
rally adopted. 

SEC.  III. — STRONTIA. 

1.  NAME. — From  the  lead  mine  of  Strontian,  in  Argyleshire  in 
Scotland,  whence  the  minerals  containing  it  were  first  brought. 

2.  DISCOVERY. — By  Dr.  Thomas  Hope,*  then  and  still,  professor 
of  chemistry  in  the  Univ.  Edin.  Anno.   1791. 

3.  PREPARATION. — The  same  as  that  of  baryta. f 

4.  PROPERTIES. 

(a.)  The  result  of  the  igneous  decomposition  of  the  nitrate  is  a 
grayish  porous  substance  ;  sp.  gr.  approaching  that  of  baryta. 

(b.)  With  water,  slacks  violently,  like  baryta  and  lime,  and  the 
theory  is  the  same ;  the  powder  of  the  dry  substance  irritates  the 
nostrils  and  lungs. 

(c.)  After  slacking,  no  more  water  being  used  than  is  necessary, 
the  earth  remains  in  the  form  of  white  powder  ;  it  is  then  a  hydrate 
consisting  of  strontia,  one  proportion,  52,  and  one  of  water  9=61. 
The  hydrate  fuses  readily  at  ignition,  but  is  not  decomposed  by  the 
strongest  heat  of  a  wind  furnace. 

(d.)  More  water  being  added,  it  dissolves  in  about  40  parts ;  if 
the  water  be  boiling  hot,  it  dissolves  in  20  parts  of  that  fluid,  and  crys- 
tals are  formed  on  cooling,  having  the  form  of  thin  quadrangular 
plates,  sometimes  square,  oftener  parallelograms,  not  over  J  of  an 
inch  in  diameter.J 

(e.)  After  being  heated,  the  dry  earth  remaining,  is  about  32  per 
cent. ;  the  crystals  contain  1  proportion  of  earth,  52,  and  12  of  wa- 
ter, 108=160. 

(/.)  At  60°,  soluble  in  51 J  parts  of  water ;  boiling  water  takes  up 
half  its  weight. 


*  Dr.  Crawford  observed  a  difference  between  the  muriate  of  strontia  and  that  of 
baryta,  in  1790.  Klaproth  confirmed  the  views  of  Dr.  Hope. 

t  Vide  Edin.  Trans.  IV,  44. 

t  In  both  cases,  the  decomposition  of  the  sulphate  is  the  cheapest  process ;  see  the 
articles  sulphate  of  baryta  and  sulphate  of  strontia.  The  carbonate  is  managed 
with  the  greatest  ease. 


EARTHS.  271 

The  composition  of  the  hydrate  of  strontia  according  to  Dalton,  is 
1  proportion  of  earth  and  12  of  water. 

(g.)  Strontia  imparts  to  the  flame  of  boiling  alcohol,  a  blood  red 
color  ;  its  effects  on  the  test  colors  are  the  same  as  those  of  baryta, 
lime,  &ic. 

!h.)  No  union  with  fixed  alkalies  or  baryta. 
i.)  Heat  readily  separates  the  water  from  the  hydrate,  and  from 
the  crystals. 

( /.)  The  compound  blowpipe  melts  the  earth  itself,*  with  the  char- 
acteristic red  flame. 

(k.)  This  blowpipe  produces  a  similar  flame  from  every  combination 
of  strontia,  even  from  the  native  minerals. 

(L.)  DISTINCTIVE  CHARACTERS — cannot  be  confounded  with  any 
thing  except  baryta,  but  it  is  lighter  than  that  earth,  less  caustic,  and 
attracts  acids  less  powerfully  ;  the  strontitic  salts  being  decomposed 
by  baryta,  produce  different  combinations  with  acids,  are  less  poison- 
ous, and  give  a  different  colored  flame. 

5.  POLARITY. — Like  that  of  baryta,  electro-positive,  and  of  course 
it  is  attracted  to  the  negative  pole  in  the  galvanic  series. 

6.  COMBINING  WEIGHT,  52 — composed  of  strontium  one  propor- 
tion, 44,  and  oxygen  one,  8  =  52. 

STRONTIUM. 

1 .  Obtained  from  native  carbonate  of  strontia,  by  the  same  pro~ 
cesses  as  those  which  afford  barium;  discovered  by  Sir  H.  Davy,  in 
1808. 

2.  PROPERTIES. 

(a.)  Similar  to  those  of  barium ;  has  less  lustre ;  difficult  to 
fuse ;  not  volatile. 

(b.)  Action  of  air  and  of  water,  converts  it  into  strontia;  in  wa- 
ter, it  produces  hydrogen  gas. 

(c.)  Proportions  of  the  constituents  of  the  protoxide. 

Strontium,  84.54,  or  1  equivalent,  44 

Oxygen,       -         -     15.46,  or  1  -       8 

100.00  52 

3.  THE  DEUTOXIDE  OR  PEROXIDE  of  strontium  is  obtained  in  pre- 
cisely the  same  manner  as  that  of  barium.     According  to  Thenard, 
(II,  314,)  it  is  best  obtained  by  the  action  of  the  oxygenized  water, 
or  deutoxide  of  hydrogen  upon  strontia  water;    the  peroxide    of 
strontium  precipitates  in  brilliant  pearly  crystals.     This  oxide,  by 


*  First  effected  by  Dr.  Hare,  1802—3.    See  Phil.  Trans,  of  Philad.    It  is  one  of 
the  most  refractory  of  natural  substances. 


272  EARTHS. 

heat,  even  that  of  a  lamp,  gives  up  its  excess  of  oxygen,  and  becomes 
protoxide.  It  acts  like  the  nitrates  upon  burning  coals,  causing  in- 
creased combustion.  When  it  is  moist,  it  gradually  loses  the  oxygen, 
and  rapidly  in  hot  water.  It  appears  to  contain  just  twice  as  much 
oxygen  as  the  protoxide  or  strontia. 

4.  COMBINING  WEIGHT. — This  is  estimated  at  44. 

5.  POLARITY. — Electro-positive;  resorts  to  the  negative  pole  of 
the  galvanic  battery. 

6.  USES,  &tc. — Strontia  has  the  same  uses  in  chemistry  as  baryta. 
It  is  a  test  for  carbonic  and  sulphuric  acids  ;  as  a  natural  production, 
it  is  more  rare,  especially  its  carbonate ;  its  sulphate  is  found  abund- 
antly in  Put-in-Bay,  Lake  Erie ;  at  Detroit,  Mackinaw,  Lockport,  &c. 

The  salts  of  strontia  are  not  poisonous ;  the  pure  earth  is  acrimoni- 
ous like  the  other  alkaline  bodies. 

The  natural  and  artificial  compounds  of  baryta,  are  heavier  than 
those  of  strontia,  and  there  are  various  points  of  difference  found  in 
their  combinations.  The  nitrate  of  strontia  is  used  to  give  a  blood 
red  color  to  artificial  fire  works.* 

SEC.  IV. — MAGNESIA. 

1.  DISCOVERY. — In  the  beginning  of  the  eighteenth  century,  ex- 
posed for  sale  as  a  panacea  at  Rome,  by  a  canon,  who  called  it  pow- 
der of  Count  Palma  ;  but  Dr.  Black,  in  1755,  was  the  first  person 
who  distinguished  it  clearly  from  other  substances. 

2.  PREPARATION. 

(a.)  In  the  arts. — From  the  muriate  and  sulphate  of  magnesia, 
found  in  sea  and  saline  water ;  they  are  decomposed  by  alkalies,  or 
usually  by  their  carbonates ;  magnesia  may  be  extracted  by  acids  from 
magnesian  stones,  and  the  salts  thus  obtained  can  be  decomposed  as 
above. 

(&.)  In  Chemistry. — Ignite  the  common  carbonate  of  the  shops, 
or  dissolve  the  sulphate  and  decompose  it  by  any  alkali  or  alkaline 
carbonate,  wash  thoroughly,  and  ignite  the  precipitate. 

3.  PROPERTIES. 

(a.)  In  light  spongy  masses,  or  in  a  friable  powder,  which  forms 
with  water  a  paste  destitute  of  cohesion ;  the  carbonate  is  commonly 
seen  in  cubical  cakes. 

(b.)  Sp.gr.  2.3;  still  the  cakes  float  awhile  on  water,  till  they 
are  filled  by  absorption. 

(c.)  Taste  insipid,  or  slightly  earthy  ;  lime  mixed  with  it  some- 
times communicates  to  it  a  slight  degree  of  acrimony. 

(d.)  Mild,  harmless,  and  without  corrosive  action  on  the  living  or 
dead  animal  organs. 

*  Ure,  2d  Ed.  743. 


EARTHS.  273 

(e.)  Effects  the  most  delicate  test  fluids ;  if  mixed  with  them  in 
substance*  e. g.  cabbage  infusion,  violet  tincture,  and  that  of  tur- 
meric ;  but  it  is  not  sufficiently  soluble  in  water,  to  impart  the  same 
power  to  that  fluid. 

(/.)  Does  not  slack  ivith  water. 

(g.)  Nearly  insoluble  in  that  fluid,  which  takes  up  about  5TVj  at 
60°,  and  at  212°  ^i^.f 

(A.)  Absorbs  water,  so  that  100  becomes,  in  weight,  118;  heat 
drives  the  water  off,  and  the  magnesia  contracts  again.  It  forms  a 
hydrate  with  water,  but  it  unites  with  this  fluid  without  any  sensible 
heat,  and  it  is  easily  driven  off  at  ignition. 

(i.)  Precipitated  from  acids  in  the  state  of  hydrate  containing 
probably  one  third  water. 

(/.)  This  hydrate,  dried  by  a  very  gentle  heat,  is  transparent:  it  is 
supposed  to  contain  1  equivalent  of  magnesia  20,  and  1  of  water,  9=29. 

(k.)  Native  hydrate,  of  Hoboken,  New  Jersey,  contains  about  30 
per  cent,  of  water. 

(I.)  Alkalies  do  not  combine  with  magnesia ;  alkaline  earths  unite 
with  it  by  heat. 

(m.)  Of  very  difficult  fusion;  first  melted  by  Dr.  Hare's  blow* 
pipe,  in  the  laboratory  of  Yale  College.  J 

(ra.)  Those  minerals  in  which  it  is  a  large  ingredient,  are  very 
infusible  ;  hence  soapstone  is  used  in  furnaces. 

(0.)  With  lirne,  in  excess,  it  melts  in  furnaces ;  for  the  lime,  al- 
though itself  infusible,  acts  as  a  flux. 

4.  POLARITY. — Magnesia  goes  to  the  negative  pole,  and  is  there- 
fore electro- positive. 

5.  COMBINING  WEIGHT. — Theory  estimates  it  at  20 ;  of  which  12  is 
assigned  to  magnesium  and  8  to  oxygen,  being  1  proportion  of  each. 

6.  CHARACTERISTICS. — Its  sulphate  is  very  soluble,  while  those 
of  lime,  baryta  and  strontia,   are  very  insoluble  :  its  nitrate  and  mu- 
riate are  very  deliquescent,^  and  soluble  in  alcohol :  the  bi-carbonates 
of  potassa  and  soda  do  not  precipitate  it,  on  account  of  the  carbonic 
acid.  ||    Oxalate  of  ammonia,  which  readily  precipitates  lime,  does  not 
precipitate  magnesia,  if  the  solution  is  moderately  diluted. — Turner. 

7.  USES. — Magnesia  is  a  very  useful  article  of  the  materia  medica; 
it  is  used  as  an  antacid  and  cathartic.     It  seems  however  to  be  nearly 
inoperative,  unless  there  is  acid  in  the  stomach,  or  unless  acid  is 
taken  after  it:    all  the  salts  of  magnesia  are  bitter  and  cathartic. 


*  Probably  this  effect  is,  in  some  cases,  owing  to  the  fact,  that  the  alkali  used  in 
decomposing  the  raagnesian  salt  has  not  been  perfectly  removed  by  washing. 
t  Fyfe,  quoted  by  Henry. 
t  Con.  Acad.  Trans.  Am.  Jour.  Vol.  II,  p.  290. 
The  nitrate  of  lime  is  deliquescent. 
The  same  is  true,  in  a  good  degree,  of  liinc. 

35 


274  EARTHS. 

The  carbonate  is  most  commonly  used,  but  the  pure  earth,  sold  un- 
der the  name  of  calcined  magnesia,  is  sometimes  preferred,  because 
no  gas  is  extricated  from  it  in  the  stomach.  Magnesia  sometimes 
forms  large  and  dangerous  accumulations  in  the  bowels,  of  several 
pounds  weight,  particularly  when  its  use  has  been  long  persevered 
in,  and  the  earth  has  not  been  duly  evacuated,  by  acids,  forming 
with  it  saline  combinations.  It  sometimes  enters  into  the  clays,  and 
other  materials  which  go  to  form  porcelain,  in  the  fabrication  of 
which,  on  account  of  its  infusibility,  it  serves  a  valuable  purpose.  It 
is  one  of  the  four  earths  which  form  a  large  part  of  the  crust  of  this 
planet.  Soapstone  owes  its  peculiar  properties  to  magnesia,  particu- 
larly its  infusibility :  magnesian  stones,  such  as  soapstone  and  talc, 
are  much  employed,  not  only  to  resist  fire,  but  because  they  are  so 
easily  wrought  by  tools  into  any  desired  form.*  They  are  used  in 
building- 

MAGNESIUM. 

1 .  Obtained  in  the  same  way  as  the  other  metals  of  the  earths. 

2.  A  white  and  brilliant  solid  ;  (a  little  mercury  still  remaining  in 
combination  with  it.) 

3.  Sinks  rapidly  in  water,  although  surrounded  by  bubbles  of  gas. 

4.  Both  in  air  and  water  reproduces  magnesia ;   in  air  gains 
weight,  as  the  balance  proves,  both  with  respect  to  this  and  other 
earths. 

5.  POLARITY. — Magnesium  goes  to  the  negative  pole,  and  is  there- 
fore electro-positive. 

6.  The  combining  weight  is  estimated  by  Dr.  Thomson  at  12,  and 
this,  with  1  proportion  of  oxygen,  forms  magnesia,  which  is  the  only 
known  oxide  of  magnesium,   whose   equivalent  is  of  course,  26. 
There  can  be  no  doubt  that  magnesia  is  a  metallic  oxide.     Hitherto 
chemists  have  been  unable  to  make  it  absorb  more  oxygen. 

SEC.  V. — SILICA. 

1.  NAME. — Sttev  is  the  Latin  for  flinty  which  is  composed  of  this 
earth,  nearly  pure  ;  limpid  rock  crystal  is  almost  pure  silica,  and  sev- 
eral other  siliceous  minerals,  as  chalcedony,  carnelian,  opal,,  agate, 
&c.  consist  principally  of  this  earth.  The  purest  white  sand  contains 
little  else  :  in  the  form  of  quartz  it  constitutes  mountain  masses,  and 
ki  that  of  sandstone  vast  strata. 


*  Savage  nations  are  acquainted  with  these  uses :  many  of  their  containing  ves- 
sels, especially  vessels  for  cookery,  are  made  of  these  minerals.  After  the  abori4- 
gines  of  this  country  became  acquainted  with  the  Europeans,  they  made  bullet 
moulds  of  soapstone ;  they  were  ingeniously  arranged  in  halves,  with  a  regular  mouth , 
and  were  tied  together  by  withes ;  I  have  such  a  specimen.  Soap  stone  is  also  used 
fte diminish  friction  in  machinery. — Am*  Jour.  Vol.  XIV,  p.  376. 


EARTHS.  275 

2.  PREPARATION. 

(a.)Flint  or  rock  crystal,  ignited,  thrown  into  water,  and  pulver- 
ized, affords  silica  sufficiently  pure  for  every  common  purpose. 

(b.)  But  the  more  correct  process  is,  to  mix  these  powders  with  3 
or  4  parts  of  carbonate  of  potash  or  soda,*  and  to  melt  the  mixture 
in  a  crucible,  giving  a  higher  heat,  for  half  an  hour  or  an  hour,  to- 
wards the  last,  and  stirring  it  to  prevent  overflowing. f 

(c.)  Caustic  potash  or  soda  is,  of  course,  more  energetic  in  its  ac- 
tion, but  is  more  expensive ;  there  is  however  an  advantage  in  using 
caustic  alkali,  as  it  does  not  intumesce  ;  if  a  silver  crucible  is  used, 
it  should  be  thick,  that  there  may  be  the  less  danger  of  melting  it. 

(d.)  Dissolve  the  melted  alkalino-siliceous  mass  in  water,  filter, 
and  add  diluted  muriatic  or  sulphuric  acid  as  long  as  precipitation 
continues ;  the  acid  must  be  added  in  excess.  J 

(e.)  The  solution  was  formerly  called  liquor  silicum,  liquor  of 
flints;  the  vitreous  mass  from  which  it  is  obtained  is  deliquescent, 
and  if  the  solution  formed  from  it  is  dilute,  and  the  acid  is  added 
gradually,  the  alkali  may  be  saturated  without  precipitating  any  of  the 
silica,  but  by  evaporation  to  dryness  the  silica  is  rendered  insoluble  ; 
the  salt  formed  by  the  alkali  may  be  dissolved  out,  and  the  earth  thus 
obtained  pure  after  ignition. 

(/.)  If  the  proportions  of  alkali  and  earth  are  reversed,  then  the 
compound  produced  is  glass ;  of  which  mention  will  be  made  again. 

3.  PROPERTIES. 

White,  insipid,  harsh. 

•7V0  effect  on  test  colors,  no  causticity,  or  any  alkaline  proper- 
ty, except  its  union  with  a  single  acid,  the  fluoric. 

(c.)  Water  does  not  directly  dissolve  silica,  nor  is  it  absorbed  by 
that  earth,  but  when  it  is  newly  precipitated,  it  retains  26  per  cent, 
of  water,  at  70°  Fahr. 

(d.)  When  dry  it  is  insoluble  in  water,  but  when  just  precipita- 
ted, it  is  dissolved  by  that  fluid,  in  the  proportion  of  about  ToVT»$  an(^ 
and  if  taken  in  its  nascent  state,  ||  it  is  even  largely  dissolved,  and  a 

*  Dry  pearl  ashes  will  do. 

t  It  is  recommended  to  dissolve  the  alkali  first,  in  as  little  water  as  may  be,  to  mix 
it  with  the  silica,  evaporate  to  dryness,  and  then  fuse  it,  which  may  be  done  in  a 
silver  crucible.  From  my  own  experience,  I  should  however  recommend  caution 
in  the  use  of  silver  vessels,  as  they  melt  at  about  the  degree  of  heat  which  produ- 
ces the  combination  between  the  silica  and  the  fixed  alkali. 

t  Dr.  Henry  remarks,  "  the  alkaline  liquor  must  be  added  to  the  acid,  and  not  the 
reverse ;  for,  in  the  latter  case,  the  precipitate  will  be  glass  and  not  silica." — Vol.  I. 
p.  642,  Mh  ed. 

§  Found  naturally  dissolved,  as  in  the  Geysers  in  Iceland,  in  which  the  solution 
is  aided  by  soda,  contained  in  the  water:  in  the  similar  hot  fountains  of  the  Azores, 
silica  is  found  in  solution,  &c.  there  are  natural  hydrates,  and  the  immense  num- 
ber of  crystals  of  quartz,  evince  that  silex  has  been  in  solution  on  a  great  scale. 

||  Particularly  when  the  sulphuret  of  silicium  is  dissolved  in  water,  and  the  silica 
is  regenerated  by  the  oxygen  of  that  fluid,  while  its  hydrogen  is  evolved,  combined 
with  sulphur. 


276  EARTHS. 

bulky  gelatinous  hydrate  is  obtained,  by  a  gentle  evaporation  :  it  is 
decomposed  at  a  common  temperature,  but  entirely  at  ignition.  Dr. 
Thomson,*  has  shown  that  there  are  several  hydrates  of  silica. 

(e.)  Insoluble  in  acids,  except  the  fluoric,  which  attacks  it  with 
great  energy. 

(f.)  When  newly  precipitated,  soluble  to  some  extent,  in  several 
acids,  and  readily  forms  triple  salts.  Dr.  Marcet  recommends  to 
precipitate  it  with  muriate  of  ammonia. 


(g.)  Specific  gravity  2.66, 
(h.}    •"•"• 


Infusible  in  any  furnace,  but  readily  melted  by  the  compound 
blowpipe ;  this  was  done  originally  by  Lavoisier,  with  oxygen  gas 
directed  upon  burning  charcoal ;  afterwards,  and  often,  by  Dr.  Hare, 
and  in  the  laboratory  of  Yale  College  :f  it  forms  a  perfect  glass. 

(h.)  Silica,  minutely  divided,  is  dissolved  at  a  boiling  heat,  by  caus- 
tic fixed  alkali;  the  alkali  should  be  twice  the  weight  of  the  silica; 
after  evaporation,  the  white  puffy  mass  forms  a  clear  solution  with 
warm  water,  as  already  mentioned  under  (e.) 

(i.)  Silica  is  hard,  and  when  rubbed  between  two  plates  of  glass 
wears  them  so  as  to  spoil  their  polish. 

4.  POLARITY. — I  believe  it  is  not  distinctly  determined.     Several 
chemists  of  eminence  regard  silica  as  being  an  acid    rather  than 
an  earth.      This  opinion  is  founded  upon   the   fact   that   it  satu- 
rates the  fixed  alkalies,  and  that  in  its  natural  combinations,  it  sat- 
urates the  other  earths.      It  has  therefore  been  called  the  silicic 
acid,  and  its  compounds,   silicates.     This  however,  appears  to  be 
a  forced   arrangement.     In   every  other  particular,   silica  is   quite 
foreign  from  the  nature  of  acids,  and  as  regards  its  combinations  with 
earthy  and  alkaline  bases,  it  is  not  uncommon  for  one  oxide  to  unite 
with  another ;  the  alkalies  dissolve  many  metallic  oxides,  and  potassa 
and  soda  readily  dissolve  alumina,  and  should  therefore,  upon  this  prin- 
ciple be  called  acids.     The  student  will,  however,  do  well  to  remem- 
ber that  the  silicates  mentioned  in  modern  books,  and  frequently  in 
the  analyses  of  minerals,  are  compounds  of  silica  with  bases.     Wheth- 
er we  regard  silica  as  an  earth  or  an  acid,  there  appears  no  reason 
why  these  combinations  should  not  take  place  in  definite  proportions, 
such  as  are  actually  found  to  exist. 

5.  COMBINING  WEIGHT. — According  to  Dr.  Thomson,  it  is  16, 
of  which  one  proportion  is  oxygen,  8,  and  one  silicium,  8.     Accord- 
ing to  Berzelius,  it  is  1  proportion  of  silieinm,  and  3  of  oxygen. 


*  First  Principles,  Vol.  I,  p.  191. 

t  Not  first  by  Dr.  Clarke,  as  stated  by  Dr,  Henry.  Vol.  I,  p.  643.  10th  London  cd. 


EARTHS,  277 


SILICIUM,    OR    SILICON.* 

Remark. — The  student  may  omit  this  head  until  he  has  studied 
the  fluoric  acid,  and  its  compounds. 

1.  PROCESS. 

(a.)  Iron  seven  parts,  silica  five,  and  from  {  to  f  of  soot,  fused  in 
a  blast  furnace,  gave  an  alloy  of  silicium  and  iron. 

(b.)  Purified  potassium,  when  heated  in  silicated  fluoric  acid  gas? 
burns,  condenses  the  gas,  and  gives  a  brown  substance. 

(c.)  This  boiled  in  water,  and  dried,  burns  in  oxygen  gas,  and 
produces  only  silicated  fluoric  acid,  and  silica. 

(d.)  "  The  residue,  treated  with  fluoric  acid,  gave  silicated  fluoric 
acid,  and  its  color  was  rendered  much  darker." 

(e.)  "  Thrown  on  a  filter,  washed  and  dried,  it  was  pure  silicium, 
which  may  be  obtained  also  by  heating  potassium  in  a  glass  tube, 
with  dry  silicated  fluate  of  potash." 

(/.)  "  The  product  by  being  well  washed  with  water,  yields  a 
compound  of  silicium  and  hydrogen,  from  which  the  latter  may  be 
detached  by  heating  in  a  crucible. "f 

2.  PROPERTIES. 

(a.)  Color,  deep  nut  brown,  without  lustre,  and  acquires  no  bril- 
liancy from  a  burnisher  ;  no  resemblance  to  a  metal ;  resists  friction 
like  an  earthy  substance. 

Incombustible,  in  common  air,  or  even  in  oxygen  gas.J 


*  Sir  H.  Davy,  (as  already  mentioned  with  respect  to  lime,)  by  driving  the  potassi- 
um through  the  earths  heated  intensely,  succeeded  so  far  in  decomposing  several  of 
them,  that  the  mass  exhibited  metallic  points,  and  the  potassium  became  potash. 
No  considerable  masses  of  metals  were  obtained  in  this  way,  but  in  general  there 
was  sufficient  evidence  that  they  were  decomposed,  and  in  this  manner  he  was  the 
first  to  ascertain  that  silica  is  a  compound  of  oxygen  and  a  base. 

t  Ann.  de  Ch.  etde  Phys.  Vol.  XX  VII,  337.— Am.  Jour.  Vol.  IX,  p.  377.— Hen- 
ry, Vol.  I,  p.  641,  10th  Ed. 

The  best  method  of  decomposing  silica,  is  by  taking  it  in  the  form  of  double  fluale 
of  silica  and  potash  or  soda;  the  latter  is  preferred,  because  it  contains  the  greatest 
quantity  of  silica.  To  prepare  it,  the;  aqueous  solution  of  silicated  fluoric  acid  is 
mixed  with  the  carbonate  of  soda,  when  the  double  salt,  which  is  nearly  insoluble, 
precipitates,  and  is  washed  and  dried  at  a  heat  above  212°.  This  is  stratified  with 
thin  slices  of  potassium,  in  a  glass  tube,  hermetically  sealed  at  one  end,  and  the 
mass  must  be  uniformly  heated,  and  at  once,  by  a  spirit  lamp.  Even  before  ignition 
the  silica  is  reduced  with  a  hissing  noise,  and  some  appearance  of  heat,  but  if  the 
matter  is  dry  no  heat  is  evolved. 

The  resulting  brown  mass,  after  being  thoroughly  freed  from  acid  and  saline  mat- 
ter, by  water  repeatedly  applied,  at  first  cold,  and  in  abundance,  and  at  last  boiling- 
hot,  is  then  ignited,  to  expel  hydrogen.  It  is  then  washed  in  diluted  hydro-fluoric 
acid,  to  remove  any  siliceous  particles,  and  is  again  washed  and  dried.  For  the  de- 
tails see  Ure's  Diet  2d  Ed.  p.  718,  and  Ann.  of  Phil.  Vol.  XXVI,  p.  116. 

t  When  first  obtained,  and  before  it  is  freed  from  hydrogen,  it  burns  when  heated, 
even  in  the  open  air,  but  if  carefully  ignited  first,  in  seclusion  from  the  air,  to  expel 
the  hydrogen,  it  becomes  uninflammable. 


278  EARTHS. 

(b.)  Not  attacked  by  water,  or  sulphuric,  nitric,  or  nitro-muriatic 
acid.  Infusible,  and  unalterable  by  the  blow  pipe,  and  apparently 
one  of  the  most  infusible  of  bodies. 

(c.)  Fluoric  acid,  with  a  little  nitric,  attacks  it  vigorously. 

(d.)  After  ignition,  chlorate  of  potash  does  not  affect  it  at  any 
temperature.  Nitre  acts  upon  it  violently  at  a  white  heat.  If  a  frag- 
ment of  carbonate  of  soda  be  introduced  into  the  mixture,  it  detonates. 

(e.)  Vapor  of  sulphur  unites  with  the  ignited  silicium,  and  becomes 
incandescent. 

(/.)  The  resulting  sulphuret  decomposes  water  rapidly,  and  evolves 
sulphuretted  hydrogen ;  silica  is  generated,  and  the  water  dissolves 
it,  and  becomes  gelatinous,  but  after  it  is  dry,  it  remains  a  cracked 
mass,  and  is  entirely  insoluble  in  acids.  It  is  observed  that  this  solu- 
bility of  silica  just  formed,  may  explain  the  existence  of  siliceous 
crystals  in  closed  cavities,  which  could  never  have  contained  water 
enough  for  the  solution  of  the  materials,  unless  they  were  originally 
in  a  much  more  soluble  state. 

(g.)  Silicium  burns  in  chlorine  at  a  red  heat,  and  forms  a  yel- 
low volatile  liquid,  smelling  like  cyanogen,  and  depositing  silica  on 
the  addition  of  water. 

(h.)  Detonates  when  heated  with  carbonate  of  potash,  and  with 
the  hydrates  of  fixed  alkalies,  and  of  baryta,  producing  at  a  tempe- 
rature below  redness,  vivid  incandescence ;  it  acts  upon  the  alkali 
of  nitre,  after  the  acid  is  destroyed  by  heat. 


(i.)  JL  non-conductor  of  electricity. 


j.)  Alloys  of  silicium  are  obtained  by  heating  silica  along  with 
other  metals,  but  silicium  once  extricated  from  oxygen,  does  not  form 
alloys. 

(k.)  It  stains,  and  sticks  strongly,  even  when  dry,  to  the  glass 
vessels  in  which  it  is  kept. 

(1.)  When  silicium  is  heated  in  vapor  of  potassium  it  takes  Jire, 
producing  a  compound  of  silicium  and  potassium. 

Remarks. — It  is  not  easy  to  class  silicium.  It  can  scarcely  be 
called  a  metal,  as  it  is  infusible,  is  a  non-conductor  of  electricity, 
and  has  none  of  the  physical  properties  of  a  metal.  It  may  be  re- 
garded as  a  combustible,  since  it  burns  in  chlorine,  and  those  who 
choose  to  consider  its  combination  with  sulphur  and  potassium,  with 
emission  of  heat  and  light,  as  a  combustion,  will  of  course  add  those 
instances  as  proofs  of  its  combustibility.  On  the  whole,  it  is  perhaps 
more  allied  to  boron  and  carbon,  than  to  the  metals ;  but  carbon  has 
two  metallic  properties ;  it  is  a  conductor  of  electricity,  and  in  the 
form  of- plumbago,  and  of  fused  charcoal,  it  has  the  metallic  lustre. 
Some  of  the  metals,  as  uranium,  titanium,  and  columbium,  are  rather 


*  See  Aim.  de  Chem.  et  de  Phys.  Vol.  XXVII,  p.  337,  and  Ure's  Diet.  p.  719, 


EARTHS.  279 

remote  in  their  properties  from  those  usually  assigned  to  metals.—- 
Berzelius. 

GLASS.* 

1.  HISTORY. — Known  to  the  ancients. — Glass  beads  were  found 
among  the  ornaments  of  mummies  in  the  catacombs,  near  Memphis, 
supposed  to  be  1600  years  older  than  the  Christian  era  ;  glass  was 
known  to  the  Romans,  and  glass  vessels  were  discovered  in  the  hous- 
es of  Herculaneum,  and  a  coarse  glass  in  the  windows  of  the  houses 
in  Pompeii,  which  were  destroyed  by  an  eruption  of  Vesuvius,  A.  D. 
79  ;    glass   lachrymatories  are  found  in   the  tombs  of  the  ancient 
Greeks. f     Glass  was  however,  with  the  ancients,  merely  an  article 
of  luxury  and  curiosity,  and   it  is  only  in  modern  times  that  it  has 
come  into  general  use. 

In  Europe,  it  was  first  made  at  Venice,  and  its  use,  in  windows 
of  private  houses,  was  introduced  into  England  in  the  tenth  century, 
nor  was  it  common  until  the  13th  or  14th  century. 

2.  COMPOSITION. — Essentially  a  compound  of  silica,  and  fixed 
alkali,  with  however,  various  adventitious  ingredients;  sometimes 
glass  is  made  of  lime,  or  of  the  coarsest  refuse  ashes,  and  sand. 

3.  Principal  kinds.' — Flint  glass  ;  crown,  or  window  glass ;  broadr 
or  coarse  window  glass  ;  'plate  glass  ;•  green  bottle  glass. 

(a.)  Flint  Glass.^ — 120  parts  clean  white  sand,  40  purified  pearl 
ashes,  35  litharge,  or  minium,  13  nitre,  and  a  little  oxide  of  manga- 
nese ;  or  100  white  sand,  80  to  85  red  oxide  of  lead,.  35  to  40  of  pearl 
ashes,  2  or  3  of  nitre ;  or,  (in  England,)  purified  Lynn  sand  tOO*  parts? 
litharge,  or  red  lead,  60,  purified  pearl  ashes  30.  To  remove  the- 
color,  derived  from  combustible  matter,  or  oxide  of  iron,  a  little  nitre,., 
or  black  oxide  of  manganese,  or  arsenic  is  added  ;  the  oxigen  con~ 
tained  in  these  substances,  either  burns  the  combustible  matter,  or 
brings  the  metallic  oxides  that  may  be  present,  to  such  a  state  that 
they  do  not  color  the  glass.  The  fusion  takes  about  thirty  hoursv 
The  lead  gives  to  this  species  of  glass  greater  toughness  and  softness,* 
so  that  it  can  be  cut,  ground,  and  highly  polished,  and  greater  densi- 


*  Glass  is  an  example  of  what  is  called  a  vitrification.  Many  earthy  and  saline 
substances,  and  metallic  oxides,  either  alone,  or  mixed,  become  by  fusion,  dense,  hard, 
brittle,  shining  bodies,  usually  breaking  with  aconchoidal  fracture,  and  having  more 
or  less  of  transparency.  The  slag  and  scoriae  of  furnaces  are  imperfect  vitrifications. 

t  Specimens  were  brought  out  by  Mr.  Jones,  author  of  "  Naval  Sketches,"  anrf 
are  now  in  the  Cabinet  of  Yale  College;  they  are  supposed  to  be  2200  years  oldV 
Some  of  them  are  beautifully  irised  ;  the  glass  is  perfect,  and  is  a  little  greerrin  its 
shade  of  color. 

|  Called  flint  glass,  because  it  was  formerly  made  from  flints ;  and  it  has  beei* 
called  crystal  glass,  being  sometimes  made  from  rock  crystals ;  both  are  ignited  and 
thrown  into  water  to  crack  them,  and  they  are  then  pulverized. 


280  EARTHS. 

ty,  and  higher  refractive  power.     It  is  the  glass  of  our  tables,  of  op- 
tical instruments,  and  lustres. 

(b.)  Crown  Glass. — 200  parts  of  good  soda,  (or  pearl  ashes,) 
300  pure  sand,  33  lime,  250  to  300  ground  fragments  of  glass  ;  this 
last  addition  is  not  essential ;  or,  by  measure,  fine  sand  purified  5, 
best  kelp,  ground,  1 1  ;  by  weight,  sand  200,  kelp  330.  Professor 
Sweigger  discovered  that  sulphate  of  soda  might  be  used  in  the  man- 
ufacture of  glass,  and  his  proportions  are,  sand  100,  dry  sulphate  of 
soda  50,  dry  quick  lime,  in  powder,  17  to  20,  charcoal  4.  There- 
suit  is  a  good  glass ;  the  sulphate  of  soda,  aided  especially  by  the 
•charcoal,  is  decomposed,  and  its  soda  combines  with  the  silica  and 
the  lime  aids  in  producing  the  vitrification.  The  materials  of  glass 
are  combined,  in  part,  by  a  preliminary  operation,  called  fritting, 
performed  in  a  furnace,  by  which  sulphur  and  other  volatile  mat- 
ters are  expelled,  previous  to  the  full  fusion,  and  the  alkali  is  brought 
into  combination  with  the  silica,  so  that  it  is  not  volatilized  by  a 
higher  heat. 

(c.)  Broad  glass. — Soap  maker's  waste  2,*  sand  1,  kelp  1,  mix- 
ed, dried  and  fritted ;  or,  soap  boiler's  waste,  6  bushels,  3  of  kelp, 
and  4  of  sand  ;  these  form  a  pretty  good  broad  glass.  The  materi- 
als are  calcined  for  20  or  30  hours  before  fusion,  and  then  it  requires 
12  or  15  hours  to  melt  them  into  perfect  glass. 

(d.)  Plate  glass — 300  Ibs.  sand,  200  soda,  30  lime,  32  oz.  man- 
ganese, 3  oz.  azure,  and  300  Ibs.  fragments  of  glass ;  or  pure  sand 
43,  dry  soda  26.5,  pure  quick  lime  4,  nitre  1.5,  broken  plate  glass 
25  =  100,  from  which  90  parts  of  good  plate  glass  may  be  obtained. 

(e.)  Bottle  glass. — Common  sand,f  100  parts,  30  of  varec  or 
coarse  kelp,  160  leached  ashes,  30  pure  ashes,  80  of  brick  clay, 
about  100  broken  glass ;  or,  soap  maker's  waste  and  river  sand,  in 
proportions  determined  by  practice.  Common  sand  and  lime,  with 
some  common  clay,  and  sea  salt,  form  a  good  mixture  for  bottle  glass. 

3.  Pastes  are  artificial  imitations  of  the  gems. — They  are  very 
fine  glass,  rendered  fusible  by  borax  and  other  fluxes,  and  stained  by 
oxides  of  metals.  Rock  crystal,  or  other  very  pure  siliceous  mat- 
ter, is  selected,  pulverized  very  fine,  and  mixed  with  the  other  sub- 
stances ;  the  following  examples  will  shew  the  composition. 

Pulverized  rock  crystal,  or  flint,  8  oz.  purified  pearl  ashes,  24  oz. 
these  are  fritted  together,  and  then  mixed  with  12  oz.  of  white  lead, 


*  Consisting  of  refuse  lime,  that  had  been  used  to  give  causticity  to  the  alkali, 
the  insoluble  part  of  the  kelp  or  barilla,  and  some  salt  and  water,  all  in  a  pasty  state. 
—  Ure.  N 

t  lu  England,  the  government  will  not  permit  any  but  coarse  sand  to  be  used  in 
this  manufacture,  lest  (lie  common  glass  should  be  so  good  that  the  sale  of  the  flint 
and  other  superior  kinds  of  glass,  which  pay  a  higher  duty,  should  be  diminished. — 
Parkes. 


EARTHS.  281 

and  1  oz.  of  borax — after  fusion,  5  drachms  of  nitre  are  added  ;  or, 
rock  crystal  pulverized,  3  oz.,  white  lead,  8  oz.,  and  borax,  2  oz., 
and  half  a  grain  of  manganese.  This  is  a  paste  in  which  the  lead 
and  borax  answer  the  purpose  of  a  flux. 

Some  principal  colors  are  given  by  the  following  oxides  of  metals. 
Antimony  gives  yellow,  and  the  same  is  produced  by  muriate  of  sil- 
ver, and  by  oxide  of  zinc,  white  clay,  and  yellow  oxide  of  iron ; 
manganese  produces  violet ;  gold,  many  shades  of  violet,  red  and 
purple  ;  cobalt,  blue  ;  chrome,  green,  or  red  ;  iron,  red,  and  a  great 
many  other  colors  and  shades  ;  and  many  varieties  are  imparted  by 
mixtures  of  different  oxides.  Fluxes  for  the  colors  are  made  of 
borax,  pearl  ashes,  lead,  &c.  These  imitations  of  the  gems,  except 
in  lustre,  are  often  equal  in  beauty  to  the  originals,  but  they  are  soft, 
and  easily  defaced. 

(g.)  Stained  glass. — The  art  of  staining  glass  was  introduced  into 
England,  in  the  13th  century,  in  the  reign  of  king  John.  Many  of 
the  ancient  Gothic  churches  in  Europe,  are  ornamented  by  stained 
glass,  the  panes  of  the  windows  having  pictures  painted  upon  them. 
The  glass  used  for  this  purpose,  is  made  without  oxide  of  lead,  be- 
cause that  addition  would  make  it  too  fusible,  so  that  it  would  lose 
its  shape  during  the  second  heating.  The  colors,  ground  in  water, 
are  laid  on  the  glass,  which  is  heated  under  a  muffle,  until  the  colors 
are  melted,  and  united  to  the  glass ;  and  the  pieces,  to  prevent  their 
bending,  are  supported  upon  the  biscuit  of  unglazed  porcelain,  or 
some  other  suitable  substance.* 

(h.)  Medallions  encased  in  glass.— They  appear  to  be  something 
like  the  biscuit  of  porcelain  introduced  into  the  glass,  while  in  fusion  ; 
they  are  called  crystallo  ceramie,  and  are  very  beautiful. f 

(i.)  Enamels  are  glasses,  more  or  less  opake,  stained  with  various 
colors  ;  one  of  the  most  common  is  stained  by  oxide  of  tin  or  oxides 
of  tin,  arsenic  and  lead  more  or  less  mixed,  as  in  watch  faces. 

Dr.  Bigelow  informs  us,J  that  the  beautiful  imitation  of  porcelain, 
made  in  Boston,  and  now  seen  in  the  shops,  is  flint  glass,  containing 
a  portion  of  white  arsenic,  upon  which  its  opacity  depends. 

Remarks. — Green  glass  is  much  harder  and  less  fusible  than  white 
flint,  and  as  it  contains  no  lead,  it  is  also  much  fitter  to  contain  cor- 
rosive chemical  agents.  Glass  is  very  ductile,  as  is  proved  by  its 
being  spun  into  the  most  delicate  threads  ;  it  is  highly  elastic,  form- 
ing the  finest  toned  bells  and  musical  instruments ;  it  expands  and 
contracts  less  than  any  other  substance  by  variation  of  temperature, 

*  I  have  seen  modern  stained  glass  in  the  windows  in  the  University,  Cambridge 
Eng.  and  in  Hartford,  Conn,  (the  latter  of  Boston  manufacture,)  less  beautiful, 
however,  than  the  ancient. 

t  Heads  of  Washington,  Franklin,  Napoleon,  and  other  distinguished  persons, 
have  been  executed  in  this  way.  t  Technology,  460. 

36 


282  EARTHS. 

and  might  therefore  be  used  for  clock  pendulums  ;  it  is  a  bad  con- 
ductor of  heat,  and  a  large  mass  of  it  poured  in  fusion  into  water,  will 
remain  red  hot  in  the  inside,  for  several  hours  after  the  outside  is  solid. 

3.  MECHANICAL  OPERATIONS. — It  would  exceed  the  limits  of  a 
work  like  this,  to  describe  even  the  outlines,  of  the  ingenious  opera- 
tions by  which  glass  is  fabricated  into  the  various  forms  in  which  we 
see  it.  In  general,  it  is  blown  by  the  breath  of  the  artist,  injected 
through  an  iron  tube,  to  which  the  melted  glass  is  made  to  adhere, 
by  dipping  and  rolling  one  of  its  ends,  repeatedly  in  the  crucible ; 
and  in  the  early  part  of  the  operation,  while  it  is  inflated,  it  is  rolled 
on  a  smooth  iron  plate.  I  will  briefly  describe  a  few  cases,  most  of 
which  I  have  seen,  and  they  will  serve  as  examples  for  the  rest.  A 
porter  bottle  is  partly  blown,  and  then  allowed  to  drop  into  a  mould 
of  copper,  brass,  or  iron,  in  which,  by  a  vigorous  inflation,  it  receives 
its  form ;  the  bottom  is  indented  to  make  it  stand  ;  the  mould  opens 
with  a  hinge,  and  another  workman  attaches  a  rod,  having  a  little 
melted  glass  upon  it  to  the  bottom  of  the  bottle  ;  the  neck  is  cracked 
off  by  touching  it  with  an  instrument  wet  with  cold  water,  and  the 
broken  mouth,  being  again  heated,  is  shaped  by  introducing  a  revolv- 
ing iron  into  it,  and  a  coil  of  melted  glass  is  wound  around  to  give 
it  strengh ;  it  is  then  carried  away  to  the  annealing  furnace,  to  be 
gradually  cooled.  Glasses  consisting  of  several  parts,  are  blown  sep- 
arately, opened,  moulded,  shaped  and  stuck  together  while  hot  ;  the 
foot  of  a  wine  glass  is  blown,  as  well  as  the  conical  part. 

A  glass  tube  is  drawn,  by  blowing  a  little  into  a  mass  of  melted 
glass  on  the  end  of  the  iron  tube,  and  then  an  assistant  pulls  the  mass 
with  iron  pincers,  and  moves  off  rapidly  or  slowly,  as  the  tube  is  to 
be  coarser  or  finer. 

Plate  glass  is  cast  on  an  iron  table  ;*  an  iron  cylinder  of  five 
hundred  pounds  weight  or  more,  is  passed  over  it  to  spread  it 
smoothly,  and  it  is  finished  by  being  ground  and  polished.  Plates 
have  been  made  of  twelve  feet  by  six.  The  smaller  glass  plates  are 
blown,  opened  by  a  chisel  and  mallet,  and  cut,  while  hot,  by  shears, 
spread  open  upon  a  table,  and  afterwards  annealed  and  cut  by  the 
diamond.  Plates  can  be  made  in  this  way,  of  four  or  five  feet,  by 
two  or  three.  Window  glass  is  blown,  and  either  cut  open  and 
spread ;  or  in  the  best  kinds,  after  being  blown  into  a  huge  globe, 
this  is  fixed  at  the  bottom,  to  another  iron  tube,  or  rather  an  iron 
rod  ;  the  neck  is  cracked  off,  and  the  mouth  is  heated  at  a  flaming 
furnace,  while  the  bottle  is  made  to  revolve  rapidly,  and  by  the  cen- 
trifugal force,  the  mouth  opens  and  widens,  and  the  globe  suddenly 
expands  into  a  wheel,  forty  eight  or  fifty  inches  in  diameter,  called 
by  the  workmen,  a  table  ;  this  operation  is  called  flashing,  and  is 

*  Copper  tables  and  rollers  were  formerly  employed,  but  the  copper  is  apt  to 
crack. 


EARTHS.  283 

very  beautiful.  The  glass,  after  being  annealed,  is  cut  up  into  squares 
by  a  diamond  ;  the  centre  piece  by  which  the  wheel  was  supported, 
is  called  the  bull's  eye,  and  is  often  seen  in  entry  windows.  Broad 
glass  is  blown  into  a  conical  form  ;  cracked  longitudinally  while  hot, 
by  touching  it  with  a  cold  wet  iron,  and  it  is  then  spread  out  on  a  ta- 
ble, whence  its  name  ;  it  is  afterwards  annealed  and  cut. 

The  annealing  of  glass,  which  means  the  cooling  of  it,  very  slow- 
ly, in  a  peculiar  kind  of  furnace,  is  important  to  prevent  its  crack- 
ing by  slight  movements,  or  jars,  or  variations  of  temperature. 

Prince  Rupert's  drops  are  made  by  pouring  melted  green  glass 
into  water,  when  the  portions  assume  a  tadpole  shape  ;  they  will  bear 
the  moderate  blow  of  a  hammer,  if  lying  on  a  smooth  table,  but  if 
the  point  is  broken  off,  they  explode  into  a  thousand  pieces.  That 
this  peculiarity  depends  on  an  unequal  contraction  produced  by  sud- 
den cooling,  is  evident,  because  if  the  drops  are  gradually  heated  red 
hot,  and  gradually  cooled,  they  will  no  longer  fly  on  having  the 
point  broken. 

The  Bologna  vial  is  blown  with  a  thick  bottom,  but  is  cooled  in 
the  air,  without  being  annealed  ;  it  will  bear  to  be  struck  upon  a  table 
with  some  force,  but  if  a  fragment  of  glass  or  sand  be  dropped  into  it, 
it  flies  to  pieces,  and  frequently  it  does  so  by  slight  changes  of  tem- 
perature ;  even,  as  I  have  observed,  by  the  warmth  of  the  hands. 
Cups  of  green  glass,  unannealed,  have  been  made  three  inches  thick 
at  bottom,  which  were  not  broken  by  a  musket  ball  falling  from  a 
considerable  height,  but  were  shivered,  by  a  piece  of  flint  of  two 
grains  weight  falling  into  them. 

SEC.  VI. — ALUMINA. 

1.  NAME. — From  alumen,  the  latin  of  alum,  which  has  this  earth 
for  its  basis  ;  called  also  the  argillaceous  earth.     Indicated  by  Geof- 
froy,  in  1727,  established  by  MargrafF,  of  Berlin,  1756.     Formerly 
called  argil,  because  it  was  the  basis  of  clays. 

2.  PREPARATION. 

(a.)  To  a  solution  of  alum,*  in  20  parts  of  water,  add  liquid  ammo- 
nia till  precipitation  ceases  :  or,  precipitate  by  bicarbonate  of  potash ; 
as  a  little  sulphuric  acid  is  apt  to  adhere,  it  may  be  re-dissolved  in 
nitric  acid,  and  the  solution  tried  for  sulphuric  acid,  by  nitrate  of  ba- 
rytes ;  when  there  is  no  farther  milkiness,  it  may  again  be  precipi- 
tated by  the  above  reagents,  or  the  nitrate  may  be  decomposed  by 

heat.f 

(0.)  Or,  alum  purified  from  iron,  by  repeated  crystallizations,  is 
dissolved  in  4  or  5  parts  of  water,  at  212°  ;  add  carbonate  of  potash 

*  Alum  is  apt  to  contain  iron,  which  will  remain  when  the  salt  is  decomposed,  and 
the  earth  dissolved  by  potassa ;  or,  if  dissolved,  it  will,  after  a  few  hours,  precipitate 
in  brown  flocks. 

t  Ann.  de  Chim.  XXXII,  p.  64. 


284  EARTHS. 

in  slight  excess,  to  prevent  the  formation  of  sub-sulphate  ;  digest  a 
little  while,  filter  and  wash  the  precipitate  with  boiling  water,  to  re- 
move the  acid  entirely ;  but  as  some  alkali  may  adhere  to  the  earth, 
re-dissolve  it  in  dilute  muriatic  acid,  and  decompose  by  ammonia,  or 
its  carbonate ;  wash  the  precipitate  thoroughly,  and  give  it  a  white 
heat,  when  it  will  be  pure. 

(c.)  When  alum  is  composed  of  'sulphuric  acid  and  alumina,  with 
ammonia,  and  without  any  other  alkali,  the  earth  may  be  obtained  by 
heat  alone,  which  expels  the  ammonia,  and  decomposes  the  acid. 

(d.)  Galvanism  discovers  minute  portions  of  the  fixed  alkalies  and 
acids  in  the  alumina  prepared  as  above,  but  not  when  it  is  dissolved 
in  muriatic  acid,  and  precipitated  by  ammonia.* 

3.  PROPERTIES. 

(a.)  Tasteless,  inodorous,  insoluble  in  water  ;  no  effect  on  test  flu- 
ids ;  infusible  in  furnaces.  Sp.  gr.  2.  No  alkaline  property,  ex- 
cept that  of  uniting  with  acids. 

(b.)  Although  insoluble  in  water,  it  attracts  it  powerfully  ;  when 
dry,  it  adheres  to  the  tongue  ;  when  precipitated,  and  moderately 
dried,  it  is  a  hydrate,  half  of  whose  weight  is  water,  which  cannot  be 
expelled  except  by  a  white  heat. 

After  ignition,  it  attracts  water  so  fast  from  the  air,  that  balances 
show  the  increase  of  weight,  f — Henry.  Dr.  Thomson  states  that 
there  are  two  hydrates;  the  one  composed  of  1  equivalent  of  alu- 
mina, and  2  of  water,  forming  a  bi-hydrate ;  the  other  containing 
one  equivalent  of  each. 

(c.)  Easily  diffusible  in  water,  and  forms  with  it  a  plastic  mass  ; 
and  whether  dry  or  moist,  is  impalpable  between  the  fingers,  or  teeth, 
not  being  harsh  and  gritty,  like  silica  ;  nor  alkaline  like  lime,  baryta, 
and  strontia  ;  nor  rough,  like  magnesia. 

(d.)  If  precipitated  from  a  concentrated  solution  of  an  alkali,  it  is 
a  light  friable  powder,  and  adhesive  to  the  tongue. 

(e.)  If  from  a  dilute  solution,  the  dried  precipitate  is  transparent, 
yellow,  and  brittle,  compact,  not  earthy,  and  does  not  adhere  to  the 
tongue;  this  retains  water  forcibly,  and  has  .15  of  it,  even  after  in- 
candescence. 

(/.)  Infusible  in  furnaces,  but  fused  by  pure  oxygen  gas,  on  char- 
coal, and  by  the  flame  of  the  compound  blowpipe,  into  an  enamel,  or 
a  glass. 

(g.)  Dissolved  in  the  humid  way  by  the  fixed  alkalies,  but  very 
imperfectly  by  ammonia ;  the  earth  precipitated  from  alum,  potash 
or  soda,  is  re-dissolved  by  adding  those  alkalies  in  excess,  and  pre- 
cipitated again  by  an  acid. 

*  Phil.  Trans.  1800,  Davy. 

t  In  Berzelius'  hands,  15  1-2  per  cent,  were  gained  in  a  dry,  and  33  in  a  humid  air. 


EARTHS.  285 

(h.)  Alumina  and  baryta,  in  equal  parts,  boiled  together  in  water, 
'are  dissolved. 

(i.)  Five  parts  of  strontia  being  boiled  on  1  of  alumina,  a  portion  is 
dissolved,  and  a  compound  of  strontia  and  alumina  is  left  undissolved  ; 
they  unite  also  by  fusion. 

(j.)  Alkaline  solution  of  alumina,  added  to  lim_e  water,  produces 
an  insoluble  precipitate  of  lime  and  alumina. 

(k.)  The  same  alkaline  liquor  boiled  on  lime  dissolves  no  more 
than  the  water  alone  will  dissolve  ;  if  alumina  be  mixed  with  the  lime, 
much  more  lime  is  taken  up  than  before. 

(I.)  Mixture  of  alumina  and  lime,  the  latter  being  in  excess,  melts 
under  oxygen  gas,  directed  upon  burning  charcoal,  but  in  no  propor- 
tions in  a  common  furnace. 

(m.)  Alkaline  solution  of  silica,  with  alkaline  solution  of  alumina, 
on  being  mixed,  gives  a  precipitate  of  silica  and  alumina,  which  fuses 
with  an  intense  heat,  into  a  milky  glass  or  enamel. 

(n.)  Not  soluble  in  alkaline  carbonates. 

(o.)  Alumina  unites  by  fusion  with  the  fixed  alkalies,  and  with 
most  of  the  earths. — Henry. 

(p.)  This  earth  attracts  coloring  matter  powerfully — see  dyeing, 
under  vegetables. 

(q.)  CONTRACTS  PERMANENTLY  IN  THE  FIRE  ;  and  becomes  so 
hard  as  to  give  fire  with  steel.  This  is  from  an  intimate  union  of  the 
molecules,  and  especially  when  silica  is  present,  as  in  the  natural 
clays. 

Wedgewood's  pyrometer  depends  on  this  fact. — See  heat,  and 
the  means  of  measuring  heat. 

4.  POLARITY. — Electro  positive ;  it  is  separated  at  the  negative 
pole  in  the  galvanic  circuit. 

5.  COMBINING  WEIGHT. — 18   according   to  Dr.  Thomson  and 
Gay-Lussac,  but  chemists  are  not  perfectly  agreed  as  to  this  number. 

6.  DISTINCTIVE  CHARACTERS. 

(a.)  Plastic  with  water,  and  imparts  this  property  to  large  mix- 
tures of  other  earths. 

(b.)  Precipitated  as  a  hydrate,  by  alkaline  carbonates,  and  by 
pure  ammonia. 

(c.)  Precipitated  by  pure  potassa  and  soda,  and  immediately  re- 
dissolved  by  an  excess  of  those  alkalies ;  some  choose  to  call  this  an 
acid  property,  but  the  alkali  is  not  fully  neutralized. 

6.  NATURAL  HISTORY  AND  USES. 

In  various  forms  and  combinations,  it  is  one  of  the  most  abundant 
substances  in  nature.  Clays  are  composed  of  alumina,  for  their 
characteristic  ingredient,  mixed  with  silica,  oxide  of  iron  and  other 
substances.  Those  clays  which,  when  burned,  become  red,  contain 
oxide  of  iron,  as  is  seen  in  our  red  bricks. 


286  EARTHS. 

Alumina  enters  more  or  less  into  the  composition  of  most  soils, 
and  it  generally  forms  strata  in  valleys  and  low  grounds  and  plains, 
where  it  arrests  the  water  which  has  filtered  down  from  the  hills,  and 
causes  it  to  issue  from  the  ground,  in  springs  and  rivulets.  On  ac- 
count of  its  impermeability  to  water,  clay  is  employed  in  the  con- 
struction of  tanner's  vats,  of  artificial  mill  ponds,  &c.  where  it  is  wish- 
ed to  retain  the  water. 

In  soils,  this  earth  is  of  the  first  importance  ;  perhaps  it  is  not  too 
much  to  say,  that  there  cannot  be  a  good  soil  without  it.  Its  pe- 
culiar office  appears  to  be,  to  retain  moisture,  and  to  prevent  the 
waste  of  the  soluble  parts  of  animal  and  vegetable  manures,  which 
so  rapidly  filter  through  siliceous  sand  and  gravel.  Still,  a  soil  may 
contain  too  much  alumina ;  it  will  then  be  stiff,  cold,  and  difficultly 
penetrated  by  the  roots  of  plants  ;  but  if  it  is  mixed  with  a  good  pro- 
portion of  siliceous  sand  and  gravel,  it  will  be  warm,  still  retentive  of 
moisture,  and  sufficiently  mellow. 

Lime  is  an  excellent  ingredient  in  soils,  as  will  be  mentioned  more 
particularly  under  the  carbonate  of  that  earth. 

Alumina  exists  abundantly  in  rocks,  especially  in  felspar,  which  is 
a  constituent  of  granite  and  gneiss ;  in  clayslate,  steatite,  asbestus, 
and  serpentines,  and  in  a  great  variety  of  minerals.  It  is  nearly  pure 
in  the  sapphire,  and  all  the  most  precious  oriental  gems ;  it  forms 
nearly  the  whole  of  corundum  ;  it  exists  in  a  vast  proportion  of  min- 
erals, and  forms  a  large  part  of  the  crust  of  the  globe. 

PORCELAIN  AND  POTTERY. 

In  all  the  manufactures  which  go  under  the  general  name  of  pot- 
tery, from  the  coarsest  tile  or  water  pot,  to  the  most  beautiful  porce- 
lain— in  chemical  lutes,  in  fuller's  earth,  and  bricks,  silica  and  alu- 
mina, in  certain  proportions,  are  the  essential  ingredients. 

History. — Known  from  the  remotest  antiquity  ;  the  most  barbarous 
nations  fabricate  rude  vessels  of  baked  earth,  as  well  as  by  hollowing 
out  soft  stones ;  bricks  were  employed  in  the  tower  of  Babel,*  two 
thousand  years  before  the  Christian  era,  and  they  are  found  in  the  an- 
cient Roman  structures  in  Britainf  and  elsewhere.  Earthen  lach- 
rymatories are  discovered  in  the  tombs  of  the  ancient  Greeks  and 


*  In  Yale  College,  are  some  Babylonish  bricks  brought  out  by  the  late  Mr.  E. 
Lewis,  of  N.  Haven  ;  they  were  never  baked  ;  they  contain  straw  and  bitumen,  and 
some  of  them  have  "  inscriptions  in  the  arrow  headed  character  ;"  the  dimensions 
of  the  largest  are  twelve  and  three  fourths  inches  square  by  three  and  a  half  thick. 

t  In  the  Roman  wall  at  York,  the  bricks  are  seventeen  inches  long,  eleven  broad, 
and  two  and  a  half  thick  ;  and  there  is  in  Yale  College,  a  piece  of  brick  and  mortar, 
trom  Roman  baths  at  Paris,  presented  by  Mr.  Joel  Root,  who  obtained  it  from  the 
ruins. 


EARTHS.  287 

Romans  ;*  the  celebrated  Etruscan  vases  were  found  in  the  tombs 
of  lower  Italy,  f 

Water  pipes  were  made  by  the  ancients.  I  have  one  from  Smyr- 
na, sent  out  by  the  American  missionaries,  which  indicates  its  anti- 
quity by  numerous  layers  of  carbonate  of  lime,  accumulated  in  the 
tube  to  the  thickness  of  three  or  four  inches,  and  evidently  deposited 
from  the  water  which  ran  through  it. 

The  Egyptians  ornamented  the  mummies  in  their  catacombs,  not 
only  with  glass,  but  with  earthen  figures,  some  of  which  were  cover- 
ed with  a  blue  glazing  made  by  the  oxide  of  cobalt,  the  same  mate- 
rial that  is  now  used  for  this  purpose.  Porcelain  was  made  by  the 
Persian,  and  other  eastern  nations,  before  the  Christian  era,  and  the 
art  is  of  high  antiquity  in  China  and  Japan.  It  was  introduced  into 
Europe,  early  in  the  late  century,  and  fabricated  first  in  Saxony  and 
France  ;  it  was  established  in  England,  about  the  middle  of  the 
late  century,  and  the  manufacture  was  brought  to  great  perfection, 
by  the  late  Mr.  Wedgwood.f  The  manufacture  of  porcelain  has 
been  within  a  few  years,  begun  in  the  United  States,^  and  beautiful 
porcelain  is  now  made  at  Philadelphia,  by  Hulme  and  Tucker. 

Materials  of  porcelain. — The  Romish  missionary,  father  D'En- 
trecolles,  early  in  the  18th  century,  sent  home  some  of  the  materials 
used  by  the  Chinese,  and  called  by  them  petuntze  and  kaolin,  the 
former  being  undecomposed  felspar,  and  of  course  fusible  ;  the  lat- 
ter decomposed  and  infusible,  in  consequence  of  the  loss  of  the  al- 
kali, which  is  one  of  its  constituent  principles. 

The  felspar  is  composed  of  silica  about  60  or  70,  alumina  from 
15  to  25,  and  from  10  to  12  per  cent,  of  potash  or  soda. 

Porcelain  differs  from  stone  ware  in  having  a  vitreous  fracture  and 
delicate  translucence,  which  arises  from  its  being  composed  of  one 
fusible  ingredient,  while  the  infusible  one  preserves  the  vessels  from 
losing  their  form  in  the  fire. 

Porcelain  clays  abound  in  this  country,  and  the  materials  from 
Chester  County,  near  Philadelphia,  now  used  there,  are  of  the  first 
order  in  point  of  excellence.  Such  clays  should  be  free  from  iron, 
or  the  ware  will  be  colored. 

Materials  of  pottery. — There  is  no  difference  in  principle  between 
the  materials  of  pottery  and  those  of  porcelain,  except  that  the  latter 

*  Specimens  are  in  Yale  College,  brought  out  by  Dr.  Howe  and  Mr.  Jones. 
Some  of  them  are  supposed  to  be  of  the  age  of  Pericles,  particularly  those  from  the 
tombs  near  Athens.  Dr.  Howe  informed  me  that  he  was  present  when  they  were 
taken  from  the  tombs. 

t  I  saw  a  collection  of  these  in  the  British  museum,  sent  out  from  Italy  by  the 
late  Sir  Wm.  Hamilton. 

t  The  common  pottery  had  been  manufactured  in  England,  time  out  of  mind. 

§  I  believe  that  Dr.  Meade,  of  New  York,  was  the  first  person  who  succeeded  in, 
this  country  in  making  true  porcelain. 


288  EARTHS. 

and  contain  one  fusible  ingredient,  and  are  purer.  The  pottery  being 
opake,  needs  not  tbe  felspar,  and  it  has  a  dull  earthy  fracture  instead 
of  a  vitreous  one. 

The  most  common  earthen  ware  is  made  of  pipe  clay,  often  con- 
taining iron,  which  of  course  colors  the  ware  when  it  is  burned.  A 
clay,  much  used  in  this  country,  is  obtained  from  Amboy,  N.  Jersey, 
and  is  gray,  both  before  and  after  it  is  burned. 

The  plastic  property  possessed  by  moist  clay,  and  by  means  of 
which  it  is  moulded,  depends  on  the  alumina ;  but  the  pieces  would 
crack  and  be  destroyed  by  shrinkage,  were  not  the  alumina  correct- 
ed by  the  silica,  which  is  not  prone  to  shrink  in  the  fire.  If  natural 
clays  then  have  the  requisite  proportions  of  the  two  earths,  and  are 
free  from  iron,  they  have  all  the  properties  that  are  essential ;  and  if 
a  color  is  produced  by  burning,  it  does  not  prevent  the  clay  from 
forming  a  useful  ware,  although  it  may  not  be  beautiful.  Magnesia 
frequently  enters  into  the  composition  of  clays,  and  is  a  valuable  in- 
gredient, as  it  is  a  very  infusible  earth,  and  contracts  but  little  in  the 
fire ;  but  if  there  is  much  lime,  it  will  act  as  a  flux,  and  produce  a  dis- 
torted ware. 

As  the  natural  clays  do  not  always  contain  a  sufficient  portion  of 
siliceous  earth,  it  is  usual,  in  such  cases,  to  mix  with  them  siliceous 
sand  or  ground  flints,  the  clay  being  first  blended  with  water  into  a 
paste,  and  it  is  then  uniformly  mixed  with  the  siliceous  ingredient.* 

Fabrication  of  porcelain  and  pottery. — There  are  important  dif- 
ferences between  the  two,  and  there  are  many  varieties  of  operations 
relating  to  both,  but  a  few  general  facts  may  be  stated.  There  is  no 
analogy  between  these  processes  and  those  by  which  glass  is  made  ; 
they  are  in  fact  directly  opposite ;  glass  is  "  softened  by  heat,  and 
wrought  at  a  high  temperature,  whereas  the  clay  is  wrought  while 
cold,  and  afterwards  hardened  by  heat." — Bigelow. 

There  is  much  labor  in  preparing  the  materials,  the  detail  of  which 
would  be  foreign  from  the  object  of  this  work,  in  which  only  a  few 
of  the  most  important  operations  can  be  mentioned. 

Circular  conical  vessels  are  moulded  upon  the  potter's  wheel,  a 
very  ancient  instrument,  mentioned  by  the  earliest  writers,  sacred 
and  profane.  A  mass  of  the  prepared  clay  is  placed  in  the  centre, 
and  it  revolves  by  a  movement  given  by  the  foot,  or  by  some  other 
power  ;  the  potter,  his  hands  being  moistened,  to  prevent  adhesion, 
one  hand  being  on  the  outside,  and  the  other  within,  gives  it  a  circu- 
lar form,  and  he  employs  sometimes  a  rude  instrument,  like  a  knife, 
to  aid  in  finishing  the  piece.  Many  articles,  modeled  in  this  way, 
being  too  thick,  are  afterwards  turned  in  the  lathe,  to  make  them 
thinner. 

*  Pottery  contains  silica,  two  thirds,  alumina,  from  one  fifth  to  one  third,  and 
sometimes  one  five  hundredth  or  one  two  thousandth  of  lime,  and  iron  from  the 
smallest  portion  to  15  or  20  per  cent. —  Vauquelin,  quoted  by  Parkes. 


EARTHS.  289 

Handles,  spouts,  and  other  appendages  are  made  separately,  and 
are  stuck  on  afterwards,  with  a  thin  paste  of  the  clay,  called  slip. 

Vessels  that  are  to  have  a  peculiar  form,  oval,  scalloped,  fluted, 
&c.  are  made  in  moulds,  usually  of  calcined  plaster  of  Paris, 
which,  by  its  absorbing  power,  aids  in  drying  the  articles,  and  the 
moisture  is  expelled  from  the  moulds  by  heat,  so  that  they  are  soon 
rendered  serviceable  again. 

Burning  or  Baking. — The  vessels,  after  they  are  dried,  either 
in  the  air,  or  in  stove  rooms,  are  placed  in  earthen  cases,  called  seg- 
gars,  and  these  are  so  arranged  that  one  covers  another,  in  the  oven 
or  furnace,  where  they  are  gradually  heated  for  about  12  hours,  by 
flues,  communicating  from  without,  and  the  full  heat  is  maintained 
from  24  to  48  hours  ;  more  or  less,  according  to  the  size  of  the  es- 
tablishment, and  the  nature  of  the  ware.*  The  furnace  being  grad- 
ually cooled,  the  pieces  are  withdrawn,  and  are  then  in  the  state 
of  biscuit,  as  it  is  called  :  it  will  be  a  perfect  pottery,  only  it  is  ab- 
sorbent of  fluids,  and  therefore  cannot  be  used,  except  for  promoting 
evaporation,  when  it  is  desired  that  the  fluid  should  pass  through  the 
pores  and  be  exhaled  from  the  outside.  It  adheres  to  the  tongue, 
because  it  absorbs  its  moisture. 

Porcelain  contracts  so  much  in  baking,  that  some  tablets  which  I 
have  from  the  Royal  Manufactory  at  Sevres,f  in  France,  which  were 
marked  off  into  ten  equal  parts,  are  shrunk  one  division,  comparing 
them  with  those  that  have  not  been  baked. 

Magnesia  very  much  diminishes  the  shrinkage  of  the  porcelain,  and, 
in  the  form  of  steatite,  is  now  employed  by  the  English  manufacturers. 
Great  quantities  of  bones  are  consumed  in  the  English  potteries ; 
it  is  done  for  economy,  for  the  quality  of  the  ware  is  injured,  as  to 
firmness  and  weight,  although  it  is  white  and  translucent. 

Ornamenting. — In  the  state  of  biscuit,  the  figures  are  usually  put 
on ;  in  the  finer  kinds,  by  the  pencil,  and  in  the  most  beautiful  por- 
celain, by  the  best  artists,  with  exquisite  taste  and  skill ;  and  often  a 
separate  figure  or  scene  is  painted  upon  every  piece  of  an  extensive 
set :  the  colors  are  metallic  oxides.  The  ground  oxide,  in  fine  pow- 
der, is  intimately  mixed  with  gum  water,  acid  of  tar,  oil  of  turpentine, 
or  some  other  essential  oil,  and  after  the  color  is  laid  on,  the  fluid  is 
entirely  evaporated.  The  colors  employed  are  the  same  as  those 
mentioned  under  glass. 

*  Trial  pieces  are  withdrawn,  from  time  to  time,  to  enable  the  manufacturer  to 
judge  of  the  state  of  the  ware. 

t  This  is  a  part  of  a  very  instructive  collection,  containing  a  complete  suite  of  all 
the  materials  used  in  the  manufacture  of  French  porcelain,  and  in  all  their  stages  of 
preparation  and  fabrication,  from  the  decomposed  granite,  up  to  the  perfect  vessel ;  em- 
bracing also  a  series  of  colors,  applied  upon  the  porcelain,  and  accompanied  by  ex- 
planatory and  descriptive  catalogues.  It  was  presented  to  me  by  Mr.  Alexander 
Brongniart,  the  superintendant  of  the  manufactory,  a  gentleman  well  known  for  his 
valuable  researches,  and  excellent  works  in  mineralogy  and  geology. 

37 


£90  EARTHS. 

Very  beautiful  designs  are  now  fixed  upon  the  common  ware  by 
&id  of  the  copperplate  printing  press.  The  design,  first  painted,  and 
then  engraved  upon  copper,  is  printed  with  a  metallic  color,  mix- 
ed with  prepared  linseed  oil,  upon  silver  paper,  which,  with  the  figure 
upon  it,  is  immediately  applied  to  the  biscuit,  and  then  rubbed  with 
a  hard  roll  of  flannel,  to  make  it  adhere,  and  after  about  an  hour,  the 
article  is  immersed  in  water,  which  softens  the  paper,  so  that  it  is  easily 
removed,  and  leaves  the  colored  figure  ;  the  piece  is  next  heated 
moderately  in  an  oven,  to  dissipate  the  oil,  and  is  then  prepared  to 
receive  the  glaze. 

The  porcelain  is  not  always  painted  in  the  biscuit ;  sometimes  it  is 
painted  on  the  glazing,  and  I  believe  this  is  generally  done,  on  the 
most  beautiful  porcelain ;  it  is  then  necessary  to  heat  the  vessels  again, 
in  the  enameller's  oven,  that  the  coloring  matter  may  be  melted,  and 
incorporated  with  the  glazing. 

Glazing. — To  prevent  the  absorption  of  fluids,  and  to  make  the  ves- 
sels more  cleanly,  they  are  covered  with  a  vitreous  coat,  a  thin  glassy 
film,  which,  as  long  as  it  lasts,  protects  the  ware  below.  In  the  case 
of  the  common  stone  ware,  it  is  produced  by  throwing  into  the  hot 
furnace,  common  salt,  which  is  raised  in  vapor,  by  the  heat,  when  the 
soda  vitrifies  the  outside  and  forms  a  perfect  covering,  which  is  also 
safe  and  cheap. 

The  glazing,  used  on  the  common  yellow  ware,  is  composed  of  40 
pounds  of  ground  flints,  and  100  of  litharge,*  or  of  100  of  litharge, 
and  80  of  Cornish  granite. 

For  porcelain  and  the  finer  kinds  of  earthen  ware,  it  is  composed  of 
white  lead,  ground  flint  glass,  ground  silex,  and  common  salt, 

The  materials  of  the  glaze  are  reduced  to  an  impalpable  powder, 
and  suspended  by  agitation  in  water ;  the  vessels  are  dipped  in  them, 
and  they  retain  enough  to  form  a  perfect  covering  when  they  are 
again  exposed  to  the  heat  of  the  furnace.  This  glazing  is  dangerous  5 
on  account  of  the  poisonous  nature  of  lead  :  lava  and  pumice  stone, 
have  been  substituted  in  France  with  good  success  ;  and  even 
ground  flint  glass,  mixed  with  clay  and  water,  has  been  found  to  an- 
swer |  indeed,  no  protection  would  be  better  than  the  common  mate- 
rials of  glass,  was  not  the  ratio  of  its  contraction  and  expansion  by 
heat,  different  from  that  of  pottery,  which  would  cause  it  to  break. 
Metals  and  their  oxides  are  sometimes  mingled  with  the  materials  of 
the  glaze,  to  give  it  color,  in  certain  parts,  as  on  the  edges  of 
plates,  copper  being  used  for  green,  and  manganese  for  black. 

Porcelain  is  occasionally  covered  with  gold  or  platinum  in  sub- 
stance. The  gold  is  dissolved  in  nitro-muriatic  acid,  which  is  evap- 
prafed,  leaving  the  metal  in  a  state  of  minute  division  ;  it  is  next  mix-- 

The  French  use  galena,  the  native  sulphuret  of  lead,  thence  called  potter"* 


EARTHS.  £9  i 

ed  with  borax4  and  gum  water,  and  by  means  of  a  volatile  oilj  applied 
to  the  article  ;  it  is  then  baked,  and  afterwards  burnished. '  The 
lustre  ware  is  made  by  applying  an  oxide  of  gold,*  with  a  volatile 
oil,  which  is  laid  upon  the  vessels,  colored  by  umber  or  red  clay  ; 
this  appears  through  the  gold,  and  gives  the  copper  tint.  The 
steel  colored  ware  is  covered  with  the  precipitate  by  muriate  of 
ammonia,  from  the  muriate  of  platinum,  which  is  applied  in  a  similar 
way,  but  upon  a  cream  colored  basis  ;  and  in  both  cases,  it  is 
introduced  into  the  enameller's  oven,  where  the  heat  dissipates  the 
volatile  principles,  and  the  metals  being  left  in  their  dull  state,  are 
afterwards  burnished. 

The  ware  is  glazed  before  the  gold  and  platinum  are  applied. 

When  prints  are  made  to  adhere  to  the  biscuit,  in  the  manner  al- 
ready described,  as  the  glaze  is  applied  afterwards,  it  is  important  that 
it  should  be  transparent,  that  the  colors  may  be  seen  through  it. 

It  should  be  mentioned  that  the  glazing  on  the  best  porcelain,  par- 
ticularly that  of  China,  is  composed  entirely  of  feldspar,  finely  pulver- 
ized, and  suspended  in  an  aqueous  fluid^  which  is  said  to  be  in  China,- 
a  lye  of  fern  ashes  ;  no  lead,  or  other  metallic  matter,  enters  into  its 
composition,  and  it  requires  a  very  great  heat  to  produce  its  fusion ; 
it  is  much  harder  than  the  glaze  on  most  European  porcelain. 

The  Chinese  ware  is  made  so  firm  that  it  is  merely  dried  before 
dipping  it  into  the  glaze,  and  does  not  require  a  previous  baking  ta- 
bling it  to  the  state  of  biscuit. 

In  general,  the  European  porcelain,  although  superior  to  the  Ori- 
ental in  whiteness  and  beauty,  and  in  its  exquisite  ornaments,  is  in- 
ferior in  hardness,  infusibility,  weight,  capability  of  enduring  sudden 
changes  of  temperature,  and  in  the  permanency  of  its  glazing.  Some 
of  the  Saxon  porcelain  is  said  to  be  equal  to  the  Chinese. 

Crucibles  are  made  of  the  most  infusible  ckys,  arid  pipes  and  tiles 
are  manufactured  upon  similar  principles  with  those  that  have  been 
explained. f 

Bricks,  of  every  variety,  are  merely  rude  pottery. 

Fire  Bricks  are  made  of  very  refractory  clay,  called  fire  clay,  and 
are  both  more  infusible  and  worse  conductors  of  heat  than  common 
bricks.  They  are  sometimes  prepared  so  as  to  be  soft,  or  capable 
of  being  cut,  in  order  that  they  may  be  adapted  to  different  purposes,- 
and  the  fire,  as  they  are  used,  hardens  them  afterwards  5  at  other 
times  they  are  burned  hard  at  first*  Those  manufactured  at  New 


*  A  private  letter  to  the  author  from  Mr.  Accum,  in  1809,  mentioned,  that  fulmina-* 
ting  gold  was  applied  in  this  way ;  if  so,  doubtless  its  explosive  character  was  de- 
stroyed by  the  combustible  matter  of  the  oil  of  spike,  with  which  it  was  said  to  be 

t  See  Parkes'  Essays,  Vol.  II ;  Gray's  operative  Chemist,  and  Bigelow's  Tech- 
nology. 


292  EARTHS. 

Haven  are  made  by  using  a  fire  clay,  brought  from  Amboy,  and 
found  near  the  pipe  clay  ;  an  equal  measure  of  rather  coarse  silice- 
ous sand  is  added,  and  they  are  baked  in  a  potter's  oven,  with 
less  heat  than  is  employed  for  stone  ware.  Such  bricks  endure  the 
intense  heat  raised  in  the  cylindrical  furnace  stoves,  in  which  the 
anthracite,  and  particularly  the  Lehigh  coal  is  burned.  On  the  side 
exposed  to  the  fire,  they  become  vitrified,  and  the  impurities  of  the 
coal,  consisting  of  earths,  and  oxide  of  iron,  attach  themselves  to  the 
bricks,  in  the  form  of  a  slag,  and  if  the  accumulated  matter  is  not 
frequently  detached,  it  eventually  chokes  the  furnace. 

The  common  bricks  are  burned  in  huge  piles,  called,  in  this  coun- 
Iry,  Kilns,  in  England,  Clamps.  They  are  constructed  of  the 
moulded  and  sun-dried  bricks,  laid  up  with  interstices,  for  the  flame 
and  hot  air,  and  there  are  cavities  left  at  the  bottom,  crossing  the 
structure,  in  an  arched  form ;  in  these  the  dried  wood  is  laid,  and 
the  fire  being  kindled,  is  gradually  increased,  for  the  first  twelve 
hours,  after  which  it  is  kept  at  a  uniform  height  for  several  days  and 
nights,  until  the  bricks  are  sufficiently  hardened.  Some  are  exter- 
nally vitrified,  or  covered  with  a  glaze,  which  is  nothing  but  the 
melted  materials  of  the  bricks,  and  is  not  desirable,  as  good  bricks 
can  be  made  without  vitrification.  Some  bricks  are  soft,  and  ab- 
sorbent of  water,  and  will  split  with  the  frost :  others  are  firm,  and 
will  endure  a  great  length  of  time.  There  is  a  great  diversity  in  the 
elays  of  different  places,  as  regards  the  goodness  of  the  bricks  made 
from  them.  Bricks,  after  being  partially  dried  in  the  sun,  are  some- 
times pressed  hi  iron  machines,  which  forces  out  water  and  air,  and 
makes  them  more  firm  and  handsome. 

Terracotta,  or  Terre  cuite,  (burnt  earth,)  is  used  by  the  moderns, 
as  it  was  by  the  ancients,  in  making  ornamental  designs,  "  vases, 
imitations,  and  architectural  decorations. n  The  finer  kinds  of  clay 
are  employed,  and  they  are  with  great  facility  moulded  into  any  de- 
sired form. 

Reamur's  Porcelain* — This  curious  production  might  have  been 
mentioned  under  glass,  of  which  it  is  only  an  alteration,-  effected  by 
the  action  of  continued  heat  to  the  point  of  softening,  and  followed 
by  slow  cooling,  when  the  glass  loses  its  transparency,  and  under- 
goes a  kind  of  crystallization.  The  change  is  most  easily  effected 
upon  green  bottle  glass ;  it  is  found  to  be  owing  to  the  loss  of  the 
alkali  by  the  heat,  and  that  the  glass  thus  changed  will  endure  sud- 
den changes  of  temperature,  as  well  as  the  best  porcelain.  It  is 
usually  prepared  by  filling  a  common  green  glass  bottle  with  white 
sand  and  gypsum ;  it  is  buried  and  pressed  down  in  this  mixture,  in 
a  covered  and  luted  crucible,  and  baked  in  a  potter's  kiln,  during 
the  usual  time  of  firing  the  ware,  at  the  end  of  which  period,  it  will 
be  found  changed  into  a  kind  of  porcelain. — Bigelow's  Tech. 


EARTHS.  293 

ALUMINIUM.* 

1.  HISTORY. 

(a.)  Discovered  by  Sir  H.  Davy,  who  obtained,  by  galvanic  pow- 
er, a  compound  of  iron  and  this  metallic  base,  which  effervesced  in 
water,  and  produced  alumina,  and  oxide  of  iron ;  also,  by  passing 
potassium,  in  vapor,  through  alumina  heated  to  whiteness,  the  potassi- 
um was  converted  into  potash,  and  metallic  particles  were  obtained, 
which  became  white  in  the  air,  and  effervesced  in  water  ;  when  the 
temperature  was  only  at  a  red  heat,  an  alloy  of  the  two  metals  ap- 
peared to  be  obtained,  which  effervesced  violently  in  water,  and  took 
fire  spontaneously  in  the  air. 

2.  NEW  PROCESS. 

(a.)  Of  late,  Dr.  JVohler  has  obtained  aluminium  pure. ^ — (The 
student  may  omit  this  process  until  he  has  studied  chlorine.)  Chlo- 
ride of  aluminium  is  formed  by  passing  dry  chlorine  gas  through  an 
ignited  porcelain  tube,  containing  very  dry  alumina,  intimately  blend- 
ed with  charcoal,  in  consequence  of  its  having  been  mixed  in  the 
state  of  hydrate,  and  then  ignited  in  a  covered  crucible,  with  char- 
coal, sugar,  and  oil  5  the  hydrate  is  made  by  adding  an  excess  of 
carbonate  of  potash,  to  a  hot  solution  of  alum. 

(b.)  Carbonic  oxide  gas  ivas  evolved,  and  after  the  chlorine  gas 
had  passed  for  an  hour  and  a  half,  the  sublimed  chloride  of  alumini- 
um had  collected  in  such  quantity  as  to  choke  the  tube. 

(c.)  The  chloride  was  in  greenish  yellow  translucent  scales,  resem- 
bling  talc,  deliquescing  into  a  clear  liquid,  and  combining  with  waterr 
with  heat,  and  even  ebullition,  if  the  quantity  of  water  was  small, 
and  muriate  of  alumina  was  formed. 

(d.)  Potassium  decomposes  the  chloride  of  aluminium,  and  evolves 
the  metal. — »The  action  is  too  violent  for  glass,  which  is  [destroyed 
by  the  heat  disengaged.  It  succeeds  in  a  platinum  crucible,  the 
cover  being  secured  by  wire,  and  the  heat  of  a  spirit  lamp  applied  } 
but  the  crucible  becomes  red  hot.} 

(e.)  The  potassium  should  be  free  from  carbon,  and  the  quantity 
not  over  the  size  of  ten  peas>  and  so  proportioned,  that  none  of  the 
chloride  may  sublime,  during  the  decomposition,  nor  the  resulting 
mass  be  alkaline. 


*  Aluminum  would  seem  preferable,  but  I  adopt  the  orthography  already  intro- 
duced. 

i  The  first  hint  was  given  by  Prof.  Oersted,  in  consequence  of  his  having  obtain- 
ed what  he  believed  to  be  aluminium,  by  acting  upon  chloride  of  alumina,  by  an 
amalgam  of  potassium. 

t  To  prevent  the  possibility  of  deception,  the  experiment  was  repeated  in  a  porce- 
lain crucible,  and  with  complete  success. 


294  EARTHS. 

(/.)  The  mass  in  the  crucible  is  found  to  be  melted,  and  of  a  dark 
gray  color,  and  when  put  into  water  after  it  is  cold,  the  saline  matter 
is  dissolved,  an  offensive  hydrogen  gas  is  evolved,  and  metallic  scales 
remain,  which  after  being  thoroughly  washed  in  cold  water,*  are  pure 
aluminium. 

3.  PROPERTIES; 

(a.)  A  gray  powder  very  simitar  to  that  of  platinum,  in  small  me- 
tallic scales  or  spangles,  or  in  slightly  coherent  spongy  masses,  hav- 
ing in  some  places  a  tin  white  lustre,  rendered  more  distinct  by  pres- 
sure on  steel,  or  in  an  agate  mortar. 

(b.)  In  fine  powder,  a  non-conductor  of  electricity,  but  becomes  a 
conductor  after  fusion, f 

(c.)  Fusible  at  a  higher  heat  than  that  which  melts  cast  iron. 

(d.)  Ignited  in  the  air,  it  burns  vividly,  and  the  product  is  alu- 
minous earth,  white  and  considerably  hard ;  sprinkled  in  powder,  in 
the  flame  of  a  candle,  it  gives  bright  scintillations,  like  iron  in  oxygen 
gas. 

(e.)  Ignited  in  pure  oxygen  gas,  it  burns  with  great  heat  and  light, 
and  the  resulting  alumina  is  partially  vitrified,  yellowish,  and  hard  as 
corundum  ;  it  even  cuts  glass.  When  burning  in  glass,  it  appeared 
to  reduce  the  silicium,  producing  a  semi-fused  brown  spot. 

^/.)  Near  ignition,  it  burns  in  chlorine  gas,  and  chloride  of  alu- 
minium is  formed. 

(g.)  Not  oxidized  nor  tarnished  by  cold  water ;  near  ebullition, 
hydrogen  gas  is  feebly  evolved,  and  scarcely  any  oxidizement  is  ob- 
served. 

(h.)  No  action  with  strong  sulphuric  or  nitric  acid  in  the  cold, 
but  with  heat,  the  former  is  decomposed,  and  sulphurous  acid  gas 
evolved ;  it  is  dissolved  in  dilute  muriatic  and  sulphuric  acid,  and 
hydrogen  gas  extricated. 

(i.)  Dissolved  readily  and  entirely  in  dilute  solution  of  potash, 
and  even  in  ammonia,  hydrogen  gas  being  evolved,  and  much  alu- 
mina held  in  solution.j 

4.  COMBINING  WEIGHT. — Not  accurately  ascertained  ;  it  has  been 
already  stated,  that  the  number  10  has  been  adopted,  and  that  it 
combines  with  one  proportion  of  oxygen,  8,  to  form  alumina,  whose 
equivalent  is  of  course,  18* 


*  The  solution  is  neutral,  and  contains  some  alumina,  formed,  as  it  is  said,  in  con- 
sequence of  a  combination  between  chloride  of  potassium,  and  chloride  of  aluminium. 

t  It  is  remarkable,  as  Dr.  Wohler  observed,  that  metallic  iron,  in  fine  powder,  is 
a  non-conductor  of  electricity,  so  that  this  property  of  metals  seems  to  depend  on 
their  form,  or,  possibly,  on  intervening  air.  Perhaps  if  silicium  were  melted,  it 
might  become  a  conductor,  and  thus  be  assimilated  to  the  metals. 

J  Dr.  Brewster's  Journal,  No.  17,  p.  178. 


EARTHS'.  295 

5.  POLARITY. — Electro-positive,  as  appears  from  the  original  ex- 
periment of  Sir  H.  Davy,  in  which  it  was  attracted  to  an  iron  wire 
connected  with  the  negative  pole  of  the  galvanic  series. 

Remark. — That  alumina  so  extensively  diffused  and  so  familiarly 
known,  should  contain  a  metal,  distinct  and  remarkable  in  its  pro- 
perties, and  with  the  aid  of  potassium,  so  easily  obtained,  is  a  very 
interesting  confirmation  of  the  views  of  the  illustrious  Davy,*  and  must 
give  celebrity  to  that  of  Dr.  Wohler. 

Should  the  basis  of  the  most  important  of  the  earths,  namely,  si- 
licium,  which  Prof.  Berzelius  has,  by  the  aid  of  the  same  agent, 
potassium,  now  placed  fully  within  our  reach,  eventually  prove,  after 
fusion,  to  be  truly  metallic,  it  would  be  an  interesting  addition  to  the 
series  ;  but  in  any  event,  the  great  fact  that  the  earths  are  all  oxides, 
is  sufficiently  established. 

SEC.  VII.— ZIRCONIA. 

1.  NATURAL  HISTORY  AND  DISCOVERY. 

Never  found  pure  in  nature;  discovered  first  in  1789,  by  Klap-< 
roth,  in  the  jargon  or  zircon,  a  precious  stone  from  Ceylon,  in  which 
he  found  37.5  silica,  .5  nickel  and  iron,  and  68.  of  the  new  earth, 
which  from  its  parent  mineral,  he  called  zirconia.  In  1795,  found 
by  him  in  the  hyacinths  of  Ceylon,  and  in  1796,  discovered  by  Mor- 
veau,  in  those  from  the  brook  of  Expailly,  in  France  ;  Vauquelin 
confirmed  the  discovery  by  farther  experiments, f 

2.  PROCESS. 

(a.)  To  the  pulverized  zircon,  add  three  or  four  times  its  weight,  J 
of  caustic  potash,  and  fuse  it  in  a  silver  crucible,  throwing  in  the  mix- 
ture, spoonful  by  spoonful,  and  waiting  for  the  fusion  of  each  portion 
before  another  is  addedt  and  after  all  are  fused,  increase  the  heat  and 
maintain  it  for  an  hour  and  a  half.  Wash  the  contents  of  the  cru- 
cible abundantly  in  boiling  hot  water,  to  remove  the  alkali.  Now 
add  muriatic  acid  to  dissolve  the  zirconia,  some  silica  is  taken  up  by 
the  acid,  which  is  precipitated  by  heating  the  fluid,  and  removed  by 
filtration.  Lastly,  add  potassa ;  the  zirconia  precipitates ;  or  it  may 
be  thrown  down  by  carbonate  of  soda,  and  must  then  be  washed 
sufficiently  with  pure  water. 


*  Whose  premature  death,  the  friends  of  science  and  mankind  will  long  deplore. 

t  Dr.  Thomson,  of  Glasgow,  has  discovered  18  per  cent,  of  zirconia,  in  the  Silli- 
manite,  a  new  prismatic  mineral  species  fpund  at  Chester,  in  Saybrook,  Conn,  and 
first  analyzed,  named,  and  described  by  the  late  Prof.  Bowen,  who  found  it  to  consist 
of  alumina,  54.11,  silica,  42.66,  iron,  1.99,  and  water  .51.  Dr.  Thomson  found  a  sim- 
ilar constitution,  except  that  he  discovered  the  zirconia  as  above  stated.— Am.  Jour. 
Vol.  VIII,  195.  217;  Vol.  XII,  159,  and  Vol.  XVI,  207. 

t  Five  or  six  times,  Four.  II,  210— nine  times,  Ure's  Pict.  815. 


296  EARTHS. 

(b.)  Or,  to  1  part  powdered  zirconia,  add  2  of  potassa,  and  heat  it  for 
one  hour  in  a  silver  crucible  ;  add  distilled  water,  filter  and  wash  well 
the  insoluble  part,  which  will  be  a  compound  of  zirconia,  silica,  potash 
and  oxide  of  iron.  Dissolve  in  muriatic  acid,  and  evaporate  to  dry- 
ness,  to  separate  the  silica.  Redissolve  the  muriates  of  zirconia  and 
iron  in  water,  and  having  washed  the  remaining  silica  with  weak  mu- 
riatic acid,  to  remove  any  adhering  zirconia,  add  it  to  the  fluid.  Fil- 
ter and  precipitate  tlie  zirconia  and  iron  by  pure  ammonia ;  wash 
the  precipitates  well,  and  then  boil  them  in  oxalic  acid ;  this  dis- 
solves the  iron  and  leaves  the  zirconia  an  insoluble  oxalate,  which  is 
to  be  washed  until  no  more  iron  can  be  detected  in  the  washings. 

The  oxalate  of  the  earth,  which,  when  dry,  is  of  an  opaline  color,* 
is  then  to  be  decomposed  by  heat  in  a  platinum  crucible. f 

3.  PROPERTIES. 

(a.)  A  fine  white  powder,  tasteless  and  inodorous,  resembles  alu- 
mina, but  somewhat  harsh  to  the  touch ;  sp.  gr.  after  being  heated  vi- 
olently on  charcoal,  4.3. 

(b.)  Infusible  before  the  common  blowpipe,  but  heated  in  a  char- 
coal crucible  protected  by  an  earthen  one,  in  a  good  forge  fire,  for 
some  hours,  becoming  a  substance  like  porcelain,  insoluble  in  acids, 
suffering  a  partial  fusion,  and  acquiring  a  gray  color.  In  this  state, 
it  will  scratch  glass — gives  fire  with  steel,  and  has  the  specific  gravity 
of  4.3. 

(c.)  Perfectly  fusible  before  the  compound  blowpipe  of  Dr.  Hare, 
producing  a  white  enamel.f 

(d.)  Insoluble  in  water,  but  is  absorbent  of  it,  and  when  dried 
slowly  after  being  precipitated  form  a  solution,  it  has  a  yellow  color ; 
retains  about  one  third  of  its  weight  of  water ;  has  a  small  degree  of 
transparency,  and  resembles  gum  arabic.  When  heated  red  in  a  cru- 
cible of  silver,  it  loses  .37  of  its  weight. 

(e.)  No  action  on  combustibles,  or  oxygen,  or  nitrogen. 

(f.}  Insoluble  in  alkalies,  but  dissolved  in  alkaline  carbonates. 

(g.)  Insoluble  in  acids,  until  it  has  been  acted  upon  again  by 
caustic  potash,  and  washed  till  the  alkali  is  removed  ;  it  is  next  dis- 
solved in  muriatic  acid,  precipitated  by  ammonia  and  the  washed  hy- 
drate,§  is  then  easily  soluble  in  acids,  forming  salts,  and  those  with 
the  sulphuric,  carbonic,  and  phosphoric  acids,  are  insoluble  in  water. 
In  general,  the  salts  of  zirconia  are  insoluble,  and  those  that  are  solu- 
ble, have  a  sweetish  astringent  taste. 


*  For  a  third  process,  see  Thenard,  Vol.  II,  p.  295,  and  Ann.  de  Chim.  et  de  Phys. 
T.  XIII,  p.  245. 

t  Ann.  de  Chim.  et  de  Phys.  T.  XIV,  p.  110. 

t  Am.  Jour.  Vol.  II,  p.  292. 

§  The  hydrate  heated  by  a  spirit  lamp  in  a  glass  capsule,  becomes  red  hot,  as 
if  it  were  on  fire. — Thenard. 


EARTHS.  297 

(A.)  Zirconia  differs  from  silica,  in  being  much  more  soluble  in 
acids,  and  in  being  insoluble  in  alkalies,  but  it  is  soluble  in  alkaline 
carbonates ;  in  this  last  property  it  differs  from  alumina  and  glucina. 

(«'.)  There  is  a  great  resemblance  between  oxide  of  titanium  and 
zirconia,  in  most  of  their  properties ;  but  tincture  of  galls  precipi- 
tates oxide  of  titanium  reddish  brown — zirconia  in  yellow  flocks.* 

4.  POLARITY. — From  analogy,   supposed  to  be  electro-positive; 
and  to  be  attracted  to  the  negative  pole  of  the  galvanic  series. 

5.  COMBINING  WEIGHT,  48,  consisting  of  zirconium,  1  proportion, 
40,  and  oxygen,  1  proportion,  8. — Thomson.     It  has  been  supposed 
from  some  experiments  of  Berzelius,  that  it  is  30  or  33. 

ZIRCONIUM. 

1.  HISTORY  AND  PROCESS. 

Sir  H.  Davy  discovered,  that  when  zirconia  is  ignited  with  po- 
tassium, the  latter  is  oxidized,  and  dark  metallic  particles  are  diffused 
through  the  alkali. 

Berzelius  has  more  recently  procured  this  base,  as  he  did  sili- 
cium ;  that  is,  by  heating  with  a  spirit  lamp,  in  a  tube  of  glass  or  iron, 
a  mixture  of  potassium  and  hydro-fluate  of  zirconia  and  potassa,  care- 
fully dried ;  at  a  temperature  below  ignition,  the  earth  is  reduced  to 
the  metallic  state,  and  without  any  luminous  appearance ;  the  mass  is 
next  washed  with  boiling  water,  and  then  digested  for  some  time  in 
pure  muriatic  acid ;  the  residue  is  pure  zirconium,  f 

2.  PROPERTIES. 

(a.)  Black  as  charcoal;  it  is  a  powder. 

(6.)  Not  oxidized  by  boiling  water,  or  sulphuric  or  muriatic  acid, 
but  dissolved  by  aqua  regia,  and  hydro-fluoric  acid,  the  latter  evolv- 
ing hydrogen. 

(c.)  Zirconium  burns  intensely  in  the  open  air,  with  a  slight  in- 
crease of  heat,  but  far  below  luminousness,  and  produces  zirconia. 

(d.)  It  combines  with  sulphur,  forming  a  chesnut  brown  sulphuret, 
insoluble  in  muriatic  acid,  and  alkalies  ;  but  which  burns  brilliantly, 
regenerating  the  earth,  and  evolving  sulphurous  acid.J 

(e.)  Does  not  conduct  electricity ;  it  is  capable  of  being  pressed 
out  into  scales  of  a  dark  gray  color,  having  somewhat  of  the  metal- 
lic appearance,  but  it  is  not  perfectly  settled  whether  it  ought  to  be 
called  a  metal. 

3.  COMBINING  WEIGHT — not  accurately  determined.    See  zirco- 
nia, 5. 


*  Ann.  of  Philos.  XIII,  83.  »  Turner,  and  Eng.  Quar.  Jour.  XV111, 157. 

t  Ann.  of  Philos.  N.  S.  VIII,  123. 

38 


298  EARTHS. 

SEC.  VIII.— GLUCINA. 

1.  NAME — NATURAL  HISTORY — DISCOVERY. 

From  /Xuxuj,  sweet,  because  its  salts  have  that  taste.  Discovered 
in  the  beryl  and  emerald,  in  1798,  by  Vauquelin,  who  at  the  request 
of  Haiiy,  analyzed  the  beryl  to  discover  whether  its  chemical  in- 
gredients were  the  same  with  those  of  the  emerald,  as  from  physical 
considerations,  he  had  conjectured  that  they  were.  The  analysis 
proved  the  suspicions  of  Haiiy  to  be  well  founded. 

2.  PROCESS. — (Th.  I,  530.)     Fuse  pulverized  emerald  or  beryl 
1  part,  with  potassa  3  parts  ;  dilute  the  mass  with  water,  dissolve  in 
muriatic  acid,  and  evaporate  to  dryness,  stirring  the  matter  towards 
the  end.     Mix  it  with  much  water,  and  filter  to  separate  the  silica, 
which  is  more  than  half.     The  muriates  of  glucina  and  alumina  are 
in  solution ;  precipitate  them  by  carbonate  of  potash,*  wash  the  pre- 
cipitate, and  dissolve  it  in  sulphuric  acid.     Add  to  the  solution  sul- 
phate of  potash ;  evaporate  and  obtain  crystals  of  alum.     When  no 
more  are  formed  by  adding  sulphate  of  potash,   add  carbonate  of 
ammonia  in  excess,  shake  the  mixture,  and  let  it  stand  till  the  gluci- 
na is  dissolved  by  the  carbonate  of  ammonia,  and  nothing  but  alumina 
is  left,  then  filter,  and  evaporate  to  dryness,  when  a  white  powder  is 
obtained,  which,  after  slight  ignition  in  a  crucible,  is  glucina,  in  the 
proportion  of  16  per  cent,  of  the  stone.     Euclase  also  contains  21.78 
of  this  earth ;  and  by  Mr.  Seybert's  analysis,  the  chrysoberyl  of  both 
Haddam  and  Brazil,  has  as  much  as  the  emerald, f  that  is  15.80 
glucina  for  the  chrysoberyl  of  Haddam,  and    16,  for  that  of  Brazil ; 
the  other  constituents  were  for  the  latter,  alumina  68,66,  silica  5.99, 
oxide  of  titanium  2.66,  oxide  of  iron  4.73,  and  water ;  for  that  of 
Haddam,  73.66  alumina,  4  silica,  1  oxide  of  titanium,  3.38  oxide  of 
iron,  and  a  little  moisture.     The  existence  of  glucina  in  chrysoberyl 
had  been  overlooked  by  the  first  analysts,  until  it  was  discovered  by 
Mr.  Seybert. 

3.  PROPERTIES. 

(a.)  Inodorous,  tasteless,  and  insoluble  in  water ;  but  forms  with 
it  a  paste  of  some  tenacity.  It  is  a  fine  white  powder,  resembling 
alumina,  and  like  that  adheres  to  the  tongue. 

b.)  Does  not  contract  in  the  fire,  nor  affect  the  test  colors. 

c.)  Specific  gravity  3. 

d.)  Infusible  by  the  common  blow  pipe,  but  perfectly  fusible  by 
that  of  Dr.  Hare. 

*  The  latter  part  of  this  process  may  be  conducted  differently  from  the  descrip- 
tion in  the  text.  After  precipitating  the  alumina  and  glucina,  dissolve  them  in  water 
acidulated  by  muriatic  acid,  and  precipitate  again  by  pure  ammonia;  then  dissolve 
this  in  carbonate  of  ammonia,  and  proceed  to  the  end  as  already  directed.  Or,  start- 
ing from  the  same  point:  add  to  the  precipitated  earths  pure  potassa,  which  will  dis- 
solve the  alumina,  and  a  portion  of  the  glucina,  but  that  which  remains,  is  this  earth 
sometimes  slightly  colored  by  iron.  For  the  mode  of  extracting  glucina  from  the 
chrysoberyl,  see  Am.  Jour.  Vol.  Vill,p.  105.  I  Am.  Jour.  Vol.  Vlll,  p.  105, 


EARTHS.  299 

(e.)  Combines  with  potassa  and  soda,  but  not  with  ammonia,  al- 
though it  is  soluble  in  the  carbonate  of  that,  and  of  other  alkalies,  and 
in  the  caustic  fixed  alkalies. 

(/*.)  With  all  the  acids  forms  salts,  with  a  sweetish  astringent  taste  ; 
they  are  decomposed  by  the  alkalies,  even  by  ammonia,  which  does 
not  precipitate  alumina,  which  glucina  considerably  resembles. 

(g.)  Resembles  alumina  in  attracting  coloring  matter. 

(A.)  It  is  not  precipitated  by  prussiate  of  potash. 

(i.)  It  absorbs  carbonic  acid,  at  the  ordinary  temperature  of  the 
air. 

4.  COMBINING  WEIGHT. — Stated  by  Dr.  Thomson,  and  by  Ber- 
zelius  as  26. 

5.  POLARITY. — From  analogy  supposed  to  be  electro  positive. 

GLUCINIUM. 

1.  This  base  has  not  been  distinctly  obtained,  but  the  analogy 
which  would  lead  us  to  admit  its  existence,  is  strongly  supported  by 
the  following  fact. 

2.  Sir  H.  Davy  ascertained  that  by  igniting  potassium  with  glu- 
cina, the  metal  is  converted  into  potassa,  thus  proving  the  existence 
of  oxygen  in  the  earth ;  dark  colored  particles,  with  a  metallic  aspect 
also  appeared  in  the  mass,  and  regained  the  earthy  character  by  be- 
ing heated  in  the  air,  and  by  the  action  of  water,  hydrogen  gas  being, 
in  the  latter  case,  evolved. 

3.  COMBINING  WEIGHT. — Dr.  Thomson  concludes  that  the  num- 
ber for  the  earth  must  be  26,  and  if  it  consists  of  1  proportion  of  me- 
tallic base,  and  1  of  oxygen,  the  latter  being  8,  the  former  will  of 
course  be  18.* 

4.  POLARITY. — Supposed  from  analogy  to  be  electro  positive. 

SEC.  IX.— YTTRIA. 

1.  NAME — NAT.  HISTORY — DISCOVERY. 

Name,  from  Ytterby,  a  quarry  in  Sweden,  where  the  mineral  was 
found,  from  which  Yttria  was  first  extracted. 

Discovered  by  Prof.  Gadolin,  in  1794,  during  his  analysis  of  this 
mineral,  called  after  him,  the  Gadolinite,  and  confirmed  by  several 
eminent  chemists  since. 

Yttria  has  been  found,  not  only  in  the  mineral  mentioned  above,-)" 
which  yielded  it  in  the  proportion  of  35  to  45  per  cent.,  but  also  in 
another  mineral,  consisting  of  the  metal  tantalum,  and  yttria,  called 
yttrotantalite,  containing  about  20  per  cent.,  and  in  the  yttrocerite, 
which  has  about  8  or  9  per  cent.  These  minerals,  as  well  as  Ga- 
dolinite are  found  only  in  the  quarry  of  Ytterby. 

2.  PROCESS. 


*  Thomson's  First  Principles,  Vol.  I,  p.  318. 
t  Combined  with  black  oxide  of  iron  and  silica. 


300  EARTHS. 

(a.)  *Let  the  Gadolinite  be  repeatedly  digested  in  muriatic  acid, 
and  silica  remains.  To  the  fluid,  add  liquid  ammonia,  boil  the  pre- 
cipitate in  solution  of  potash,  and  filter.  Dissolve  the  insoluble  resi- 
due of  the  last  process  in  diluted  sulphuric  acid,  evaporate  to  dry- 
ness,  ignite,  and  redissolve  it  in  water  ;  a  precipitate  falls  down,  which 
must  be  separated  by  the  filter. 

The  filtered  solution,  when  mingled  with  liquid  ammonia,  yields  a 
precipitate  which  is  Yttria.f 

(b.)  Fuse  the  Gadolinite  1  part,  with  caustic  potash  2,  wash  the 
mass  with  boiling  water,  and  filter  the  liquor,  which  will  be  of  a  fine 
green ;  evaporate  till  the  oxide  of  manganese,  in  the  form  of  a  black 
powder,  ceases  to  fall ;  then  saturate  the  liquid  with  nitric  acid. 
Digest  the  undissolved  sediment  in  dilute  nitric  acid,  which  will  dis- 
solve the  earth  with  much  heat,  leaving  the  silica  undissolved,  and 
the  iron  highly  oxidized.  Mix  the  two  liquors,  evaporate  to  dryness 
and  redissolve  and  filter,  which  will  separate  any  silica  or  oxide  of  iron 
that  may  have  been  left.  A  little  carbonate  of  potash  will  separate 
any  lime,  and  hydro-sulphuret  of  potash  will  precipitate  any  mangan- 
ese ;  but  if  too  much  be  added,  it  will  throw  down  the  yttria  too. 
Lastly,  ammonia  will  precipitate  the  yttria,  which  must  be  well  wash- 
ed and  dried. } 

3.  PROPERTIES. 

(a.)  Ji  fine  white,  powder ',  infusible  alone,  but  with  borax  melts 
into  a  glass. 

(6.)  Tasteless,  smooth,  and  inodorus — no  effect  on  vegetable  colors. 

(c.)  Sp.  gr.  4.842,  greater  than  that  of  any  earth. 

(d.)  Insoluble  in  water,  but  absorbs  it,  and  loses  .31  of  its  weight 
when  heated  to  redness. 

(e.)  Soluble  in  alkaline  carbonates,  but  not  in  pure  alkalies,  like 
alumina  and  glucina ;  requires  to  dissolve  it  5  or  6  times  as  much 
carbonate  of  ammonia  as  glucina  does. 

(/.)  With  acids  forms  sweet  tasted  salts,  with  some  degree  of 
austerity,  and  several  of  them  are  said  to  be  colored,  a  fact  not  ob- 
served in  any  other  metallic  salts,  but  there  can  be  little  doubt  that 
the  color  is  owing  to  the  adhering  iron  and  manganese. 

(g.)  Solution  of  Yttria  in  muriatic  acid,  evolves  chlorine  after  be- 
ing long  heated. 

(A.)  Oxalic  acid,  and  oxalate  of  ammonia,  precipitate  yttria  like 
muriate  of  silver. 

4.  POLARITY. — Supposed  from  analogy  to  be  electro  positive. 

5.  COMBINING  WEIGHT,  42. 


*  Accum.  Mineral,  p.  137. 

t  For  the  process  of  Vauquelin,  see  Ann.  de  Chim.  p.  150,  XXXVI,  and  Henry, 
10th  Ed.  Vol.  I,  p.  625. 
J  Ure'sDict. 


EARTHS.  301 

YTTRIUM. 

1.  Not  yet  obtained  isolated. 

2.  Yttria  converts  potassium  into  potassa,  when  aided  by  heat,  thus 
proving  the  existence  of  oxygen  in  the  earth,  which  also  exhibits  ap- 
pearances of  metallization,  so  that  there  can  scarcely  be  a  doubt  that 
this  earth  consists  of  oxygen  and  inflammable  or  metallic  matter. 

3.  COMBINING  WEIGHT. — Dr.  Thomson  assigns  42  as  the  repre- 
sentative number  of  yttria,  and  supposing  that  the  earth  is  composed 
of  1  proportion   of  oxygen,  and  1   of  metal,  he  states  the  latter  at 
34,  for  34+8=42. 

#  #  *  *•  #  *•  # 

Since  the  account  of  the  earths  was  in  type,*  Prof.  Griscom  has 
been  so  kind  as  to  forward  to  me  the  following  notice  of  a  new  earth, 
which,  as  it  is  so  named  by  its  discoverer,  I  insert  here  rather  than 
under  the  metals.  The  learner  will  observe  that  it  is  a  different 
thing  from  the  substance  formerly  called  Thorina. — See  note,  p.  261. 

Discovery  of  a  new  earth,  named  Thorina,  and  its  metallic  base, 
named  Thorium. — M.  Dulong  communicated  to  the  Academy  of 
Sciences  at  Paris,  on  the  26th  of  July  last,  in  a  letter  from  M.  Ber- 
zelius,  the  discovery  of  a  new  earth.  "  I  have  just  discovered," 
says  the  Swedish  Savant,  "  a  new  earth,  which  possesses  almost  all 
the  properties  of  that  which  bore  the  name  of  Thorina,  and  which 
has  been  ascertained  to  be  only  a  phosphate  of  Yttria.  It  is  in  con- 
sequence of  this  striking  analogy,  that  I  have  retained  the  name  of 
Thorina,  for  this  new  substance.  This  earth  is  white,  and  irreduci- 
ble by  charcoal  and  potassium.  After  being  strongly  calcined,  it  is 
attacked  by  none  of  the  acids,  except  concentrated  sulphuric,  even 
after  being  treated  with  caustic  alkalies.  The  sulphate  of  Thorina 
is  very  soluble  in  cold  water,  and  almost  insoluble  in  boiling  water, 
so  that  it  may  be  freed  from  many  other  salts,  by  washing  the  mix- 
ture with  boiling  water.  Thorina  dissolves  easily  in  carbonate  of 
ammonia.  An  elevation  of  temperature  occasions  a  precipitation  of 
a  part  of  the  earth ;  but  on  cooling,  the  precipitate  disappears.  All 
the  salts  of  Thorina  have  a  very  pure  astringent  taste,  very  similar 
to  that  of  tannin.  The  chloride  of  Thorium,  treated  with  potassium, 
is  decomposed  with  a  triple  deflagration.  There  results  a  gray 
metallic  powder,  which  does  not  decompose  water,  but  which,  raised 
above  a  red  heat,  burns  with  a  splendor  almost  equal  to  that  of  phos- 
phorus in  oxygen  gas.  Nevertheless,  Thorium  is  feebly  attacked 
by  nitric  and  sulphuric  acids.  The  hydrochloric,  on  the  contrary, 
dissolves  it  with  a  brisk  effervescence.  Thorina,  or  the  oxide  of 
Thorium,  contains  11.8  oxygen.  Its  specific  gravity  is  9.4.  Tho- 
rina exists  in  a  new  mineral  which  has  been  found  in  very  small 
quantities  at  Brevig,  in  Norway. — Bib.  Univ.  Juillet,  1829. 

*  But  before  it  was  struck  off. 


302  INFLAMMABLES. 


SIMPLE  INFLAMMABLE  AND  ACIDIFIABLE  BODIES,   (not  metallic,)  AND 
THEIR  COMBINATIONS  WITH  THE  PRECEDING  BODIES. 

HYDROGEN SULPHUR CARBON PHOSPHORUS NITROGEN BO- 
RON  UNKNOWN   BASE    OF    FLUORIC    ACID SELENIUM. 

SEC.  I. — HYDROGEN. 

(a.)  This  inflammable  body  has  been  already  described  under 
the  head  of  water,  and  is  here  mentioned  again  only  for  the  sake  of 
classing  it. 

(b.)  With  oxygen,  it  forms  no  acid,  but  it  forms  one  with  chlorine, 
as  will  be  shewn  in  its  place. 

SEC.  II. — SULPHUR. 

•  1.  HISTORY. — Known  from  the  remotest  antiquity. 

2.  SOURCES. 

(a.)  Volcanos,  active,  dormant  or  extinct ;  sublimed  by  the  sub- 
terranean heat,  collects  in  craters  and  solfaterras,  as  near  Naples,  in 
Gaudaloupe,  &c. 

(b.)  Combined  with  metals,  forming  numerous  species  of  native 
sulphurets,  as  of  iron,  copper,  lead,  silver,  &ic.  sublimed  from  them 
by  artificial  heat,  but  is  not  in  this  manner  obtained  pure  ;  it  is  con- 
taminated with  the  metals,  with  which  it  was  combined. 

(c.)  In  sulphureous  mineral  waters — imparting  a  disgusting  odor, 
and  the  property  of  blackening  white  metals  and  their  solutions;  be- 
ing suspended  by  hydrogen,  it  is  deposited  as  that  gas  is  exhaled, 
and  is  found  in  the  channels,  through  which  the  waters  pass.* 

(d.)  In  animals  and  plants — found  more  or  less  in  all  animal  bo- 
dies, as  is  proved  by  the  production  of  sulphuretted  hydrogen,  dur- 
ing their  decomposition.  Among  plants,  in  the  rumices  or  docks, 
in  the  cruciform  plants,  as  scurvy  grass  and  cresses. 

Sulphur  was  sublimed  by  Deyeux,  from  roots  of  horse  radish  and 
of  dock.  J 

(e.)  In  rocks  and  stones,  along  with  gypsum  and  sulphate  of  stron- 
tia,  and  even  with  the  primitive  rocks  in  veins,  and  sometimes  in  in- 
durated marl  and  compact  limestone ;  arising  perhaps  from  the  de- 
composition of  sulphurets. 


*  At  Niagara,  it  oozes  from  the  bank  near  the  north  side  of  the  great  Horse  Shoe 
fall. — Own  observations,  Oct.  1827. 
I  Exists  in  eggs,  in  privies,  in  pits  in  which  flax  has  been  steeped,  &c. 


INFLAMMABLES.  303 

(/.)  In  sulphuric  acid,  forming  a  constituent  of  the  natural  sul- 
phates of  lime,  baryta,  strontia,  soda,  &c.  and  in  the  free  sulphuric 
and  sulphurous  acids. 

3.  PROPERTIES. 

(a.}  Sp.gr.  1.99. 

(b.)  Electric  by  friction  ;  color  lemon  yellow,  but  precipitated  sul- 
phur is  at  first  white,  and  it  becomes  white  if  water  be  dropped  on  it 
while  in  fusion,  and  also  if  sublimed  with  watery  vapor ;  the  whiteness 
is  supposed  to  be  owing  to  a  combination  with  water  ;*  electricity, 
negative  or  resinous  ;  a  non-conductor  of  heat.  Hence,  a  roll  of  it, 
grasped  in  the  hand,  crackles  in  consequence  of  its  brittleness,  and 
of  its  unequal  expansion  by  heat. 

(c.)  Emits  a  peculiar  odor  when  rubbed  or  heated. — Brittle  and 
fracture  brilliant ;  it  has  a  considerable  refractive  power. 

(d.)  Evaporates  at  170°,  with  a  disagreeable  smell ;  fuses  at  185° 
or  190°  ;  fluid  at  220°,  most  perfectly  fluid  between  230°  and  280°, 
when  it  is  of  an  amber  color. 

(e.)  It  begins  to  thicken  at  320°  ;  at  350°,  stiffens  and  acquires 
a  deeper  color ; f  is  very  tenacious  between  428°  and  482°,  but 
from  that  to  its  boiling  point,  it  grows  fluid  again,  and  on  cooling,  also, 
it  recovers  its  fluidity  ;  this  may  be  repeated  by  sudden  transitions  of 
temperature  in  close  glass  vessels ;  otherwise  the  sulphur  is  volati- 
lized. J 

Evaporates  at  290°  ;  it  can  be  distilled  from  a  glass  retort  into  a  re- 
ceiver. 

(/.)  Sublimes  at  600°. — The  sulphur  being  thrown  on  an  ignited 
iron,  and  covered  suddenly  with  a  bell  glass,  the  latter  is  instantly  lined 
with  the  sublimate  called  flowers  of  sulphur ;  melted,  skimmed,  de- 
canted, and  cast  in  moulds,  this  forms  the  best  roll  sulphur  .$ 


*  It  is  said  also  to  acquire  a  paler  color  from  adulteration  with  rosin,  flour,  &c. 

i  In  this  state,  or  when  heated  to  428°,  it  is  poured  into  hot  water,  and  is  used  to 
copy  medals,  they  being  impressed  upon  it  while  it  is  warm. 

I  Thenard,  I,  107,  quoted  by  Henry,  Vol.  I,  p.  380. 

§  Rough  sulphur  is  purified  by  melting  it  in  cast  iron  bodies  or  retorts,  covered 
with  earthen  ware  heads ;  about  six  cwt.  at  once,  and  the  distilled  sulphur  is 
drawn  off  into  water,  at  the  lower  of  three  holes  in  the  receiver;  one  being  for 
the  admission  of  the  retort,  and  one  for  the  escape  of  the  vapors ;  the  refined  sulphur 
is  cast  in  moulds  made  of  beech  wood.  In  subliming  sulphur,  the  furnace  is  below, 
and  the  sulphur,  melted  in  iron  pots,  rises  into  a  room  placed  above,  where  it  is  con- 
densed in  flowers  or  sublimate. 

It  is  sublimed  also  from  thick  iron  pots,  of  the  capacity  of  10  or  12  cwt.  by  a  lateral 
communication  from  its  dome  into  a  chamber,  which,  if  intended  for  roll  sulphur,  rnay 
be  not  more  than  one  fifth  the  size  that  would  be  requisite,  if  flowers  of  sulphur  were 
to  be  made. — Gray's  Op.  CJiem. 

If  the  distillation  is  rapid  and  incessant,  it  will  condense  in  the  liquid  form,  and 
will  be  made  into  roll  sulphur  ;  if  slow  and  with  suspension  at  night,  it  will  be  in  the 
form  of  flowers.  Formerly,  crude  sulphur  was  merely  melted,  and  when  the  impuri- 
ties had  subsided,  it  was  ladled  out  and  cast  in  moulds;  the  sulphur  thus  obtained 
was  impure,  and  much  was  lost  in  the  sediment;  the  best  roll  sulphur,  as  well  as 
flower:?,  has  been  distilled  or  sublimed. 


304  INFLAMMABLES. 

(g.)  In  the  arts,  to  form  the  flowers,  it  is  sublimed  in  rooms  lined 
with  sheet  lead. 

(h.)  Examined  by  the  test  fluids,  to  ascertain  whether  it  is  acid  ; 
agitate  it  with  infusion  of  cabbage  or  litmus. 

(i.)  Crystallization — natural  in  volcanos — often  beautiful  modi- 
fied octahedra ;  by  art — sulphur  melted  in  a  broad  deep  vessel,  sev- 
eral pounds  at  once,  (a  crucible  or  earthen  pot  will  answer,)  when 
its  surface  congeals,  break  it  and  pour  out  the  liquid  interior. 

(j.)  The  cavity  will  be  found  lined  with  prismatic  or  needle  form 
crystals,  of  which  the  basis  is  an  oblique  rhombic  prism. 

(k.)  With  water — no  action  ;  if  the  sulphur  be  pure,  it  comes  off 
tasteless  ;  but  precipitated  sulphur  is  a  hydrate,  and  is  white  ;  it  was 
formerly  called  lac  sulphuris. 

(I.)  With  liquid  alcohol — no  action  ;  in  vapor  they  unite,  a  vial 
of  alcohol  being  suspended  in  an  alembic  in  which  sulphur  is  sublim- 
ed, the  spirit  rises  too,  and  a  union  results ;  water  precipitates  the 
sulphur. 

(m.)  Boiling  essential  oil  of  turpentine  dissolves  sulphur  entirely, 
but  not  the  usual  impurities  ;  hence,  used  to  detect  its  adulterations  ; 
when  properly  purified,  it  has  a  fine  sparkling  brilliant  yellow  color.* 

4.  An  element  in  relation  to  our  knowledge. 

(a.)  Sir  H.  Davy  evolved  sulphuretted  hydrogen  from  it,  by  gal- 
vanism— but  is  not  certain  that  the  gas  did  not  come  from  decom- 
posed water,  lodged  in  the  interstices. f 

(b.)  Potassium  evolves  sulphuretted  hydrogen,  with  intense  heat 
and  light. 

7.  USES. 

(a.)  An  important  article  in  the  materia  medica,  both  internally, 
as  a  laxative,  and  externally,  as  a  remedy  against  cutaneous  dis- 
eases. 

b.)  The  basis  of  the  manufacture  of  sulphuric  acid, 
c.)  Used  with  iron  filings  as  a  cement,  and  for  matches. 
d.)  In  its  viscid  form  for  copying  medals,  &tc. 
e.)  The  chief  use  is  in  the  fabrication  of  gunpowder,  of  which  it 
visually  forms  15  per  cent.     For  these  and  other  purposes  it  is  large- 
ly imported  into  this   country  from    Italy,   whose  volcanic  regions 
abound  with  sulphur,  particularly  in  the  Solfaterra  near  Naples,  and 
it  comes,  in  perhaps  larger  quantities,  from  Sicily  than  from  Naples. 


*  Aikin's  Diet.  Vol.  II,  p.  353. 

i  Berzelius  found  that  when  metals  combine  with  sulphur,  as  dry  as  possible,  little 
or  no  sulphuretted  hydrogen  is  exhaled. 


INFLAMMABLES.  305 

(h.)  To  divide  a  bar  of  iron  ;  when  at  ignition,  or  better  at  a  white 
heat,  if  rubbed  with  a  roll  of  sulphur,  the  iron  melts  and  falls  in  drops 
of  liquid  sulphuret. 

"  If  a  gun  barrel  be  heated  red  hot  at  the  but-end,  and  a  piece  of 
sulphur  be  thrown  into  it,  on  closing  the  muzzle  with  a  cork,  or  blow- 
ing into  it,  a  jet  of  ignited  sulphurous  vapor  will  proceed  from  the 
touch  hole.  Exposed  to  this,  a  bunch  of  iron  wire  will  burn  as  if 
ignited  in  oxygen  gas,  and  will  fall  down  in  the  form  of  fused  glob- 
ules, in  the  state  of  proto-sulphuret.  Hydrate  of  potash,  exposed  to 
the  jet,  fuses  into  a  sulphuret  of  a  fine  red  color." — Dr.  Hare. 


5.  POLARITY — Electro  positive;  it  goes  to  the  negative  pole  in 
the  galvanic  circuit. 

6.  COMBINING  WEIGHT,  16,  hydrogen  being  1. 

8.  PHARMACY. — No  peculiar  preparation  is  necessary  to  fit  the 
best  roll  and  flowers  of  sulphur  for  medical  use.  Whether  it  is  acid 
may  be  learned  from  its  taste,  and  from  its  effects  on  the  test  colors ; 
if  it  turns  the  blue  vegetable  color  red,  it  must  be  washed  abund- 
antly with  hot  water,  and  the  addition  of  a  little  alkali  will  aid  in  re- 
moving the  acid. 

ACIDS. 

Preliminary  Remarks. 

One  of  these  bodies,  vinegar,  seems  to  have  been  always  known  to 
mankind.  In  the  progress  of  time  ;  accident,  art  and  science  have 
either  developed  or  formed  many  more.  There  can  be  no  doubt, 
that  the  acids  are  all  compound  bodies,  and  that  the  only  one  which 
remains  undecomposed,  the  fluoric,  has  an  inflammable  base,  like  the 
rest :  for,  with  this  exception,  all  of  the  hundred  or  more  that  are 

39 


306  INFLAMMABLES. 

known  to  chemistry,  have  inflammable  or  metallic  matter,  as  their 
basis,  and  with  only  a  few  exceptions,  it  has  been  proved  to  be  com- 
bined with  oxygen,  which,  instead  of  being  regarded  as  the  exclusive 
acidifying  principle,  may  still  be  viewed  as  sustaining  this  agency  in 
nearly  all  cases. 

Thirty  years  ago,  there  were  three  acids  whose  composition  was 
unknown,  namely,  the  muriatic,  the  boracic,  and  the  fluoric.  Although 
the  latter  is  still  undecomposed,  the  boracic  acid  has  followed  the 
general  analogy,  having  yielded  a  new  combustible  body,  boron,  united 
to  oxygen.  The  muriatic  acid  is  now  believed  to  be  composed  of  hy- 
drogen and  chlorine.  Sulphuretted  hydrogen  has  most  of  the  proper- 
tes  of  an  acid,  but  contains  only  sulphur  and  hydrogen  ;  the  hydriodic 
acid  consists  of  iodine  and  hydrogen,  and  the  prussic  acid  of  carbon  and 
nitrogen,  united  to  form  a  compound  base,  which  is  however  not  acid, 
until  it  unites  with  hydrogen.  Thus,  there  are  four*  acids  in  which 
hydrogen  appears  to  be  essential  to  the  acidity,  and  oxygen  is  not 
present ;  while  the  bases  of  three  of  these  acids,  namely,  sulphur,  io- 
dine, and  chlorine,  form  other  acids,  by  uniting  with  oxygen ;  and  even 
the  compound  basis  of  the  prussic  acid,  consists  of  elements  which, 
individually,  form  acids  with  oxygen. 

Some  chemists  are  now  inclining  to  the  opinion,  that  no  one  princi- 
ple can  be  regarded  as  being  endowed  with  the  peculiar  prerogative  of 
being  an  acidifier,  but  that  acidity  may,  and  often  does  arise  from  a 
balanced  or  conjoined  effect  of  several  principles. f  Oxygen  exists, 
as  we  have  seen,  in  all  the  alkalies,  except  ammonia,  and  in  all  the 
earths  and  metallic  oxides,  so  that  we  cannot  attribute  to  it  the  ex- 
clusive property  of  producing  either  acidity  or  alkalinity,  although  it 
is  in  most  instances  concerned  in  both  ;  still,  that  body  without  which 
another  would  not  be  acid,  must  be  considered  as  its  acidifier. 

Most  of  the  acids  that  have  been  discovered,  are  of  very  little  im- 
portance ;  but  several  of  the  principal  acids  are  eminently  valuable, 
and  their  history,  being  equally  instructive  and  interesting,  will  be 
developed  with  sufficient  detail,  in  connexion  with  that  of  the  in- 
flammable bodies  that  form  their  bases.  In  giving  the  history  of  the 
principal  acids,  I  shall  therefore  pursue  the  synthetical  course,  as 
being  the  most  convenient  and  intelligible,  although  the  analytical  was, 
for  the  same  reasons,  adopted  in  the  account  of  the  alkalies  and 
earths;  or,  in  other  words,  the  bases  of  the  most  important  acids  will 
be  presented  first,  whereas  those  of  the  fixed  alkalies  and  earths 
were  presented  last. 

*  Besides  others  of  a  most  doubtful  character,  as  that  composed  of  hydrogen  and 
tellurium. 

t  For  an  ingenious  discussion  of  this  view,  see  Murray's  Elements,  6th  Ed.  Vol. 
II,  Art.  Acids.  Mr.  Murray  is  inclined  to  think  that  even  the  water,  usually  re- 
garded as  combined  with  acids  and  alkalies,  acts  rather  by  its  element?,  than  in  the 
character  of  water,  a  fact  which  it  m;iy  be  difficult  either  to  prove  or  disprove. 


INFLAMMABLES.  307 

GENERAL    PROPERTIES    OF    ACIDS. THEIR    NOMENCLATURE. 

1 .  Most  of  them  sour. 

2.  Soluble  in  water  ;  most  of  them  largely — some  very  sparingly. 

3.  Redden  most  of  the  vegetable  blues — restore  the  colors  that 
have  been  changed  by  alkalies  or  alkaline  earths. 

4.  Combine  with  alkalies,  earths,  and  other  metallic  oxides,  and 
form  salts. 

5.  The  stronger  acids  corrosive. 

6.  They  consist  generally,  of  an  inflammable  base,  combined  with 
oxygen ;  in  a  few  cases  hydrogen  takes  its  place.* 

7.  Exist  solid,  fluid  and  gaseous,  in  different  cases. 

NOMENCLATURE    OF    THE    ACIDS. 

(a.)  In  the  new  or  French  nomenclature,  acids  are  named  from 
the  inflammable  bases. 

(b.)  The  termination  ic  denotes  the  higher  combination  with  oxy- 
gen ;  ows,  a  lower,  and  the  proportions  in  both  are  definite. 

(c.)  Where  there  is  only  one  proportion  of  oxygen  the  termination 
is  in  ic. 

(d.)  Where  the  base  is  complex,  as  in  the  animal  and  vegetable 
acids,  the  termination  ic  means  nothing,  and  the  acid  is  usually 
named  from  the  substance  which  affords  it ;  as  tartaric  acid,  from 
tartar,  &c. 

(e.)  The  names  of  the  hydracids,  as  they  are  called,  terminate  in 
1C,  as  hydrochloric,  hydriodic,  &c. 

SULPHURIC    ACID. 

1.  NAME. — Derived  from  sulphur,  the  inflammable  base,  which 
affords  also  other  acids.     Oil  of  Vitriol  is  the  name  of  the  shops.f 

2.  HISTORY. — Discovered  by  Basil  Valentine,  at  the  close  of  the 
15th  century. 

3.  EARLY  PROCESS. — By  distilling  sulphate^  of  iron,  (copperas,) 
whose  water  of  crystallization,  amounting  to  about  one  half  its  weight, 
had  been  previously  dissipated  by  a  moderate  heat.     This  process 
is  still  followed  in    Saxony ;  600  Ibs.  of  copperas  gave  Bernhardt 
but  64  of  the  acid,  and  when  no  water  was  put  into  the  receiver,  52 
pounds  of  a  dry  concrete  acid  were  obtained,  formerly  called  glacial 
oil  of  vitriol.     Glauber  says  that  sulphate  of  zinc  affords  a  purer  and 
better  acid,  and  with  less  heat.§ 


*  Sulphuretted  hydrogen  and  prussic  acid,  consist  wholly  of  combustible  elements. 
Chloric  acid  is  composed  of  two  supporters  of  combustion  and  some  would  refer  the 
oxiodic  and  the  chloriodie  acids  to  the  latter  class. 

t  Because  it  was  distilled  from  green  vitriol,  and  has  an  oily  consistence  ;  it  was 
called  spirit  of  vitriol,  when  it  was  less  concentrated. 

t  It  is  the  sulphate  of  the  protoxide,  which  passes  to  the  condition  of  peroxide. 

§  Parkcs'  Essays,  Vol.  I.  p.  468. 


308  INFLAMMABLES. 

4.  MODERN  PROCESS.* 

(a.)  Carried  on  in  chambers,  lined  throughout,  with  sheet  lead  ; 
usual  size,  20  feet  long,  and  12  wide — or  40  to  60  by  16  or  18; 
in  one  case,  in  England,  120  by  40,  and  20  high — contents  96000 
cubic  feet. 

(b.)  Sulphur,  7,  8  or  9  parts,  coarsely  bruised,  and  1  part  of 
common  nitre,  are  mixed. — One  pound  of  the  mixture  for  every  300 
cubic  feet  of  air,  is  placed  in  separate  portions  upon  iron  or  leaden 
plates,  supported  by  stands  of  lead.  The  sulphur  is  lighted  by  a  hot 
iron  and  the  door  closed,  f  The  combustion  continues  30  or  40 
minutes,  and  in  three  hours  the  acid  gas  is  absorbed  by  the  water  on 
the  floor  of  the  room,  which  is  usually  about  six  inches  deep ;  or 
sometimes  the  acid  vapors  are  carried  by  the  current  of  air  that  sup- 
ports the  combustion,  into  another  leaden  room,  where  they  are  con- 
densed by  water,  f 

(c.)  The  room  is  then  ventilated,  and  the  process  repeated  every 
four  hours,  day  and  night,  until  the  water  at  the  bottom  is  sufficiently 
acid. 

(d.)   Then  it  is  drawn  off  by  a  syphon,  into  a  leaden  reservoir. 

(e.)  It  is  pumped  from  this  into  leaden  boilers,  and  there  concen- 
trated||  by  heat,  until  it  is  of  the  sp.  gr.  1.350  to  1.450,  or  1.560. 

(f.)  It  is  finished  in  glass  retorts,  placed  in  sand  baths,  and  the 
retorts  are  now  generally  furnished  with  platinum  wire  to  prevent  the 
concussion  in  boiling  ;  water,  and  nitrous  and  sulphurous  acid  gas  be- 
ing expelled,  it  then  has  the  specific  gravity  1.850,  or,  as  Dr.  Ure 
says,  1.842,  if  pure.  For  economy,  the  concentration  of  sulphuric 
acid  is  now  often  performed  in  platinum  boilers,  placed  within  iron 
ones  of  the  same  size  and  form. 

The  conversion  of  sulphur  into  an  acid,§  is  easily  proved  by  burning 
it  in  a  pendent  metal  spoon,  introduced  into  a  bottle  of  oxygen  or 
common  air,  on  the  bottom  of  which  is  some  litmus  infusion.^ 

5.  PROPERTIES. 

(«.)  Thick,  oily  looking  fluid ;  pours  slowly  from  vessel  to  ves- 
sel ;  corrosive,  and,  with  or  without  heat,  destroys  all  animal  and 
vegetable  bodies ;  the  first  sensation  when  it  is  rubbed  on  the  skin, 
is  that  of  lubricity,  but  immediately  after,  there  is  extreme  burning. 

*  Begun  by  Dr.  Ward,  in  England,  before  1746,  by  combustion  in  glass  bells  or 
globes;  in  1746  Dr.  Roebuck  introduced  the  leaden  chambers  at  Birmingham. — 
Parkes'  Essays,  Vol.  I,  p.  476. 

t  A  red  hot  cannon  ball  is  sometimes  rolled  in  through  a  trough  lined  with  iron. 

t  The  theory  of  this  process  cannot  be  fully  elucidated  until  we  have  become  ac- 
quainted with  the  nitric  compounds,  when  it  will  be  resumed.  It  may  be  stated, 
however,  that  sulphurous  acid  is  formed  from  the  sulphur,  and  nitric  oxide  gas  from 
the  nitre ;  this  obtains  oxygen  from  the  air,  becomes  nitrous  acid  vapor,  then  oxy- 
genizes the  sulpburous  acid,  and  turns  it  into  sulphuric  acid. 

§  The  sulphurous. 

||  Concentration  is  when  a  volatile  ingredient  is  driven  off,  and  a  more  fixed  one  is 
Saved. — Distillation  when  the  volatile  ingredient  is  saved. 


INFLAMMABLES,  309 

(b.)  When  pure;  colorless,  limpid,  inodorous;  intensely  sour,  even 
when  largely  diluted  with  water. 

(c.)  Sp.  gr.  as  already  stated,  1.850, — or  (Ure,)  1.842  ;  ac- 
cording to  Dr.  Thomson,  1.847  ;  if  heavier,  it  may  contain  sulphate 
of  lead,  or  sulphate  of  potash,  or  both ;  2  J  per  cent,  of  sulphate  of 
potash  gives  it  the  sp.  gr.  of  1.860,  and  Dr.  Ure  states*  that  the  best 
acid  of  commerce  contains  from  J  to  f  of  1  part  in  100,  of  foreign 
matter,  which  is  sulphate  of  lead,  in  the  proportion  4,  to  sulphate  of 
potash  l.f 

(d.)  Its  purity  is  decided  by  saturating  it  by  an  alkali. — Dry  car- 
bonate of  soda,  100  grains,  neutralizes  92  grains  of  pure  liquid  sul- 
phuric acid,  and  100  of  the  acid  require  108,  or  108.5  of  the  car- 
bonate. J — Henry. 

(c.)  Produces  heat,  when  mingled  with  water  in  every  proportion  ; 
4  acid  -f  2  water =300°  Fahr. ;  or  better,  2§  acid  to  1  water,  or 
by  measure,  If,  or  1  £  acid  to  1  water.§ 

Place  a  thin  glass  tumbler  in  a  dish — pour  in  the  water — provide 
a  thin  glass  tube,  8  or  10  inches  long,  and  fill  it  two  thirds  with 
colored  water,  add  the  acid  in  a  slow  stream,  stirring  with  the  glass 
tube,  and  soon  after,  the  water  in  the  tube  will  boil,  and  another 
tube,  filled  with  alcohol,  will  also  be  made  to  boil. 

Explanation. — Increase  of  specific  gravity,  and  diminution  of  ca- 
pacity for  heat. 

Two  by  measure,  of  acid  -f-1  of  water,  starting  from  50° =300°, 
and  the  concentration  =^. 

(/.)  With  ice.— Ice  1-f-  acid  4=212°. 

ice  4-f-  acid  1  produce  intense  cold. 

In  both  instances,  the  affinity  of  the  acid  for  the  water  produces 
fusion,  as  the  two  cannot  unite  while  the  water  is  solid.  The  excess- 
of  acid  then  goes,  in  the  first  case,  to  produce  heat  with  the  water  form- 
ed ;  in  the  second  case,  there  being  no  more  acid  than  is  wanted  for 
the  fusion,  cold  is  produced,  upon  the  general  principle  that  fluidity 
requires  heat,  and  that  the  absorption  of  heat  produces  cold. 

(g.)  Absorption  of  water  from  the  air. — Rapid,  especially  if  ex- 
posed with  a  large  surface ;  in  one  day  3  parts  became  4,  and  1  oz. 
in  twelve,  months  gained  6^ ;  a  drachm  gained  in  five  successive  days, 
68,  58,  39,  23,  and  18  grains,  and  in  five  days  more  only,  5,  4,  3,  4  ; 
in  one  case,  in  fifty  six  days  a  drachm  became  6 J  drachms. 

*  Diet.  2d  Ed.  p.  91. 

t  The  acid  of  commerce  often  contains  3  or  4  per  cent,  of  salts,  and  sometimes 
more  arising  from  the  use  of  nitre,  to  remove  the  brown  color;  evaporation  in  a  pla- 
tinum dish  gives  a  prompt  result,  and  if  there  are  more  than  5  grains  in  500,  the  acid 
is  sophisticated. —  Ure. 

\  These  numbers  do  not  correspond  with  the  equivalents  of  sulphuric  acid  and 
carbonate  of  soda,  as  they  stand  in  our  modern  works.  100  acid  should  neutralize  very 
nearly  110  of  carbonate  soda.  (49  liq.  sul.  acid  :  54  carb.  soda : :  100  S.  A.:  110.2 
C.  S.)—  Communicated. 

§  Seventy  three  acid  to  twenty  seven  water,  or  very  nearly  3  acid  to  1  water.— Ure. 


310  INFLAMMABLES. 

(h.)  Discoloration  from  the  air,  fyc. — All  common  combustibles, 
even  the  floating  dust  in  a  room,  will  discolor  this  acid ;  a  drop  of 
oil  of  turpentine  does  it  instantly ;  it  is  decomposed  by  the  acid,  and 
carbon  developed. 

(i.)  The  pure  acid  is  not  rendered  turbid  by  dilution  with  water. — 
The  impurities  are  chiefly  sulphate  of  potash,  and  sulphate  of  lead ; 
the  latter  being  very  insoluble,  is  precipitated,  renders  the  acid  milky, 
and  in  time  subsides ;  hence  dilution  is  a  means,  to  a  certain  extent, 
of  purifying  the  acid.* 

(/.)  The  acid  is  purified  by  distillation. — Dr.  lire's  method  is 
good,  and  avoids  the  danger  which  was  encountered  in  the  old  way. 

Arrangement. — A  retort  of  from  2  to  4  quarts  capacity ;  acid  1 
pint,  adopter  3  or  4  feet  long,  terminating  in  a  large  receiver  ;  apply 
a  charcoal  fire  to  the  naked  retort,  which  should  contain  along  with 
the  acid,  a  few  pieces  of  broken  glass,  or  some  platinum  wire,f  or 
platinum  foil,  which  will  prevent  the  heavy  recoil  upon  the  glass, 
produced  by  the  sudden  condensation  of  vapor,  and^  by  the  great 
weight  of  the  fluid. 

(k.)  Boiling  point. — Acid  of  sp.  gr.  1.850  containing  81  per  cent, 
real  acid,  boils  at  620°,  and  at  a  lower  temperature,  in  proportion  as 
it  is  mingled  with  more  water;  that  of  sp.  gr.  1.849,  boils  at  605°, 
and  contains  80  per  cent  real  acid  ;  that  of  sp.  gr.  1.838  containing 
real  acid  75  per  cent,  boils  at  530°,  &c.  It  is  rendered  stronger 
by  heating,  until  the  acid  itself  rises  in  vapor,  and  if  mingled  with 
combustible  matter,  this  is  burned  off  by  heating  it. 

(Z.)  The  freezing  point. — This  depends  on  the  dilution  of  the 
acid.  If  of  sp.  gr.  1780,{  it  congeals  at  45°  ;  viz.  with  13  degrees 
less  than  causes  water  to  freeze  ;  it  freezes  at  32°,  if  any  where  be- 
tween 1.786,  and  1.775;  if  1.843,  or  like  that  of  commerce,  it 
freezes  at— 15°  ;  and  if  half  water,  at  — 36°. 

When  once  frozen,  it  does  not  easily  melt ;  it  sometimes  forms 
regular  prismatic  crystals. § 

(m.)  Effects  on  the  test  fluids,  the  same  that  were  mentioned  under 
the  general  properties  of  acids ;  infusion  of  litmus  is  very  sensible, 
and  that  of  purple  cabbage  sufficiently  so ;  alkanet  tincture,  previ- 
ously blued  by  a  little  ammonia,  is  instantly  turned  red  again  by  a 
drop  of  the  diluted  acid. 

*  Dr.  Ure,  by  evaporating  100  parts  of  sulphuric  acid,  in  a  platinum  dish,  obtained 
three  quarters  of  a  part  of  solid  matter,  of  which  2  (*4  ?  p.  309,  c.)  was  sulphate  of 
potash,  andl  sulphate  of  lead. — Jour.  Science,  Vol.  IV,  p.  115. 

For  a  table  of  the  boiling  point  of  acid  of  different  densities,  see  Henry,  Vol.  I, 
p.  386,  and  Eng.  Jour.  Science,  VoL  IV,  p.  127. 

t  I  have  found  it  to  succeed  well  without  this  precaution,  which,  however,  it 
might  be  advisable  to  take. 

t  Easily  brought  to  this  specific  gravity  by  mingling  6  1-8  parts  of  the  acid  of 
commerce  with  1  1-8  of  water. — Thomson's  First  Principles,  Vol.  I,  p.  214. 

§  See  Am.  Jour.  Vol.  VI,  p.  186. 


INFLAMMABLES.  311 

6.  DECOMPOSITION. 

(a.)  Driven  in  vapor  through  a  red  hot  platinum  tube,  or  a  small 
tube  of  glass  or  porcelain,  this  acid  is  decomposed,  and  affords  sul- 
phurous acid  gas,  two  volumes,  and  oxygen  gas  one  volume. 

(b.)  Its  decomposition  is  best  effected  upon  one  of  its  salts,  as  will 
be  mentioned  under  sulphate  of  baryta,  from  which  we  can  obtain  the 
sulphur. 

(c.)  Heated  with  charcoal  powder,  it  is  decomposed,  and  various 
gases  are  evolved,  as  will  be  mentioned  farther  on. 

(d.)  When  it  chars  any  animal  or  vegetable  substance,  it  suffers 
decomposition. 

Se.)  Decomposed  by  galvanism — sulphur  appears  at  the  negative, 
oxygen  at  the  positive  pole,  platinum  wires  being  used. 
(/.)  By  being  passed  through  an  ignited  porcelain  tube  along  with 
hydrogen,  which  unites  with  its  oxygen  and  precipitates  the  sulphur, 
and  perhaps  evolves  sulphurous  acid  gas. 

7.  PROPORTION  OF  ITS  CONSTITUENTS  AND  COMBINING  WEIGHT. 
(a.)   Centesimal  ratio. — Writers  vary  between  43.28  sulphur,  and 

56.72  oxygen,  and  40  sulphur  and  60  oxygen.  Dr.  Wollaston  ad- 
mits the  latter  numbers,  and  Berzelius  those  that  approximate  to 
them  ;  40  and  60  are  probably  correct. — Murray. 

(b.)  Equivalent  numbers. — The  proportions  of  40  and  60,  corres- 
pond with  1 6  of  sulphur,  1  proportion,  and  24  of  oxygen,  3  propor- 
tions, making  40  for  the  representative  number  of  the  dry  acid,  and 
liquid  sulphuric  acid  =  1  real  acid,  40,  and  1  of  water  9— 49. 

It  is  supposed  that  by  volume,  the  sulphur  would  be  represented 
by  100,  and  the  oxygen  gas  by  150,  for  oxygen  gas  is  considered  as 
combining  in  the  proportion  of  half  a  volume  which  would  be  50,  if 
the  1  proportion  of  sulphur  is  called  100,  and  there  are  3  of  oxygen, 
which  would  of  course  be  150. 

8.  ANHYDROUS  ACID. 

(a.)  The  dark  fuming  acid,  already  mentioned  as  being  obtained 
by  distilling  green  vitriol,  has  a  sp.  gr.  of  1.896  or  1.90,  and  boils 
from  102°  to  122°  Fahr. 

(b.)  Heated  in  a  glass  retort  to  which  a  receiver  is  attached,  sur- 
rounded by  snow  and  salt,  half  of  the  acid  passes  over  in  a  state  re- 
sembling asbestos,  and  is  regarded  as  sulphuric  acid  without  water, 
or  the  anhydrous  acid,  and  the  acid  remaining  in  the  retort  is  like 
the  common  oil  of  vitriol,  composed  of  acid  one  proportion,  and  water 
one. 

(c.)  It  is  the  pure  acid  without  water. 

(d.)  It  smokes  violently  when  exposed  to  the  air,  and  is  dissipated 
too  speedily  to  admit  of  being  weighed.  It  is  less  corrosive  than 
common  sulphuric  acid.  It  crystallizes  in  tough  silky  filaments  like 


312  INFLAMMABLES. 

asbestos,  or  in  flat  transparent  rhomboids,  of  which  the  large  angles 
are  but  little  above  90°. 

Thrown  into  water,  it  acts  like  red  hot  iron. 

It  liquifies  at  66°,  is  more  fluid  than  the  common  acid,  and  has  a 
specific  gravity  of  1.97. 

9.  IMPORTANCE  AND  USES  OF  SULPHURIC  ACID. 

(a.)  Largely  used  in  chemistry,  being  the  most  common  agent  in 
decompositions,  where  other  acids  are  to  be  separated  from  their  com- 
binations. 

(6.)  For  generating  hydrogen,  with  the  aid  of  zinc  or  iron,  and 
water,  for  filling  balloons. 

(c»)  For  the  manufacture  of  soda  water,  to  evolve  the  gas  from 
marble  powder. 

(d.)  For  manufacturing  nitric,  muriatic,  citric  and  tartaric  acids. 

(«»)  In  dyeing,  bleaching,  cleaning  metals  from  oxide,  and  hVpre- 
paring  chlorine  for  disinfection. 

(jf.)  In  forming  metallic  sulphates,  as  those  of  copper,  zinc,  and 
iron ;  in  making  calomel,  and  corrosive  sublimate,  and  sulphuric  ether ; 
in  dissolving  indigo,  extracting  phosphorus,  &c. 

(g.)  In  medicine,  largely  diluted — 50  or  60  parts  of  water  to  1  of 
acid.*  Used  as  an  antifebrile  drink,  and  as  a  tonic  and  stimulant.  It  is 
also  used  externally  as  a  caustic,  and  in  the  composition  of  elixir  vi- 
triol, &c.  Externally,  as  a  gargle  in  putrid  sore  throats,  and  apthous 
mouths,  and  as  a  wash  in  cutaneous  diseases.  In  its  concentrated 
state,  it  is  a  violent  poison,  and  the  person  who  swallows  much  of  it, 
dies  in  agony ;  chalk  and  carbonate  of  magnesia,  are  the  best  rem- 
edies. 

10.  DIFFUSION  IN  NATURE. 

Largely  in  combination,  as  in  the  earthy  and  metallic  sulphates,  but 
not  much  known  in  a  free  state  5  occurs  in  that  condition  in  the  cra- 
ter of  a  volcano  at  Mount  Idienne,  in  Java,  &c. ;  also,  observed  by 
Baron  Humboldt,  in  the  river  Vinagre,  in  the  Andes  of  Popayan.f 

Found  in  the  cavities  of  a  small  volcanic  hill,  called  Zoccolino,  near 
Sienna  ;  also,  in  the  state  of  New  York.f 

11.  TEST. — Muriate  of  barytes ;  it  acts  by  giving  its  earth  to 
this  acid,  and  by  thus  taking  it  from  every  combination,  it  affords  us 
an  infallible  test  for  the  sulphuric  acid ;  the  precipitate  is  a  heavy 
white  powder. 

12.  POLARITY. — Electro-negative ;  it  is  attracted  to  the  positive 
pole  in  the  galvanic  series. 


*  Or,  as  much  as  will  make  it  agreeable,  and  it  may  be  qualified  with  sugar.  To 
prevent  its  injuring  the  teeth,  it  is  usual  to  suck  it  through  a  quill,  but  a  glass  tube 
would  be  better. 

I  Boston  Jour.  Vol.  II,  p.  460.        J  By  Prot.  Eaton— Am.  Jour.  Vol.  XV,  p.  23. 


INFLAMMABLES.  313 

Remark. — According  to  Berzelius,  a  minute  quantity  of  titanium 
exists  in  the  English  acid,  and  of  tellurium  in  that  of  Sweden. 

SULPHUROUS  ACID. 

1.  HISTORY. 

This  gas  being  produced  whenever  sulphur  is  burned,  it  has  proba- 
bly always  been  known,  although  it  was  not  recognized  as  a  distinct 
chemical  agent,  until  noticed  by  Stahl ;  but  it  was  first  obtained  pure 
by  Dr.  Priestley.* 

2.  PREPARATION. 

(a.)  In  a  glass  globe  or  bottle,  burn  sulphur  in  common  air,  either 
in  a  pendent  spoon, f  or  by  means  of  a  sulphur  match ;  sulphurous 
acid  gas  will  be  formed,  and  if  there  be  litmus  or  cabbage  infusion 
in  the  bottle,  it  will  be  reddened,  and  eventually  the  color  will  be  des- 
troyed, 

(b.)  The  same  result  is  obtained  with  oxygen  gas  ;  the  combus- 
tion is  brilliant,  with  a  blue  and  white  light,  and  the  product  is  entire- 
ly sulphurous  acid.  There  is  no  change  in  the  volume  of  oxygen 
gas,  but  the  weight  is  doubled. 

One  volume  of  sulphur  vapor  unites  with  one  volume  of  oxygen. 

(c.)  Red  oxide  of  mercury  and  sulphur,  equal  parts,  or  sulphur 
12,  and  peroxide  of  manganese,  100  parts,  mingled  in  powder 
and  heated,  produce  sulphurous  acid  gas;  in  the  former  case,  one 
cubic  inch  is  obtained  for  every  5  grains  of  the  oxide  ;  the  latter  pro- 
cess is  recommended  as  being  a  very  good  one. 

(d.)  The  best  process  is,  by  mercury  1  part,  with  6  or  7J  of  sul- 
phuric acid,  in  a  small  glass  retort ;  apply  the  heat  of  a  lamp  or  of  a 
few  coals,  and  obtain  the  gas  over  mercury,  or  by  a  recurved  tube 
passing  to  the  bottom  of  a  jar  or  bottle,  and  displacing  the  common 
air,  as  exhibited  in  the  figure  on  p.  232,  only  substituting  an  empty 
bottle  for  the  bottle  of  water — theory,  the  mercury  detaches  1  pro- 
portion of  oxygen,  and  leaves  the  whole  of  the  sulphur  combined  with 
the  remaining  two  proportions  of  oxygen,  and  thus  evolves  the  sulphu- 
rous acid  gas  ;  the  sulphate  of  mercury  which  is  formed,  may  be  sav- 
ed for  future  use. 

(e.)  Sulphuric  acid  is  decomposed  by  many  other  things  ;  it  may 
be  boiled  on  charcoal,  wood,  straw,  cork  or  almost  any  vegetable 


*  On  Air,  Vol.  II,  p.  1. 

t  Pendent  spoons  are  easily  made  by  cutting  a  slip  of  sheet  copper,  into  the  form 
of  a  very  acute  isosceles  triangle,  the  sharp  end  may  be  tlmist  through  a  cork,  and 
the  other  be  hammered  into  a  spoon  and  turned  at  right  angles. 

I  Metal  2.  acid  3.  (Turner,)  with  so  small  a  proportion  of  acid,  there  might  be 
danger  of  breaking  the  retort;  it  is  better  to  use  an  excess  of  acid  which  can  be  af- 
terwards poured  off.  Thenard  directs  6  or  7  of  acid  to  1  of  mercury. 

40 


314  INFLAMMABLES. 

substance,  and  sulphurous  acid  gas  will  be  obtained ;  but  there  are 
other  gases  produced,  and  the  process  is  much  less  neat  than  when 
mercury  or  copper  is  employed  ;  tin  answers  equally  well. 

3.  COMPOSITION  AND  PROPERTIES. 

(a.)  Sulphurous  acid  gas  is  composed  of  1  volume  of  sulphur  in 
vapor,  and  1  volume  of  oxygen  condensed  into  one  volume, f  or  we 
may  say  that  the  volume  of  the  oxygen  gas  is  not  changed,  but  an 
equal  weight  of  sulphur  is  added  to  it. 

Its  sp.gr.  being  2.22,*  and  that  of  oxygen  gas  1.11,  therefore 
the  weight  of  the  gas  is  divided  equally  between  the  oxygen,  and  the 
sulphur. 

(6.)  100  cubic  inches  weigh  nearly  68  grains  ;  accurately,  it  should 
be  67.776  grains,  containing  33.888  of  sulphur,  that  is,  just  half.f 

(c.)  It  is  fatal  to  life,  producing  spasms  of  the  glottis,  and  killing 
both  by  suffocation  and  excoriation  ;  used  to  destroy  bees.§  Intol- 
erably suffocating,  disgusting,  and  distressing,  even  when  breathed  in 
moderate  quantity,  and  mixed  with  much  air ;  it  creates  a  cough 
and  a  stricture  of  the  breast. 

(d.)  Extinguishes  combustion  ;  best  shewn  by  a  pendent  candle 
let  down  into  a  jar  of  the  gas,  as  exhibited  in  a  note  to  p.  187 ;  it 
may  be  extinguished  many  times,  and  then  the  gas  may  be  poured 
upon  other  candles,  and  will  run  down  like  water  and  extinguish 
them. 

(e.)  Fugaciously  reddens,  and  soon  bleaches  the  dark  vegetable  col- 
ors.— A  red  rose  becomes  white  in  it,  as  may  be  beautifully  shown 
by  holding  a  red  rose  over  a  burning  sulphur  match,  when  it  will  be- 
come first  variegated  and  then  white,  and  immersion  in  water  re- 
stores the  color  ;  litmus  paper  is  first  reddened  and  then  becomes 
white.  The  color  is  not  decomposed,  for  it  can  be  restored  by  a 
stronger  acid  or  by  an  alkali. —  Turner. 

^  (f.)  The  aqueous  solution  is  prepared  by  passing  the  gas,  with  a 
recurved  tube,  through  water,  which,  when  kept  cold  by  snow,  ab- 
sorbs 33  times  its  volume  ;||  or  100  grains  absorb  8.2  of  the  gas. 

(g.)  The  gas  is  spontaneously  disengaged  into  the  air  ;  rapidly  by 
sulphuric  acid. 

(A.)  Sulphuric  acid,  saturated  ivith  the  sulphurous,  crystallizes 
with  a  moderate  reduction  of  heat ;  when  distilled,  it  crystallizes 
and  becomes  solid. 

(i.)  Not  decomposed  by  heat. 


*  2.234,  Thenard— 2.25,  Th.  and  G.-Lus.  t  Thomson's  First  Priu.  I.  216. 

t  Ann.de  Chim.  et  de  Phys.  Vol.  V. 

§  A  gratuitous  cruelty,  as  they  can  be  transferred  to  another  hive,  and  thus,  both 
the  bees  and  the  honey  can  be  saved.  |j  At  61°. —  I'ic. 


INFLAMMABLES.  315 

.00  If  two  measures  of  sulphurous  acid  gas  and  one  of  oxygen  be 
mingled  in  a  jar,  standing  over  mercury,  and  a  little  water  be  added, 
sulphuric  acid  will  be  formed  ;  the  same  result  is  obtained  by  passing 
the  mixed  gases  through  a  red  hot  tube,  or  causing  the  electric  spark 
to  pass  through  them. 

(k.)  Becomes  liquid  by  great  cold  ;  or  by  moderate  cold,  — 31°, 
if  aided  by  pressure. 

(/.)  Decomposed  when  passed  over  ignited  charcoal,  or  with  hy- 
drogen, through  a  red  hot  tube  ;  water  and  sulphur  are  the  products 

(m.)  Liquid  sulphurous  acid  does  not  give  up  its  gas  by  freezing, 
and  becomes  so  heavy  as  to  sink  in  water. 

(n.)  Boiling  expels  the  gas,  although  the  water  remains  acid,  from 
the  formation  of  sulphuric  acid. 

(o.)  Exposed  to  the  air,  the  liquid  acid  becomes  slowly  sulphuric 
acid,  absorbing  oxygen  gas  from  the  air ;  its  smell  is  like  that  of  the  gas. 

(p.)  Decomposed,  by  potassium*  heated  in  it ;  products,  probably 
potassa  and  sulphuret  of  potassium ;  also,  at  ignition,  by  hydrogen, 
forming  water  and  leaving  sulphur ;  and  by  carbon,  producing  carbo- 
nic acid  and  carbonic  oxide,  and  liberating  sulphur. 

(q.)  Sulphurous  acid  attracts  oxygen  powerfully ;  it  converts  the 
peroxide  into  the  protoxide  of  iron  ;  the  same  with  manganese,  and  it 
precipitates  gold,  platinum,  and  mercury  in  the  metallic  state,  be- 
cause their  affinity  for  oxygen  is  feeble  ;  it  becomes  itself,  in  the 
mean  time,  sulphuric  acid,  by  acquiring  one  proportion  of  oxygen. 

(r.)  Condensation  of  sulphurous  acid  gas. — Mr.  Faraday,f  by 
confining,  in  a  bent  glass  tube,  both  sulphuric  acid  and  mercury,  and 
applying  heat,  caused  the  sulphurous  acid  gas  which  they  produced 
by  their  reaction,  to  pass  into  the  other  end  of  the  tube,  cooled  by  a 
freezing  mixture,  and  thus  obtained  the  sulphurous  acid  in  a  liquid 
state.  The  pressure  was  about  two  atmospheres. 

(s.)  Mr.  Bussy\  also  obtained  the  liquid  anhydrous  acid,  from 
the  above  named  materials,  by  passing  the  dried  gas  into  a  vessel 
cooled  by  ice  or  snow,  then  through  a  tube  containing  melted  muri- 
ate of.lime,  and  finally  into  a  matrass  surrounded  by  a  mixture  of 
ice  2  parts  and  common  salt  1  ;  in  this,  the  gas  is  condensed  into  a 
liquid,  at  the  common  atmospheric  pressure.^ 

*  It  is  decomposed  in  the  same  manner  by  sodium. 

t  Phil.  Trans.  1823,  p.  190. 

i  Ann.  Phil.  Vol.  VIII,  p.  307,  N.  S. 

&  M.  A.  de  la  Rive  (Bib.  Univ.  Mars,  1829,  and  Am.  Jour.  Vol.  XVII,  p.  166,) 
directs  that  a  second  tube,  filled  with  muriate  of  lime,  should  pass  from  the  second 
to  a  third  vessel  cooled  like  the  others,  and  from  this  a  tube  may  proceed  to  the  mer- 
curial cistern.  The  junctures  must  be  luted  tight.  The  gas  having  been  disenga- 
ged during  8  or  10  hours,  white  crystals,  (hydrates)  are  found  in  the  vessel  No.  1 ; 
they  resemble  the  hydrate  of  chlorine ;  they  are  said  to  remain  solid  at  4°  or  5°  (centi- 
grade •)  and  in  Nos.  2  and  3,  is  the  liquid  sulphurous  acid,  which  must  be  immediately 


316  INFLAMMABLES. 

(t.)  Sir  H.  Davy,  substituting  the  pressure  of  the  vapor  of  ether  for 
that  of  the  gas  itself,  and  causing  the  former,  through  the  medium  of 
mercury  in  the  bend  of  the  tube,  to  press  upon  the  latter  in  the  other 
leg,  while  cold  was  applied,  succeeded  in  condensing  the  sulphurous 
acid  into  a  fluid.* 

4.  PROPERTIES  OF  THE  LIQJJIFIED  GAS. 

(a.)  Limpid,  colorless,  refractive  power  similar  to  that  of  water  ; 
when  the  tube  was  opened  it  evaporated  rapidly,  but  without  explo- 
sion. 

(b.)  Sp.  gr.  1.45 — bolls  at  14°  Fahr.  and  evaporates  rapidly,  but 
without  explosion,  cooling  the  residuary  fluid  to  0,  so  that  it  re- 
mains some  time  liquid  under  the  pressure  of  the  atmosphere. 

(c.)  JY0  visible  fumes,  but  a  strong  smell  of  sulphurous  acid, 
eventually  leaving  the  tube  dry. 

(d.)  Ice  dropped  into  the  fluid,  proved  so  much  warmer,  that  the 
ice  made  the  fluid  boil. 

(e.)  Mercury  is  frozen  by  the  cold  produced  by  the  evaporation 
of  sulphurous  acid  ;  for  this  purpose  the  ball  of  a  thermometer  tube 
is  surrounded  with  cotton,  and  kept  wet  with  the  liquid. 

(jf.)  By  its  aid,  and  that  of  a  moderate  pressure,  several  addition- 
al gases  have  been  liquified. f  The  cold  was  carried  to  —60°,  but 
absolute  alcohol  and  ether  did  not  freeze.  One  part  of  the  acid 
in  a  watch  glass,  freezes,  by  the  spontaneous  evaporation  of  the 
other. 

5.  COMBINING  WEIGHT. 

Sulphurous  acid  consists  of  1  proportion  of  sulphur  16, -f-2  of  oxy- 
gen 16  =  32,  which  is  therefore  its  equivalent  number. 

6.  POLARITY. — Like  other  acids,  it  is  electro  negative,   as  it  is 
attracted  to  the  positive  pole  in  the  galvanic  arrangement. 

7.  SULPHUROUS  ACID   IN   VOLCANOS    AND  SOLFATERRAS. — It  is 
constantly  emitted  wherever  volcanic  fires  are  active.     This  arises 
from  the  combustion  of  sulphur,  raised  by  the  subterranean  heatr 
and  burned  by  the  air  in  its  passage.     Those  who  visit  volcanic  cra- 
ters and  solfaterras  are  constantly  incommoded  by  this  gas,  and  ^often 
find  it  necessary  to  mount  some  elevation  in  order  to  escape  from 
suffocation. 


corked  tight,  and  the  vessel  must  be  constantly  surrounded  by  a  freezing-  mixture, 
else  the  gas  will  escape,  or  the  vessel  explode.  A  few  drops  of  the  liquid  sulphu- 
rous acid  thrown  upon  water,  produces  a  crust  of  ice. 

If  mercury,  of  the  volume  of  a  hazlenut,  is  moistened  by  a  few  drops  of  the  acid, 
and  the  apparatus  placed  under  an  exhausted  receiver,  the  metal  will  freeze  solid, 
and  a  considerable  mass  may  be  thus  frozen  and  preserved  for  a  few  minutes.  It  is 
found  that  solid  mercury  is  a  much  better  conductor  of  electricity  than  the  fluid 
metal.  In  its  pure  liquid  state,  it  was  not  decomposed  by  electricity,  but  if  a  little 
water  was  added,  sulphuretted  hydrogen  appeared  at  one  pole,  and  oxygen  at  the 
other. 

*  See  Faraday's  Chemical  Manip.  p.  205.       t  Ann.  Phil.  N.  S.  Vol.  VIII,  p.  307, 


INFLAMMABLES.  317 

8.  USES,  INT  BLEACHING,  and  for  other  purposes* 

Jz.)  It  bleaches  straw,  woolen  and  silky  and  gives  silk  lustre* 
ulphur  is  burned  in  a  barrel,  in  family  operations ;  the  articles 
to  be  bleached  are  hung  up  in  the  barrel,  and  moistened  with  water  or 
solution  of  pearlashes.f  It  also  discharges  iron  moulds  and  vegeta- 
ble stains  from  linen.  For  this  purpose,  the  places  must  be  made 
thoroughly  damp,  and  then  two  or  three  sulphur  matches  must  be 
burned  close  to  them ;  liquid  sulphurous  acid  will  thus  be  formed, 
and  the  spots  will  soon  disappear. 

(b.)  A  similar  process  is  practised  on  a  large  scale  in  the  arts  ; 
the  sulphur  is  burned  in  chambers  lined  with  sheet  lead,  and  the 
moistened  articles  are  hung  upon  frames.  J 

(c.)  Prepared  of  a  proper  strength  for  liquid  bleaching,  by  dis- 
tilling in  a  glass  retort  1  Ib.  of  wood  shavings,  with  the  same  weight 
of  sulphuric  acid,  and  placing  two  gallons  of  water  in  the  receiver ; 
if  to  be  used  to  stop  the  fermentation  of  wine,  only  two  quarts  of 
water  are  placed  in  the  receiver. 

(d.)  A  rag,  imbued  with  sulphur,  is  sometimes  burned  in  cider 
casks  to  preserve  the  cider  from  too  rapid  fermentation. 

(e.)  The  fumes  of  burning  sulphur,  (or  in  other  words,  sulphurous 
acid  gas,)  were  employed  1600  years  ago  in  bleaching  wool;  but 
the  gas  whitens  only  the  surface,  and  therefore  the  liquid  acid  is  pre- 
ferred. 

(/.)  Thenard  says§  that  the  sulphurous  acid  is  beginning  to  be 
used  to  cure  diseases  of  the  skin — that  there  are  in  various  hospit- 
als in  Paris,  baths  of  this  kind — that  a  few  applications  suffice  to 
remove  psora,  and  that  the  tetters  yield  to  the  continued  use  of 
this  remedy.  It  is  said  that  Dr.  Gules,  of  Paris  appliesj|  the  vapor 
of  burning  sulphur  mixed  with  air,  to  the  surface  of  the  body,  as  an 
air  bath,  with  much  advantage  in  many  chronic  diseases  of  the  joints, 
the  glands,  and  the  lymphatics. — Ure. 

******* 

Dr.  Torrey  informs  me  that  he  has  made  the  liquid  sulphurous 
acid  before  his  class,  and  that  tubes  of  it  may  be  sealed  by  the  blow- 
pipe, while  immersed,  (except  the  capillary  extremity,)  in  a  freezing 
mixture. 

The  hypo-  or  sub-sulphurous,  and  the  hypo-  or  sub-sulphuric  acids 
will  be  mentioned  after  the  sulphates  and  sulphites* 


*  Sec  Parkes  on  Bleaching.    Essays,  Vol.  II,  p.  337. 

t  Water  would  probably  be  better,  as  the  alkali  would  neutralize  a  part  of  the- 
acid  gas,  and  withdraw  it  from  action. 

I  Verbal  communication  to  the  author  while  in  England,  from  a  manufacturer. 

§  Fifth  Ed.  VII,  p.  195. 

fl  In  an  apparatus  called  Boite  Fumigatoire. 


318  SALTS. 

SALTS. 

Introductory  Remarks. 

That  the  student  may  not  be  fatigued  by  a  too  frequent  reiteration 
of  similar  properties,  the  history  of  saline  bodies  will  be  given,  in  di- 
visions, under  that  of  the  acids,  which  they  respectively  contain,  in  the 
same  manner  as  that  of  the  principal  acids  is  given,  under  combustibles. 

We  shall  thus  dispose  of  the  salts  in  convenient  groups,  and  the 
most  important  will  be  brought  into  view,  as  early  as  possible. 

As  many  of  the  salts  are  unimportant,  the  history  of  some  of  them 
will  be  abridged,  and  that  of  others  omitted,  or  included  in  a  general 
statement  of  the  properties  of  the  genus  to  which  they  belong.  Some 
of  the  salts  are,  however,  eminently  important  and  interesting,  and 
therefore  the  history  of  such  salts  will  be  developed,  with  all  the  ne- 
cessary details.  Under  the  head  of  attraction  and  crystallization, 
many  things  have  been  stated  respecting  saline  bodies,  which  need 
not  be  repeated  here,  and  various  generalizations  will  be  prefixed  to 
the  first  genus.  It  remains,  to  make  a  few  other  observations,  by 
way  of  introduction  to  the  history  of  saline  bodies  generally. 

As  salts  consist  of  acids  and  salifiable  bases  ;  alkalies,  earths,  and 
metallic  oxides,  we  observe  that  the  powers  of  saturation  differ  very 
widely  among  these  agents ;  it  takes  much  more  of  some  bases  to  satur- 
ate a  given  acid  than  of  others,  and  vice  versa,  of  different  acids  to 
saturate  a  given  base.  This  evidently  depends  upon  the  number  ex- 
pressing the  combining  powers  of  those  different  bodies ;  or  rather 
the  formation  of  salts  is  only  a  mode  of  ascertaining  and  expressing 
this  very  fact,  in  relation  to  acids  and  bases.  For  instance,  the  com- 
bining power  of  nitric  acid  is  expressed  by  54,  that  of  lime  by  28, 
and  that  of  baryta  by  78 ;  to  form  then  anhydrous  nitrate  of  lime, 
54  parts  of  nitric  acid  will  unite  with  28  of  lime,  and  the  chemical 
equivalent  of  nitrate  of  lime  will  be  54+28=82;  but  to  saturate  54 
of  nitric  acid,  requires  78  of  baryta,  and  therefore  the  chemical 
equivalent  of  nitrate  of  baryta  will  be  54+78  =  132. 

Now,  suppose  lime  and  baryta  to  be  combined,  each  with  two 
acids ;  say  the  nitric  and  the  sulphuric ;  the  numbers  expressing  the 
combining  powers  of  these  earths  being  as  above  stated,  and  that  of 
sulphuric  acid  being  40,  the  sulphate  of  baryta  will  be  expressed  by 
40+78=118,  and  that  of  the  sulphate  of  lime  by  40+28  =  68,  the 
salts  being  supposed  anhydrous.  It  was  suggested  by  Berthollet,  and 
the  idea  was  adopted,  more  or  less,  by  many  chemists,  that  the 
strength  of  affinity  is  inversely  as  the  saturating  power  ;  but  this  idea 
is  inconsistent  with  facts  ;  e.  g.  40  parts  of  sulphuric  acid  require  28 
of  lime  and  78  of  baryta  for  saturation,  and  therefore  baryta  should 
attract  sulphuric  acid  less  powerfully  than  lime,  which  is  not  true. 


SALTS. 

Triple  Salts  are  those  which  have  two  bases  united  to  one  acid, 
as  the  phosphate  of  soda  and  ammonia ;  this  may  be  regarded  as  two 
phosphates  combined,  or  as  a  phosphate  of  two  bases ;  some  prefer 
to  call  such  combinations  double  salts. 

Neutral  Salts  were  formerly  regarded  as  those  in  which  the  pro- 
perties of  the  acid  and  base  are  both  entirely  lost,  as  in  sulphate  of 
potassa  ;  but  sometimes  there  are  peculiar  characters  imparted  by 
the  acid  or  base,  more  commonly  by  the  latter ;  e.  g.  the  salts  of  am- 
monia are  volatile ;  of  magnesia  bitter ;  of  alumina  styptic ;  and  of 
glucina  sweet.  The  nitrates  are  cooling,  and  they  deflagrate  with  red 
hot  charcoal.  In  general,  a  salt  is  said  to  be  insoluble,  if  it  requires 
1000  parts  of  water  for  its  solution. 

Salts  are  not  only  compound  bodies,  but  the  acids  and  bases  of 
which  they  consist,  are  also  compound.  Thus,  in  sulphate  of  soda, 
the  acid  is  composed  of  oxygen  and  sulphur,  and  the  base  of  oxygen 
and  sodium.  It  has  been  imagined  by  some,  that  in  salts,  the  ele- 
ments, losing  the  form  of  acids  and  bases,  are  directly  united  to 
each  other,  so  as  to  produce  ternary  or  quaternary  compounds. 
Thus,  in  sulphate  of  soda,  the  oxygen,  which  exists  in  the  acid,  in 
the  base,  and  in  the  water  of  crystallization  ;  the  sulphur  of  the  acid ; 
the  sodium  of  the  base,  and  the  hydrogen  of  the  water,  are  regarded 
as  being  in  immediate  union,  to  form  a  quaternary  compound; 
but  of  the  truth  of  this  speculation  there  is  no  direct  proof;  and 
it  is  extremely  improbable  that  it  is  true,  because  the  acid,  the  base 
and  the  water  can  be  combined  synthetically,  to  form  the  salt ; 
the  water  can  be  expelled  by  heat  and  recovered,  and  the  galvanic 
power  will  separate  the  acid  and  alkali  unaltered,  in  full  proportion, 
and  we  know  not  of  any  affinity  which  should  unite^these  bodies  in 
a  quaternary  combination,  and  then  resolve  them  again  into  binary 
compounds. 

NOMENCLATURE  AND  CHARACTER  OF  SALTS. 

1.  As  almost  every  acid  unites  with  nearly  every  base,  and  some- 
times in  more  than  one  proportion,  it  follows  that  the  salts  are  very 
numerous. 

2.  They  are  said  to  exceed  2000,  although  not  more  than  thirty 
were  known  fifty  years  ago. 

3.  The  old  names  were  sometimes  barbarous,  absurd,  or  false,  im- 
plying incorrect  ideas. 

4.  The  nomenclature  of  the  French  chemists,*  is  eminently  use- 
ful in  the  study  of  the  salts. 

5.  Every  salt  consists  of  an  acid  and  a  salifiable  base,  and  the 
bases,  except  ammonia,  are  all  oxides  of  metals  or  of  inflammable 
bodies. 


*  See  page  35. 


320  SALTS. 

6.  The  genera  are  derived  from  the  acids  ;  the  species  from  the 
bases,  thus  all  that  contain  sulphuric  acid  are  sulphates ;  all  that  con- 
tain nitric  acid  are  nitrates,  &ic. 

7.  The  bases  are  the  oxides*  of  which  there  are  three  divisions  ;  the 
alkalies,  the  earths,  and  the  other  metallic  oxides. 

8*  Every  base  that  combines  with  acids,  furnishes  a  species  ;  thus 
sulphuric  acid  with  potassa,  soda,  and  ammonia  forms  a  sulphate  of 
each  of  those  bases. 

9.  The  termination  ate,  corresponds  with  the  acid,  whose  termina- 
tion is  in  ic,  and  the  termination  ite,  with  the  acid  whose  termination  is  in 
ous  ;  thus,  sulphuric  acid  gives  sulphates  ;  sulphurous  acid  sulphites. 

10.  There  are  some  acids  containing  less  oxygen  than  those  that 
terminate  in  ous  ;  in  such  case,  the  word  hypo  is  prefixed  ;  thus  we 
have  hypo-sulphurous  acid,  hypo-nitrous  acid,  giving  also  salts  that 
are  called  hypo-sulphites,  and  hypo-nitrites. 

11.  It  was  formerly  supposed,  that  there  is  sometimes  an  excess  of 
acid  in  a  salt,  in  which  case,  the  preposition  super  or  hyper  was  pre- 
fixed ;  and  on  the  other  hand,  that  there  is,  in  particular  cases,  a  de- 
ficiency of  acid  or  an  excess  of  base,  and  then  the  preposition  sub 
was  prefixed  ;  thus,  there  was  a  super-sulphate  of  potassa.  and  a  sub- 
carbonate  of  potassa. 

Now,  salts  with  excess  of  acid  are  distinguished  by  the  prefix, 
bis  or  bi;  thus  we  have  fo'-sulphate  and  6i-carbonate  of  potas- 
sa ;  because  in  these  salts,  there  is  just  twice  as  much  acid  as  in 
the  carbonates  of  the  same  base.  In  some  salts,  the  double  propor- 
tion is  again  doubled,  and  then  the  word  quadro  is  prefixed  ;  thus 
there  is  oxalate,  5w-oxalate  and  quadr-oxalate  of  potash,  implying 
one,  two,  and  four  equivalents  of  the  acid  to  one  of  the  base.  The 
word  super  is  now  banished  from  the  nomenclature  of  salts  ;f  but 
sub  is  still  retained  by  some,  where  there  are  two  or  more  propor- 
tions of  the  base.  But,  Dr.  Thomsonf  has  proposed  to  use  the 
Greek  numeral  words,  dis,  tris,  tetrakis,  to  denote  the  proportions  of 
base  in  a  sub-salt ;  thus,  6?i-sulphate  of  alumina  contains  one  propor- 
tion of  acid  and  two  of  the  earth,  but  this  nomenclature  has  not  yet 
obtained  general  currency. 

12.  Salts  are  generally,  but  not  always  sapid. — The  first  idea  was 
derived  from  common  salt ;  but  many  earthy  salts  are  insipid,  e.  g. 
sulphate  of  lime,  carbonate  of  lime,  &c.  and  such  salts  are  generally 
insoluble. 

13.  Salts  are  generally,  but  not  universally  soluble  in  water  ;  the 
alkaline  salts  are  all  soluble,  but  earthy  and  metallic  salts  have  some- 
times one  character  and  sometimes  the  other.     A  salt  is  said  to  be 

*  Ammonia  excepted. 

i  It  may  be,  and  often  is  still  used  in  a  vague  and  popular  sense. 
}  Dr.  Thomson  has  introduced  the  word  sesqui,  where  there  is  supposed  to  be  a 
half  of  an  equivalent. 


SALTS— SULPHATES.  321 

insoluble,  if  it  requires  more  than  1000  parts  of  water  for  its  solu- 
tion. 

14.  Incombustible,  with  a  few  exceptions. 

15.  Crystallizable,  either  by  natural  or  artificial  processes. 

16.  Saturation  between  acid  and  base  is  determined — 

(a.)  By  the  taste,  which,  when  there  is  one  equivalent  of  each, 
becomes  saline,  or  at  least,  ceases  to  be  acid  or  alkaline. 


'.^  By  the  absence  of  any  effect  on  test  colors. 

c.)  In  the  case  of  a  carbonate;  by  the  cessation  of  effervescence. 

d.)  A  scale  or  table  of  chemical  equivalents,  furnishes  at  once 
the  information  desired,  as  to  the  quantity  of  the  one  agent  necessary 
to  saturate  the  other. 

17.  Salts  precipitate,  if  they  are  insoluble  in  water,*  or  much  less 
soluble  than  their  constituent  principles — 

(a.)  In  powder,  as  sulphate  of  baryta. 

(b.)  In  crystals,  as  sulphate  of  potassa,  if  formed  from  concentra- 
ted acid  and  alkali. 

18.  If  soluble,  they  remain  in  solution,  as  most  alkaline,  and  many 
earthy  and  metallic  salts  do. 

19.  The  name  of  a  salt  expresses  its  composition,  and  the  knowl- 
edge of  the  composition  recals  the  name. 

20.  The  nomenclature  is  therefore  founded  upon  the  most  correct 
logical  principles. 

21.  The  salts  are,  on  the  whole,  very  important,  to  arts,  science, 
and  domestic  economy.     Some  of  them  exist  in  vast  abundance. 

SULPHATES  OF  ALKALIES  AND  EARTHS. — General  Characters. 

1.  Formed  by  sulphuric  acid  and  a  base. 

2.  Generally  crystallizable. 

3.  Not  decomposable  by  heat,  or  only  partially  so,  (except  the  sul- 
phate of  ammonia.) 

4.  Decomposable,  (with  the  same  exception,)  by  ignition  with 
charcoal,  being  converted  into  sulphurets. 

5.  Have  generally  a  bitter  taste,  if  any. 

6.  Decomposed  by  all  the  barytic  salts,  except  sulphate  of  baryta ; 
the  precipitate  is  insoluble  in  acetic  acid. 

7.  Precipitated  from  their  aqueous  solutions,  by  alcohol,  and  in 
general,  crystallized. 

SULPHATE  OF  POTASSA. 

1.  PREPARATION. 

(a.)  By  sulphuric  acid  and  dilute  solution  of  potassa,  or  of  carbo- 
nate of  potassa,  mingled  till  test  paper  is  no  longer  affected,  or  effer- 
vescence ceases. 

*  Supposing  the  bases,  or  perhaps  both  acids  and  bases,  to  have  been  previously 
in  aqueous  solution. 

41 


322  SALTS— SULPHATES. 

(b.)  Evaporation  gives  regular  crystals,  whose  form  is  that  of  six 
sided  prisms,  sometimes  crowned  by  six  sided  pyramids. 

2.  HISTORY. — Long   known,   and  had   formerly  a   multitude  of 
names,*  which  were  banished  when  it  received  its  present  denomina- 
tion. 

3.  PROPERTIES. 

(a.)  Taste,  acrid  and  bitter — sp.  gr.  2.29,  or  2.40,  easily  pulve- 
rized. 

(b.)  At  212°,  requires  five  times,  and  at  60°,  sixteen  times  its 
weight  of  water  for  solution. 

(c.)  Not  affected  by  the  air.  On  burning  coals,  or  red  hot  iron,  it 
decrepitates. 

(d.)  Contains  no  water  of  crystallization. 

4.  COMPOSITION. — Acid,  45.45  ;  potassa,  54.55,  or  acid,  1  propor- 
tion, 40 ;  potassa,  1  proportion,  48  =  88,  which  is  its  equivalent  number. 

5.  DECOMPOSITION. 

(a.)  By  acids. — Although  the  sulphuric  acid  has  a  stronger  affinity 
for  potassa,  than  any  other  acid  has,  still  the  nitric  and  muriatic  acids, 
in  large  quantities,  decompose  it  in  part ;  the  products  are  much  bi- 
sulphate  of  potassa,  and  some  nitrate  and  muriate  of  potassa. 

Not  owing  to  the  capriciousness  of  chemical  attraction,  but  accord- 
ing to  Berthollet,  to  the  influence  of  quantity,  compensating  for  infe- 
rior force  of  attraction. 

!b.)  By  barytic  and  strontitic  water,  attracting  the  sulphuric  acid, 
c.)  Also,  by  nitrate  and  muriate  of  lime,  by  double  elective  at- 
traction. 

(d.)  By  heating  it  with  charcoal  powder,  when  it  becomes  a  sul- 
phuret,  and  can  be  decomposed  in  the  palm  of  the  hand,  by  vinegar 
or  other  weak  acid,  thus  fulfilling  Stahl's  boast,  but  not  as  it  was  in- 
tended by  him,  that  others  should  understand  it. 

(e.)  Other  processes. — Saw  dust  substituted  for  charcoal,  and  py- 
roligneous  acid  for  the  vinegar,  and  the  acid  is  afterwards  decom- 
posed by  heat. — Dundonald. 

Sulphate  of  potassa,  100  parts,  chalk  100,  charcoal  50,  heat 
them — sulphuret  of  lime  is  formed,  and  the  alkali  being  liberated, 
may  be  obtained  by  lixiviation.f 

6.  USES,  &ic. — Called  in  the  shops,  vitriolated  tartar,  and  used 
as  a  purgative  or  alterative — dose,  half  an  oz.  or  less ;  the  effect  less 
transient  than  that  of  sulphate  of  soda.     The  sal  polycrest  of  the  old 
physicians  was  made  by  deflagrating  nitre  and  sulphur,  and  was  a 


*  Vitriolized  and  vitriolated  tartar,  sal  de  duobus,  arcanum  duplicatum,  sal  pol- 
ycrest, salt  of  Glazer,  vitriol  of  potash,  vitriolated  vegetable  alkali,  &c.  but  vitri- 
olated tartar  was  the  most  general  name.  Hence,  and  from  similar  cases,  the  ne- 
cessity of  the  new  nomenclature  of  the  salts. 

t  Ann.de  Chim.  Vol.  XIX. 


SALTS— SULPHATES.  323 

c&mpound  of  sulphate  and  sulphite  of  potassa.  The  finest  neutral 
crystals  of  this  salt  are  obtained  when  acid  predominates  in  the  mix- 
ture. 

Not  found  among  mineral  bodies,  but  exists  in  some  animal  fluids, 
and  in  the  ashes  and  juices  of  some  vegetables,  as  tobacco.* 

BI-SULPHATE  OF  POTASSA. 

1 .  PREPARATION. — By  heating  together  three  parts  of  sulphate  of 
potassa,  and  one  of  sulphuric  acid ;  discovered  by  Rouelle   senior  ; 
may  be  obtained  in  needle  formed  crystals,  and  even  in  six  sided 
prisms. 

2.  PROPERTIES. 

(a.)  Soluble  in  2  parts  of  water,  at  60°,  and  in  less  at  212°. 

(b.)  Melts  readily,  with  the  appearance  of  oil,  but  becomes  of  an 
opake  white  on  cooling ;  heated  for  a  long  time,  its  superfluous  acid 
is  dissipated,  and  it  becomes  sulphate  of  potassa. 

!c.)  Taste  acrid  ;  reddens  the  blue  test  colors. 
d.)  The  bi-sulphate  is  usually  obtained  in  the  process  for  nitric 
acid. 

(e.)  With  ice,  it  generates  cold.f  Of  little  use,  except  to  form  the 
sulphate,  which  is  done  by  neutralizing  the  excess  of  acid  by  chalk ; 
it  may  be  used  in  crystallizing  alum,  and  is  sometimes  employed  as 
a  flux. 

After  the  process  for  nitric  acid,  if  the  salt,  while  still  fluid,  is  pour- 
ed into  a  pan,  it  effloresces  most  beautifully  in  the  course  of  a  few 
months,  presenting  a  delicate  downy  coating  of  crystalline  filaments, 
which  make  their  way  over  and  down  the  sides  of  the  vessel ;  if  it 
is  glazed,  the  glazing  will  peal  off  and  leave  the  naked  biscuit. 

It  contains  two  proportions  of  sulphuric  acid,  and  one  of  potassa, 
40X2=80  acid,  -f  48  potassa  =  128  for  its  equivalent. 

SULPHATE    OF  SODA. 

1.  NAMES. — Named  Glauber's  salt,  after  a  German  chemist,  who 
discovered  it  in  the  residuum  of  the  process  for  muriatic  acid. 

2.  NATURAL  HISTORY. 

(a.)  Found  in  sea  water,  and  in  the  ashes  of  marine  vegetables, 
and  in  kelp. 

(b.)  In  the  earth,  near  ASTRACHAN.{ 

(c.)  In  salt  and  mineral  springs. 

(d.)  Often  effloresces  at  the  surface  of  the  ground,  upon  the  walls 
of  subterraneous  edifices  and  other  buildings. 


*•  Four.  III.  33.  t  Four.  Ill,  39.  t  Kirw.  Mfti 


324  SALTS— SULPHATES. 

(e.)  Found  in  the  ashes  of  old  wood,  and  in  some  plants,  particu- 
larly tamarisk.* 

(/.)  In  large  proportion  in  the  Glauberite  of  Spain. 

3.  PREPARATION. — By  saturating  a  solution  of  soda  or  its  carbo- 
nate with  sulphuric  acid,  but  the  quantity  produced  in  the  manufac- 
ture of  muriatic  acid,  and  chlorine,  and  that  can  be  made  from  sea 
water,  is  much  greater  than  can  be  consumed. 

4.  PROPERTIES. 

(a.)  Crystallizes  in  transparent  six  sided  prisms,  with  dihedral 
summits,  usually  striated  at  the  edges,  and  often  very  irregular. 

(b.)  Taste  bitter,  and  dissolves  easily  in  the  mouth ;  suffers  readily, 
the  watery  fusion ;  then  dries  and  melts,  with  the  true  igneous  fusion. 

(c.)  Effloresces  in  the  air — loses  half  its  weight,  and  thus  becomes, 
as  a  medicine,  twice  as  strong ;  by  a  high  heat,  a  part  of  the  acid  is 
driven  off. 

(d.)  Soluble  in  2.67  of  water  at  60°,  and  in  .8,  at  212  ;f  in  this 
respect,  strongly  contrasted  with  sulphate  of  potassa.  The  hot  solu- 
tion of  sulphate  of  soda,  crystallizes  by  cooling, {  and  when  the  quan- 
tity is  great,  the  crystals  are  very  large,  sometimes  half  a  yard  in 
length,  and  several  inches  in  diameter. § 

5.  COMPOSITION. — When  anhydrous, 

Acid,     55.55  or  1  proportion  40 
Soda,     44.45  or  1         "         32 

100.  72  its  representative  number. 


*  Four.  Ill,  42. 

t  In  judging  of  the  solubility  of  a  salt,  we  must  not  put  the  salt  into  water,  and 
expose  that  water  directly  to  heat,  but  immerse  the  vessel  containing  the  salt  in  a 
water  bath,  in  which  the  thermometer  is  placed. 

t  At  70°,  water  dissolves  nearly  half  its  weight,  twice  its  weight  at  88°,  and  3.2  of 
its  weight  at  106°,  at  any  higher  degree,  some  of  the  salt  is  deposited  in  opake  anhy- 
drous crystals,  so  that  it  grows  less  soluble  with  more  heat. — Turner. 

§  If  the  saturated  boiling  solution  of  this  salt  be  made  with  care  in  a  matrass  or 
flask,  and  free  from  agitation,  it  may  be  reduced  to  the  temperature  of  the  air  with- 
out crystallizing.  Close  the  vessel  by  a  stop  cock  at  the  top,  or  a  good  cork,  the  in- 
stant before  it  is  withdrawn  from  the  fire,  and  while  still  boiling.  Sometimes  on  open- 
ing or  on  agitating  the  solution,  and  always  on  throwing  in  a  crystal,  (any  crystal  or 
solid  will  do,  but  better  one  of  the  same  salt,)  nearly  the  whole  fluid  will  rapidly  crys- 
tallize, and  the  temperature  will  rise  considerably.  The  balance  offerees  between 
cohesion  and  repulsion  is  disturbed  by  agitation,  or  by  a  crystal  affording  a  nucleus. 
The  pressure  of  the  atmosphere  acts  only  as  a  disturbing  force,  and  any  other  disturb- 
ing forces  produce  the  concretion ;  for  it  happens  in  vacuo  if  a  crystal  be  dropped 
in.  Mr.  Graham,  (Phil.  Mag.  New  Series,  Vol.  IV,  p.  215,)  has  discovered  that 
a  saturated  solution  of  sulphate  of  soda,  placed  over  mercury,  previously  heated 
to  110°  or  120°,  will  cool  without  crystallizing,  but  that  if  a  bubble  of  air,  or 
of  any  gas,  especially  of  those  that  are  soluble  in  water,  or  a  portion  of  any  fluid 
that  attracts  water,  as  alcohol,  be  thrown  up  into  the  solution,  it  will  immediately 
crystallize.  Hence  it  is  concluded  that  the  influence  of  air  in  causing  the  crystal- 
lization in  this  well  known  experiment,  is  owing  to  the  solution  of  a  portion  of  it, 
which  thus  deprives  the  salt  of  a  part  of  its  water,  and  causes  the  crystallization  to 
begin. 


SALTS— SULPHATES.  325 

The  crystals, 

Acid,     24.70  or  1  proportion  =40 
Soda,     19.75         1          "  =32 

Water,  55.55       10         "          =90 

100.  162  its  equivalent  number. 

6.  DECOMPOSITION. 

(a.)  By  combustibles,  especially  charcoal ;  the  same  as  that  of  sul- 
phate of  potassa.  Immense  quantities  are  produced  in  making  muri- 
atic acid,  and  in  other  manufactures  ;  therefore  its  cheap  and  effectual 
decomposition  is  an  object  of  vast  importance  for  the  sake  of  the  soda. 

(b.)  Potassa  will  do  it.  but  the  price  of  labor  forbids,  although 
soda  is  dearer  than  potash. 

(c.)  Decomposed  (via  humida,)  by  no  acid,  but  it  dissolves  readily 
in  the  nitric,  muriatic  and  sulphuric  acids,  producing  cold.  4  parts 
sulphuric  acid  with  5  of  this  salt  produce  47°  of  cold ;  2  parts  nitric 
acid  with  2  water  and  3  of  this,  produce  more  cold  than  the  last  mix- 
ture ;  5  muriatic,  and  8  of  this  salt,  form  a  considerably  powerful 
mixture. 

.)  Baryta  and  strontia  decompose  it,  taking  its  acid. 
SES. — It  is  the  most  common  domestic  cathartic,  and  is  called  salts; 
dosel  oz.  perhaps  more,  often  1 J  oz.   Used  also  in  small  diluted  doses, 
as  a  diuretic  and  aperient.   The  effloresced  salts  must  be  given  in  half 
the  quantity.     It  is  now  used  in  the  manufacture  of  glass,  p.  280  (b.) 

BISULPHATE    OF    SODA.      *      ' 

Formed  by  adding  sulphuric  acid  to  a  hot  solution  of  sulphate  of  soda; 
product,  large  rhomboidal  crystals  ;  efflorescent,  soluble  in  twice  their 
weight  of  water  at  60° ;  lose  their  excess  of  acid  by  heat. — Henry* 

SULPHATE    OF    AMMONIA. 

1.  HISTORY,   NAME,  &tc. — Discovered  by  Glauber,  who  called 
it  secret  sal  ammoniac  ;  other  names — vitriolated  ammoniac,  vitriol- 
ated  volatile  alkali,  &c.     Found  in  the  vicinity  of  volcanos,  and  in 
the  waters  of  the  Tuscan  lakes ;  also  in  the  ashes  and  soot  of  pit 
coal.* 

2.  PREPARATION. — By  mingling    sulphuric   acid   88  parts,  and 
compact  carbonate  of  ammonia  100  parts,  to  mutual  saturation,  or 
by  decomposing  muriate  of  ammonia,  by  sulphuric  acid. 

3.  PROPERTIES. 

(a.)  The  crystals  are  long  six  sided  prisms,  crowned  with  six 
sided  pyramids ;  sometimes  in  plates,  silky  fibres,  or  clusters  of 
needles. f 


(" 

u.. 


*  It  is  not  probable  that  the  ammonia  exists  in  the  coal,  but  the  nitrogen  of  the 
air  and  the  hydrogen  of  the  coal  form  the  ammonia ;  the  oxygen  of  the  air,  with  the 
sulphur  of  the  coal,  forms  the  sulphuric  acid,  and  this  is  doubtless  the  origin  of  the 
sulphate  of  ammonia  in  the  soot  and  ashes.  t  Tour.  Vol.  Ill,  p.  55. 


326  SALTS—SULPHATES. 

b.)  Taste  sharp  and  bitter. 

c.)  Solubility  at  60°  ;  water  1,  salt  2  ;  at  212°,  equal  parts. 

d.)  During  its  solution  it  produces  cold. 

e.)  Little  affected  by  the  air,  or  slightly  efflorescent. 

/.)  Heated,  suffers  watery  fusion,  sublimes  in  part,  and  is  then 
sour,  and  reddens  vegetable  blues.  By  a  still  higher  heat,  com- 
pletely decomposed,  and  resolved  into  nitrogen,  water,  and  sulphu- 
rous acid. 

5.  COMPOSITION. 

Acid,         53.1     or     1  propor.  =40 
Ammonia,  22.6  1       "        =17 

Water,       24.3  2       "        =18 

100.0  75  its  equivalent  number. 

If  water  be  subtracted,  it  leaves  57  for  anhydrous  sulphate,  which 

is  known  only  in  theory.     Dr.  Thomson  admits  but  one  proportion 

of  water,  in  the  crystallized  salt,  which  would  reduce  its  equivalent 

to  66. 

6.  DECOMPOSITION. 

The  nitric  and  the  muriatic  acids  decompose  about  J  of  the  salt. 
Potassa  and  soda,  baryta,  strontia  and  lime,  liberate  the  gas 
ammonia,  forming  a  sulphate  of  the  base.     Sulphate  of  soda,   and 
sulphate  of  ammonia,  when  mingled,  form  a  triple  crystallizable  salt.* 
(c.)  Deflagrates  with  melted  nitre,  being  resolved  into  water  and 
nitrogen. 

SULPHATE    OF    LIME. 

1.  PREPARATION,  NATURAL  HISTORY,  &c. — Formed  by  the  mu- 
tual action  of  diluted  sulphuric  acid  and  marble,  or  chalk,  or  by  the 
same  acid  and  any  soluble  calcareous  salt,  or  lime  water;  the  sul- 
phate precipitates. 

2.  PROPERTIES. 

Melts  before  the  blowpipe,  and  in  furnace  heats. 
Solubility  in  cold  water,  500  parts  to  1,  in  450  at  212°,  and 
crystallizes  on  cooling.     Soluble  entirely  in  dilute  nitric  acid. 

(c.)  Causes  waters  to  be  hard, — decomposing  the  soap  that  is 
mingled  with  them  ;  the  acid  unites  with  the  alkali,  and  the  oil  with 
the  earth,  to  form  an  earthy  soap  ;  by  adding  solution  of  soap  to  so- 
lution of  sulphate  of  lime,  this  effect  is  manifested. 

(d.)  Thrown  down  by  alcohol  from  its  aqueous  solution. 

(e.)  Decomposed  by  boiling  with  baryta,  strontia,  potassa  and  soda, 
and  by  their  carbonates,  or  at  least  by  those  of  the  fixed  alkalies ; 
see  those  articles. 


Th.  Ill,  362. 


to 


SALTS— SULPHATES.  327 

(/.)  Insipid  and  harmless ;  sp.  gr.  of  the  native  salt  about  2.26  to 
2.31. 

3.  COMPOSITION. — According  to  Dalton,  58.60  acid,  41. 40  base. 
Berzelius  and  Thomson  58.  and  42.     Dr.  Henry  thinks  its  true  con- 
stitution is,  Acid,  58.42,  or  1  proportion,  -         -     =  40 
Lime,  41. 58,  or  1         "  -     -28 


100.00  68 

Crystallized  sulphate  of  lime  is  composed  of, 
Sulphate  of  lime,  79.07,  or  1  proportion,  (anhydrous,)  68 
Water,         -         20.93,  or  2  "  18 


100.00  86 

4.    USES  AND  MISCELLANEOUS  REMARKS. 

(a.)  The  native  salt  is  abundant,  in  the  form  of  alabaster,  gypsum, 
or  plaster  stone,  selenite  crystals,  &c.  Found  in  the  ashes  of  vege- 
tables, in  the  sea,  and  in  many  natural  waters ;  producing  incrusta- 
tions upon  the  pans  of  the  salt  boilers.* 

There  is  a  native  variety  without  water,  called  the  anhydrite,  but 
it  is  rare,  and  its  properties  are  different  from  those  of  the  common 
kind.f 

Sb.)  Heated,  it  loses  weight  .22,  and  if  in  a  retort,  water  may  be 
ected. 

(c.)  Exhibits  a  false  appearance  of  boiling,  in  consequence  of  the 
escape  of  the  water ;  this  is  best  shewn  in  a  glass  retort,  with  the  la- 
mellated  variety ;  it  may  be  seen  in  a  crucible  with  a  forge  heat. 

(d.)  Thus  prepared  for  statuary  and  stucco  work.  Heat  the  plas- 
ter thoroughly,  pulverize  it  fine,  mix  with  a  little  good  quick  lime  in 
fine  powder,  and  form  into  a  paste  with  water. 

(e.)  To  copy  a  medal  or  coin,  pour  the  paste  into  a  box,  oil  the 
surface  of  the  medal  to  prevent  adhesion,  and  brush  it  over  with  the 
cream  of  the  plaster  to  prevent  air  holes ;  then  impress  it  upon  the 
paste  and  let  it  harden. 

(f.)  To  copy  a  face,  living  or  dead,  or  a  statue ;  the  process  is 
the  same,  only  laying  the  figure  on  a  table,  oiling  the  surface,  and  if  a 
living  person,  putting  paper  tubes  in  the  nostrils,  tying  the  hair  back, 
and  pouring  on  the  plaster  of  the  consistence  of  a  thick  cream.  The 
muscles  are  kept  composed,  and  in  about  20  minutes,  the  cast  will 
grow  firm,  when  it  is  removed.  After  forming  the  concave  copy,  the 
convex  is  cast  in  it,  and  any  mistakes  are  corrected  or  additions  made  ; 
then  a  new  concave  is  made  upon  this  and  serves  as  a  permanent 
mould  ;  statues  are  cast  in  parts  and  then  joined.  For  stucco  work, 


*  And  in  the  boilers  of  the  steam  boats,  that  use  salt  water. 

t  It  is  found  to  be  much  more  common  than  was  formerly  supposed. 


328  SALTS— SULPHATES. 

the  plaster  is  cast  in  moulds,  or  figured  on  the  spot  to  which  it  is  ap- 
plied. 

Sometimes  used  to  adulterate  flour. 

Discovered  by  weighing  a  given  measure,  by  grittiness  be- 
tween the  teeth,  by  alcohol  throwing  it  down  from  water  that  has  been 
boiled  on  the  flour,  by  the  tests  for  lime  and  sulphuric  acid,  by  burn- 
ing the  flour  in  the  open  air,  and  examining  the  residuum  and  by 
forming  heavy  bread. 

Besides  the  uses  of  this  salt  for  statues,  &c.  it  is  employed  in  -cer- 
tain proportions  with  common  lime  plaster,  to  give  it  firmness  and 
beauty,  and  such  walls  will  bear  washing  and  cleaning  with  soap.  It 
is  largely  and  most  advantageously  employed  in  agriculture  as  a 
manure,  on  sandy  soils  and  grass  lands. *  It  is  extensively  used  in 
Switzerland,  but  very  little,  if  at  all,  in  Great  Britain.  It  need  not 
be  burned,  but  merely  pulverized.  At  Paris,  and  in  Minorca,  it  is 
employed  in  building  houses.  Abundant  in  Nova  Scotia,  and  in  many 
of  the  Western  American  States ;  a  very  beautiful  transparent  va- 
riety is  found  at  Lockport,  and  the  compact  variety  exists  extensive- 
ly in  other  places  in  the  state  of  New  York. 

SULPHATE    OF    BARYTA. 

1.  NAME,  &c, 

(a.)  The  native  mineral  formerly  called  ponderous  spar ;  its  sp. 
gr.  being  from  4.3  to  4.7. 

(b.)  Its  composition  first  ascertained  by  Ghan. 

2.  NATURAL  HISTORY. 

(a.)  Found  native,  in  almost  every  country,  particularly  in  metal- 
lic veins,  of  which  it  often  forms  the  gangue ;  it  is  frequently  amorphous, 
compact  or  granular,  and  of  a  pure  white,  or  red,  brown,  yellow,  &c. 

(b.)  Often  crystallized,  or  fibrous,  translucent,  transparent  or 
opake.f 

3.  PREPARATION. — By  mingling  barytic  water  or  any  soluble  salt 
of  baryta,  with  sulphuric  acid  or  any  soluble  salt  containing  it ;  there 
is  an  immediate  dense  precipitate. 

4.  PROPERTIES. 

(a.)  By  heat,  the  foliated  natural  sulphate  decrepitates,  and  melts 
under  the  blowpipe,  at  about  35°,  Wedg. 

(b.)  Tasteless  and  inodorous,  insoluble  in  water ;  or  requires  ac- 
cording to  Kirwan,  43,000  parts  of  water. 

*  The  popular  opinion  that  it  will  not  answer  near  the  sea,  appears  to  be  erroneous, 
as  was  proved  by  the  late  Mr.  M.  Rogers,  at  his  place,  near  Stamford,  Conn, 
where,  as  I  heard  him  say,  it  produced  the  most  striking  effects  on  land  washed  by 
the  salt  water.  Dr.  Black  says  its  effects  last  two  years,  and  he  asserts,  contrary  to 
our  impressions  in  this  country,  that  it  is  most  efficacious  on  strong  and  rich  lands. 

t  Found  sometimes  in  sandstone,  in  Scotland ;  rarely,  in  the  same  country,  in 
granite,  in  the  place  of  the  felspar  ;  occasionally  in  the  interior  of  Scotch  agates,  and 
in  the  ludus  helmontii,  of  England. 


SALTS— SULPHATES.  329 

(c.)  Soluble  in  concentrated  sulphuric  acid,  especially  if  boiling, 
but  again  precipitated  by  water.* 

(d.)  Decomposed  by  ignition  with  charcoal ;  its  oxygen  is  separated 
in  the  form  of  carbonic  acid,  and  sulphuret  of  barium  is  left. 

(e.)  Pulverized,  kneaded  up  with  flour  and  water,  formed  into  a 
thin  cake  and  exposed  to  ignition,  it  becomes  phosphorescent  in  the 
dark.f 

5.  COMPOSITION. — Dr.  Henry,  after  citing  several  analyses,  con- 
cludes that  the  true  composition  is, 

Acid,    33.90,  1  proportion,        -  40 

Earth,  66.10,  "  -    78 

100.00  11 8,  its  equivalent. 

As  baryta  is  used  to  separate  sulphuric  acid  from  all  its  combina- 
tions, this  salt  is  very  important  in  analysis.  The  quantity  is  deter- 
mined by  weighing  the  precipitate,  previously  washed  and  dried,  and 
allowing  33.9  per  cent,  of  its  weight,  "  for  real  sulphuric  acid,"  thus 
shewing  the  quantity  in  any  sulphate.  J  Sulphuric  acid  or  any  solu- 
ble sulphate  occasions  a  sensible  precipitate  in  a  solution  containing 
sVo  o  °f  baryta,  or  of  any  of  its  soluble  salts.§ 

6.  DECOMPOSITION. — The  mode  by  charcoal  has  been  already 
mentioned. 

Sa.^  Not  decomposed  by  any  acid  or  alkali.\\ 
b.)  Readily  by  double  elective  attraction,  with  carbonate  of  po- 
tassa,  or  of  soda,  or  ammonia, IT  after  long  continued  boiling. 

(c.)  But  much  more  readily,  by  ignition  with  the  carbonate  of  an 
alkali. — Mix  pure,  decrepitated  and  pulverized  sulphate  of  baryta, 
with  twice  its  weight  of  dry,  pure  carbonate  of  fixed  alkali,  and  ex- 
pose them  in  a  crucible  to  a  violent  heat.  A  double  decomposition 


*  Easily  shown  by  adding  sulphuric  acid  to  solution  of  baryta,  or  any  of  its  soluble 
salts ;  the  precipitate  will  be  redissolved  by  more  sulphuric  acid,  and  then  thrown 
down  by  water,  and  thus  it  may  be  alternately  redissolved  and  precipitated  by  acid 
and  water. 

t  First  observed,  in  the  variety  called  Bologna  stone,  by  an  Italian  shoemaker, 
named  Vincen/o  Casciarolo.  This  man  found  a  Bologna  stone  at  the  foot  of  mount 
Paterno,  and  its  brightness  and  gravity  made  him  suspect  that  it  contained  silver. 
Having  heated  it  to  extract  the  silver,  he  observed  that  it  was  afterwards  luminous 
in  the  dark,  and  on  repeating  the  experiment,  it  constantly  succeeded.  It  is  evident 
that  by  the  calcination,  it  must  be  converted,  at  least  in  part,  into  sulphuret.  Prof. 
Olmsted  informs  me,  that  a  granular  sulphate  of  baryta  from  North  Carolina,  (Crow- 
der's  mountain,)  when  heated,  phosphoresces  with  a  clear  white  light. 

t  Henry,  10th  Ed.  Vol.  I,  p.  604.  §  Thenard,  III,  171. 

||  Fourcroy  asserts,  (III,  32,)  that  the  phosphoric  and  boracic  acids,  decompose  it 
by  ignition. 

IT  After  boiling  for  two  hours,  about  one  fourth  of  it  will  be  found  to  be  decomposed, 
and  the  result  will  be  carbonate  of  baryta,  sulphate  of  the  alkali,  and  undecomposed 
sulphate  of  baryta. 

42 


330  SALTS— SULPHATES. 

results,  and  carbonate  of  baryta  and  sulphate  of  alkali  remain  mixed 
in  the  crucible ;  wash  out  the  soluble  sulphate  with  water,  dissolve 
the  carbonate  of  baryta  in  muriatic  acid  ;  decompose  it  by  the  car- 
bonate of  an  alkali,  and  thus,  after  strong  ignition,  especially  in  con- 
tact with  charcoal  powder,  the  pure  earth  will  be  obtained. 

(d.)  Native  carbonate  of  baryta  dissolves  in  sulphuric  acid,  with 
a  very  slow  and  scarcely  perceptible  effervescence. 

7.  USES. 

(a.)  To  afford  baryta  by  its  decomposition,  and  for  the  prepara- 
tion of  a  phosphorescent  substance. 

(b.)  It  has  been  used  in  the  manufacture  of  porcelain,  particularly 
by  the  late  Mr.  Wedgwood.* 

(c.)  The  artificial  sulphate,  under  the  name  of  permanent  white,  is 
applied  in  painting  in  water  colors,  and  is  the  most  delicate  and  per- 
manent white  known,  f  The  carbonate  is  employed  for  the  same 
Qose.  Either  of  them  may  be  used  with  advantage  in  labelling 
es  in  a  laboratory,  where  acid  vapors  are  so  apt  to  destroy 
common  writing  ink.J 

[d.)  The  sulphate  of  baryta  is  the  only  salt  of  this  earth  that  is  not 
poisonous. — If  the  carbonate,  which  is  a  virulent  poison,  has  been 
swallowed,  diluted  sulphuric  acid  would  therefore  be  an  antidote  ; 
and  if  any  soluble  salt  of  baryta  has  been  taken,  a  solution  of  sulphate 
of  soda  or  other  alkaline  or  earthy  sulphate  would  be  the  best  remedy. § 

SULPHATE    OF    STRONTIA. 

1.  DISCOVERY. — By  Dr.  Hope  and  Mr.  Klaproth,  about  the  year 
1793. 

2.  NATURAL  HISTORY. 

(a.)  Exists  naturally  in  considerable  abundance  ;  usually  called  ce- 
lestine,  from  a  delicate  tinge  of  sky  blue,  which  it  frequently  has ; 
first  observed  at  Strontian,  in  Scotland  ;  found  at  Bristol,  England ; 
at  Bouvron,  France,  and  at  Montmartre,  near  Paris ;  in  splendid 
crystals  in  Sicily ;  also  very  beautiful  at  Put-in-Bay,  Mackinaw,  and 
Detroit,  on  the  Great  Lakes,  and  at  Lockport,  N.  Y. 

(b.)  Found  crystallized,  massive,  or  in  veins,  "composed  of  nee- 
dles, or  very  fine  rhomboidal  prisms;"  sometimes  foliated,  fibrous,  or 
granular ;  occasionally  in  sulphur  beds. 

*  He  employed  it  in  what  was  called  the  jasper  ware,  which,  for  a  long  time,  was 
made  by  Mr.  Wedgwood  alone ;  but  the  secret  having  been  discovered  and  sold  by 
a  faithless  servant,  both  the  price  and  beauty  of  the  vessels  were  soon  much  re- 
duced by  inferior  artists. — Parkes*  Essays,  Vol.  I, p.  317.  t  Parkes. 

t  Artificial  sulphate  mingled  with  lampblack,  painter's  oil  and  spirits  of  turpentine, 
for  light  colored  bottles,  drawers,  &c.  without  the  lampblack,  for  black  bottles,  &c. — 

c.u.  s. 

§  Thenard,  Vol.  Ill,  172,  says,  "  Le  sulfate  de  bavyte  est  employe  en  Angleterre 
eomme  mort-aux-rats."  This  appears  to  be  a  mistake;  th«  carbonate  is  the  sub- 
stance actually  used  for  this  purpose. 


SALTS— SLPHATES.  33 1 

(c.)  Frequently  confounded  with  sulphate  of  baryta,  but  easily 
distinguished  from  it,  by  its  sp.  gr.  which  is  3.85 ;  it  is  always  below 
4.  and  sulphate  of  baryta  always  above  4.25 

3.  PREPARATION. 

(a.)  By  mingling  sulphuric  acid  and  strontian  water,  when  it  is 
precipitated  in  the  form  of  a  white  and  tasteless  powder. 

(b.)  Or  by  mixing  any  soluble  form  of  strontia,  with  any  soluble 
sulphate. 

4.  PROPERTIES. 

(a.)  Tasteless  and  inodorous ;  nearly  insoluble;  requiring  3000 
or  4000  parts  of  cold,  or  3840  of  boiling  water. 

(b.)  Dissolved  in  boiling  sulphuric  acid,  and  thrown  down  again 
by  water  ;  or  in  the  additional  mode  named  under  sulphate  of  baryta, 
4.  (c.)  note. 

5.  COMPOSITION. 

Acid,     42 4-  earth  58=1 00. — Wollaston. 

"        46 -f     "     54=100.— Fauquelin. 

43  4-     "     57  =  100.— Stromeyer. 

According  to  Dr.  Thomson,  it  is  composed  of  1  proportion  of 
strontia  52,  and  one  of  acid  40=92  for  its  equivalent,  and  this  would 
require  this  salt  to  consist  of  43.47  acid,  and  56.53  base. 

6.  DECOMPOSITION. 

(a.)  JVb  acid  decomposes  it,*  nor  does  air  affect  it.  At  a  high 
temperature  it  melts. 

(b.)  JVb  base  except  baryta  can  separate  its  acid;  but  carbonates  of 
the  fixed  alkalies  decompose  it  with  the  aid  of  heat. 

(c.)  Decomposed  by  ignition  with  charcoal,  in  the  same  manner 
as  sulphate  of  baryta  is.  It  has  not  been  applied  to  any  use.f 

SULPHATE    OF    MAGNESIA. 

1.  NAME  AND  PREPARATION. 

(a.)  That  of  the  shops,  called  Epsom  Salts,  from  a  mineral 
spring  at  Epsom,  in  Surrey,  (Eng.)  where,  mixed  with  some  sulphate 
of  soda,  it  was  first  obtained  by  Dr.  Grew,  A.  D.  1675.  But  Dr. 
Black  first  distinguished  it  from  Glauber's  salt,  with  which  it  had,  till 
his  time,  been  confounded. 

(b)  Formed,  by  dissolving  the  carbonate  of  magnesia,  or  calcined 
magnesia,  in  sulphuric  acid,  somewhat  diluted ;  it  is  then  evaporated 
and  crystallized. 

(c.)  Strong  sulphuric  acid  and  calcined  magnesia,  produce  great 
heat,  and  sometimes  light ;  but  this  acid  evolves  no  heat  with  the 
carbonate,  because  the  gas  carries  it  away. 

*  The  phosphoric  and  boracic  effect  its  decomposition,  if  aided  by  a  red  heat—* 
Fourcroy,  Vol.  Ill,  p.  48. 

t  Except  in  pyrotechny,  for  preparing  the  nitrate  of  strontia  an  ingredient  of  red 
re.-3.  T. 


332  SALTS -SULPHATES 

2.  PROPERTIES. 

(a.)  Crystals  four  sided  prisms,  with  quadrangular  pyramids, 
having  dihedral  summits.* 

The  prismatic  form,  according  to  Mr.  Brooke,  is  a  right  rhom- 
boidal  prism,  of  90°  30,  and  89°  30. 

(b.)  The  Epsom  salt  of  the  shops  is  in  the  form  of  confused  needle 
like  crystals. 

(c.)  When  pure,  unchanged  in  the  air;  but  sometimes  deliques- 
cent, from  mixture  with  the  muriate. 

(d.)  Suffers  aqueous  fusion  at  low  redness  ;  and  loses  about  half 
its  weight,  but  is  not  volatilized,  except  a  little  of  the  acid. 

(e.)  Soluble  at  60°,  in  1  part  of  water,  in  f  of  its  weight  at  212°, 
the  water  is  expanded  J. 

(/.)  Solution  precipitated  by  carbonates  ofpotassa  and  soda,  (see 
those  articles.)  Equal  weights  of  the  salts,  in  equal  weights  of  boil- 
ing hot  water  ;  or,  crystallized  sulphate  4  parts,  carbonate  of  potassa 
3  parts,  in  solution  ;  100  grains  dry  sulphate  give  about  71  carbonate 
of  magnesia,  or  33.  pure  earth. 

(g.)  The  carbonate  is,  in  this  case,  preferable  to  the  bi-carbonate 
of  an  alkali,  because  abundance  of  carbonic  acid  suspends  the  mag- 
nesia ;  heat  would  however,  eventually  throw  down  a  precipitate. 

(h.)  Carbonate  of  ammonia  does  not  precipitate  the  earth,  unless 
heat  is  applied. 

(i.)  Barytic,  strontitic,  and  lime  water  throw  down  a  mixed  pre- 
cipitate of  carbonate  of  magnesia  and  a  sulphate  of  the  other  earth. 

(y.)  Decomposed  by  charcoal  at  ignition  ;  producing  a  sulphuret, 
which  is,  however,  feeble  in  its  properties. 

(&.)  Jit  a  high  heat  completely  fusible,  but  without  decomposition. 

(I.)  Taste  bitter,  but  less  disgusting  than  that  of  sulphate  of  soda. 

(m.)  JLn  excellent  cathartic;  dose,  6  or  8  drachms,  dissolved  in 
water;  and,  by  many,  preferred  to  Glauber's  salts. 

3.  COMPOSITION. — 1  proportion  of  magnesia     20  33.04 

1         «         sulphuric  acid,  40  66.96 

its  equivalent  number,  60  100.00 

The  crystals  contain, 

Magnesia,  16.  or  1  proper.  20 
Acid,  32.57  or  1  "  40 
Water,  51.43  or  7  "  63 

100.00  123  the  equivalent  for  the 

crystals. 

*  For  some  varieties  of  the  crystals,  see  Henry,  Vol.  I,  p.  621. 


SALTS— SULPHATES.  333 

(a.)  With  pure  ammonia,  a  part  of  the  earth  is  precipitated  ;  by 
evaporation  a  triple  salt,  called  the  amrnoniaco-raagnesian  sulphate, 
is  obtained,  consisting  of 

Sulphate  of  magnesia,  1  proportion  60 

Sulphate  of  ammonia,  1         "  57 

Water,  7         "  63 

180  its  equivalent  number. 

(b.)  Ji  compound  sulphate  of  magnesia  and  soda  is  obtained,  by 
evaporating  the  bittern  of  sea  water ;  it  crystallizes  in  transparent 
rhombs,  and  consists,  according  to  Dr.  Murray's  analysis,  of  sul- 
phate of  magnesia  32,  sulphate  of  soda  39,  and  water  29 ;  and  its 
proportions  are  very  nearly  those  of  1  equivalent  of  sulphate  of  mag- 
nesia 60,  1  of  sulphate  of  soda  72,  and  6  of  water,  54=186  for  its 
equivalent  number.  It  is  a  cathartic,  not  disagreeable  to  the  taste, 
and  is  sold  at  Lymington,  England.* 

(c.)  A  sulphate  of  potassa  and  magnesiaf  is  obtained,  when  1 
equivalent  of  sulphate  of  magnesia  and  1  of  sulphate  of  potassa  are 
mixed ;  they  crystallize  with  6  of  water,  and  there  is  a  double  salt 
of  1  equivalent  of  sulphate  of  magnesia,  and  1  of  sulphate  of  ammo- 
nia, with  8  of  water,  which  is  obtained  by  spontaneous  evaporation 
of  the  mixed  solutions. 

4.  ORIGIN  OF  SULPHATE  OF  MAGNESIA. 

(a.)  Found  abundantly  in  sea  water,  ancf  obtained  from  the  bit- 
tern, after  the  evaporation  for  crystallizing  common  salt ;  it  is  boiled 
down,  until,  on  cooling,  in  clear  and  cold  weather,  it  affords  the  sul- 
phate of  magnesia,  in  acicular  crystals,  in  the  proportion  of  4  or  5 
parts  to  100  of  common  salt,  obtained  from  the  same  water;  or  sul- 
phate of  iron  is  added,  to  decompose  the  muriate  of  magnesia,  and 
thus  increase  the  quantity  of  sulphate.  J 

(b.)  Manufactured  from  magnesian  minerals,  especially  the  mag- 
nesite  ;  1.500,000  Ibs.  are  made  annually  in  Baltimore,  from  a  mag- 
nesite  found  near  Chester,  Penn.§ 

(c.)  Found  native  and  crystallized,  in  remarkable  quantity,  in  a 
great  cave,  at  Corydon,  Indiana ;  also  in  many  other  limestone  cav- 
erns, in  Kentucky,  Virginia,  and  Tennessee,  &c. 

(d.)  Effloresces  occasionally  on  brick  walls. 

(e.)  Formed  by  the  decomposition  of  rocks,  which  contain  mag- 
nesia, and  sulphuret  of  iron ;  the  latter  affords  the  sulphuric  acid, 
which  combines  with  the  magnesia,  and  effloresces,  and  is  extracted 
by  a  process,  for  which  see  Thenard,  5th  Ed.  Vol.  Ill,  p.  169. 

*  Murray,  6th  Ed.  Vol.  II,  p.  94,  and  Edinburgh  Trans. 

t  See  Phil.  Trans.  1822,  p.  455,  also  Henry,  10th  Ed.  Vol.  I.  p.  625. 

t  See  muriate  of  magnesia. 

§  Am.  Jour.  Vol.  XIV,  p.  10.    See  also  Vol.  IV,  p.  22. 


334  SALTS— SULPHATES. 

(/.)  Also  by  calcining  the  magnesian  limestones;  treating  them 
with  muriatic  acid  to  dissolve  the  lime,  and  then  with  sulphuric  acid, 
or  sulphate  of  iron,  to  form  the  sulphate  of  magnesia.* 

SULPHATE  OF  ALUMINA  AND  ALUM. 

Common  alum. 

1.  PREPARATION. — Always  prepared  in  the  large  way;  rarely 
by  the  chemist ,  unless  in  analysis. 

2.  PROPERTIES. 

(a.)  Its  properties  are  always  shown  by  the  alum  of  commerce, 
which  is  a  triple  salt,  and  not  mere  sulphate  of  alumina,  which  has 
characters  entirely  different. 

(b.)  Crystals  formed  from  a  hot  concentrated  solution,  filtered ; 
a  frame  of  sticks  or  some  hairs  or  strings  or  wires  are  often  suspended 
in  it,  for  the  crystals  to  adhere  to  ;  they  form  a  beautiful  group,  and 
are  handsomely  exhibited  in  a  bottle. 

(c.)  Aqueous  fusion  and  subsequent  desiccation  by  heat,  on  an  ignited 
iron  ;  the  product  was  formerly  called  alumen  ustum  ;  there  is  a  par- 
tial expulsion  of  the  acid — so  that  the  solution  of  the  desiccated  alum 
does  not  easily  redden  blue  vegetable  colors. f  By  a  very  violent 
heat,  most  of  the  acid  is  expelled.  The  solution  of  the  crystals  red- 
dens litmus  liquor  decidedly,  cabbage  liquor  slightly,  "  but  blue  tinc- 
tures, from  the  petals  of  plants,  are  generally  turned  by  it  green."f 

(«?.)  Air  has  generally  no  action — sometimes  produces  a  slight 
efflorescence. 

(e.)  Taste,  sweetish,  acid,  and  astringent;  rather  agreeable  to 
most  persons. — Specific  gravity  1.71. 

(/.)  Water  5 parts  at  60°  dissolves  1  of  the  salt;  at  212°  1  part 
of  water  dissolves  three  fourths  of  its  weight. 

Or-)  Pyrophorus. — Take  3  parts  of  alum  and  1  of  flour  or  brown 
sugar,  heat  the  mixture,  and  stir  it  constantly,  in  an  iron  pot  or  ladle, 
tiU  it  has  ceased  to  swell,  and  has  become  dry  ;  powder  the  mixture 
finely,  and  introduce  it  into  a  vial  coated  with  clay ;  set  this  in  a 
sand  heat,  and  continue  the  heat  till  gas  ceases  to  be  inflamed,  by 
bringing  a  lighted  paper  to  the  mouth ;  we  are  usually  directed  to  in- 
troduce a  small  tube,  through  a  perforated  cork,  into  the  vial's  mouth ; 
when  the  operation  is  over  this  may  be  removed  and  a  cork  substituted. 

(h.)  This  pyrophorus  fires  in  the  air  ;  more  vividly,  in  ajar  of 
oxygen  gas ;  it  fires  also  in  chlorine  and  nitric  oxide  gas. 


*  Id.  and  Ann.  de  China,  et  de  Phys.  T.  VI,  p.  86,  and  Gray's  Op.  Chem. 

t  It  is  suggested  that  the  effect  of  alum  on  blue  colors,  may  be  owing  to  a  feeble 
affinity  between  the  acid  and  the  earth,  and  of  course  to  an  attraction  between  the 
acid  and  the  coloring  matter,  rather  than  to  an  excess  of  acid. 

t  Quarterly  Jour.  XVIII,  396. 


SALTS— SULPHATES. 

The  foregoing  process  for  pyrophorus,  which  is  the  usual  one,  is  of 
rather  uncertain  success,  and  the  theoretical  reasoning  formerly  given 
respecting  it  being  imperfect,  I  do  not  repeat  it  here ;  but  proceed  to 
state  a  better  process,  furnished  me  by  Dr.  Hare,  and  one  which 
rarely  fails  to  succeed. 

Take  lampblack  3  parts,  calcined  alum  4$  pearl  ashes  8,  mix  them 
thoroughly,  and  heat  them  for  one  hour,  in  a  coated  iron  tube,  to  a 
bright  cherry  red,  or  full  red,  but  not  to  a  white  heat.  Black's  fur- 
nace, filled  with  charcoal  thoroughly  ignited,  the  flues  being  then 
shut,  and  when  the  fuel  is  half  burnt  down,  again  filled,  and  allow- 
ed to  burn  quietly  out,  with  the  flues  still  cloesd,  or  nearly  so,  will 
give  a  good  pyrophorus.  The  tube  must  not  be  opened  until  it  is 
cold,  and  then  very  cautiously.  The  pyrophorus  may  be  jarred  out, 
by  inclining  the  tube,  and  gently  striking  it  with  a  hammer.  If  good, 
it  fires  on  falling  out,  especially  if  the  air  is  damp,  or  if  breathed  upon ; 
caution  should  be  observed  lest  the  little  explosions  injure  the  eyes. 
If  a  ramrod  be  introduced  to  detach  the  pyrophorus,  the  operator 
should  be  on  his  guard,  as  a  violent  explosion  sometimes  happens, 
discharging  the  whole  contents  at  once,  with  a  loud  report.*  This 
pyrophorus  fires  brilliantly,  if  a  large  stream  of  oxygen  gas  be  direct- 
ed upon  it  from  a  gazometer,  or  if  it  be  poured  into  oxygen,  or 
chlorine  or  nitric  oxide  gas.  It  fires  also,  if  thrown  upon  water  or 
fuming  nitrous  acid .  There  can  be  little  doubt  that  sulphuret  of  po- 
tassium must  be  formed  in  this  process,  and  that  to  potassium,  in 
some  state  or  other,  the  principal  phenomena  must  be  attributed. 

(i.)  All  the,  alkalies  and  soluble  alkaline  earths  decompose  this  salt, 
and  if  ammonia  enter  into  its  constitution,  it  is  perceived  by  the  odorr 
when  either  of  the  other  alkaline  bodies  is  added  and  heat  applied, 
and  by  the  cloud  formed  with  the  fuming  acids. 

(/.)  Jill  the  alkalies  throw  down  the  alumina;  potassa  and  soda 
redissolve  it,  if  added  in  excess,  and  yield  it  up  again  if  detached  by 
an  acid. 

(k.)  Ammonia  precipitates  the  earth  without  redissolving  it,  or 
only  very  slightly,  and  heat  would  throw  down  even  this  little. 

(I.)  The  soluble  alkaline  earths  throw  down  a  mixed  precipitate, 
of  alumina  and  the  earths,  combined  with  the  sulphuric  acid. 

(m.)  Baryta  and  strontia,  are  proper  for  the  discovery  of  potassa; 
if  present,  it  would  remain  in  solution,  and  could  be  detected  by 
muriate  of  platinum. 

(n.)  The  carbonates  of  alkalies  decompose  this  salt,  with  a  slight 
effervescence  at  first,  and  throw  down  a  carbonated  earth. 

(0.)    Crystals  of  alum  are  usually  octahedral; 

*  See  Am.  Jour,  of  Science,  Vol.  X,  p.  366,  and  the  same  thing  has  often  occur- 
red to  me  since. 


336  SALTS— SULPHATES. 

(p.)  But  they  become  cubical,  by  letting  a  solution  of  common  alum 
stand  for  some  time  upon  either  alumina  or  potassa ;  still,  with  a  great 
excess  of  potassa,  alum  does  not  crystallize. 

(q.)  Saturate  alum,  with  alumina,  by  boiling  a  solution  of  common 
alum  upon  it ;  it  becomes  a  tasteless  insoluble  powder. 

(r.)  Digest  natural  clays  in  sulphuric  acid;  they  dissolve  only 
partially,  and  scarcely  saturate  the  acid ;  dissolve  newly  prepared 
alumina  (added  in  excess)  in  sulphuric  acid,  and  a  neutral  sulphate 
is  formed,  which  crystallizes  in  thin  flakes,  and  becomes  alum  by 
adding  potassa  or  its  sulphate. 

2.  COMPOSITION  AND  VARIETIES. 

(a.)  The  most  common  variety  of  alum  is  that  which  contains  po- 
tassa, but  there  has  been  considerable  diversity  in  the  statements 
made  of  its  constitution :  the  following  is  the  average  of  six  analyses.* 
Sulphuric  acid,  33.22  5  aluminous  earth,  1 1 .07 ;  potassa,  9.88  ;  water, 
45.92  =  100. 

(b.)  According  to  Mr.  R.  Phillips,  alum  consists  of  1  proportion  of 
bi-sulphate  of  potassa,  128;  2  of  sulphate  of  alumina,  (67  X2)  =134; 
25  of  water,  (9x25)  =225=487,f  its  equivalent  number. 

Dr.  Thomson  supposes  alum  to  be  composed  of  1  proportion  of 
sulphate  of  potassa,  88;  3  of  sulphate  of  alumina,{  (58x3)  174; 
25  of  water,  225=487. 

The  difference  between  these  two  views  is,  that  in  the  former  the 
equivalent  of  alumina  is  taken  at  27,  and  in  the  latter  at  18;  and 
adding  40  in  each  case  for  the  sulphuric  acid,  we  have  67  and  58 
for  the  equivalent  of  sulphate  of  alumina,  of  which  2  proportions  are 
taken  in  Mr.  Phillips'  statement,  and  2  in  that  of  Dr.  Thomson. 

(c.)  Alum  with  basis  of  ammonia,^  consists  of  1  proportion  of  sul- 
phate of  ammonia,  57 ;  3  of  sulphate  of  alumina,  58  X  3  =  174  ;  24  of 
water,  9  X24=216  ;  and  of  the  acid,  26.979  are  united  to  11.906  of 
the  earth,  and  9.063  are  united  to  3.898  of  ammonia. 

(d.)  Jllum  with  basis  ofsoda.\\ — Its  composition  is  stated  as  being 
water,  51.21;  acid,  32.14;  earth,  10.;  soda,  6.32:  or,  2  propor- 
tions of  sulphate  of  alumina,  1  of  bi-sulphate  of  soda,  28  of  water. 
A  native  soda  alum  is  found  in  the  isle  of  Milo,  Greece,  and  in 
South  Am  erica.  TT 

*  As  given  by  Dr.  Henry,  Vol.  I,  p.  632,  10th  ed. 

t  In  this  statement,  the  experimental  results  are  slightly  changed,  to  accommo- 
date them  to  definite  proportions,  and  the  equivalent  of  alumina  is  taken  at  27. 

t  The  equivalent  of  alumina  being  taken  at  18.  The  chemical  equivalent  of  alu- 
mina is  not  yet  ascertained  with  certainty,  but  Mr.  Murray  remarks,  (II.  182,)  that 
from  the  analysis  of  salts  and  minerals  containing  alumina,  it  is  more  probable  that 
18  is  the  true  number. 

§  According  to  Riffault,  Ann.  de  Chim.  et  de  Phys.  IX,  106. 

II  Quarterly  Jour.  VIII-  386,  and  XIII.  276.  I  have  prepared  a  lithia  alum,  in 
large  quantities,  from  the  Sterling  spodumene,  in  following  Berzelius'  process  for 
extracting  lithia.  It  is  deliquescent,  hut  in  other  respects  resembles  the  potassa 
alum,— J.  T.  IT  Am.  Jour.  Vol.  XVI.  p.  203. 


SALTS— SULPHITES.  337 

(e.)  Magnesia  also  appears  to  form  a  variety  of  alum,  but  it  has 
not  been  applied  to  use. 

(/.)  For  a  notice  of  a  neutral  sulphate  of  alumina,  and  for  one  of  a 
sub-sulphate  of  alumina  and  potassa,  &ic.  see  Henry,  Vol.  I,  p.  634, 
10th  ed.— Ann.  de  Chim.  et  de  Phys.  VI,  201  and  XVI,  355, 
and  Dr.  Thomson's  First  Principles,  I,  313. 

SULPHITES  OF  ALKALIES  AND  EARTHS. 

General  characters. 

1.  Taste  and  smell  like  that  of  burning  sulphur. 

2.  Heat  expels  sulphurous  acid  and  water,  and  finally  sulphur, 
which,  when  inflamed,  burns  violently,  and  a  sulphate  remains.* 

3.  Solution  slowly  absorbs  oxygen  from  the  air  and  becomes  sul- 
phate. 

4.  Chlorine  and  nitric  acids  convert  the  sulphites  into  sulphates ; 
and  nitric  acid  gives  out  red  fumes.     Sulphuric  and  muriatic  acids 
expel  the  sulphurous  acid  with  effervescence. 

5.  The  sulphites  are  not  precipitated  by  solution  of  baryta  or 
strontia,  or  by  any  of  their  salts. 

6.  They  are  formed  by  passing  a  stream  of  sulphurous  acid  gas 
through  the  base,  dissolved  or  suspended  in  water. 

7.  The  alkaline  sulphites  are  most  soluble  and  crystallizable. 

8.  A  neutral  sulphite,  when  its  acid  is  oxygenized,  always  forms  a 
neutral  sulphate. 

SULPHITE  OF  LIME. 

1 .  Besides  the  general  method,  already  mentioned,  this  salt  may 
be  formed  from  the  carbonate. 

2.  Insoluble  at  first,  but  is  dissolved  by  continuing  to  pass  sulphur- 
ous acid  through  it. 

3.  Crystallizes  in  six  sided  prisms,  acuminated  by  six  planes. 

4.  Requires  800  parts  of  water  for  solution,  unless  there  be  an 
excess  of  acid. 

5.  Proportions,  lime  28,  sulphurous  acid  32,  by  theory. — Brande. 

SULPHITE  OF  BARYTA. 

1.  It  may  be  formed  by  passing  sulphurous  acid  over  carbonate  of 
baryta. 

2.  A  white  powder,  little  soluble,  becomes  more  so  by  passing 
sulphurous  acid  gas  in  excess  through  the  powder. 

3.  Composition. — Baryta  78,  acid  40 ;  by  theory,  one  proportion 
of  each. 


Except  the  sulphate  of  ammonia,  which  is  entirely  exhaled 
43 


338  SALTS-SULPHITES. 

SULPHITE  OF  STRONTIA. 

This  salt  is  most  easily  formed,  by  mingling  an  alkaline  sulphite 
with  a  solution  of  the  earth  in  an  acid,  when  there  will  be  a  precipit- 
ate of  the  sulphite  of  strontia,  which  is  insoluble. 

SULPHITE  OF  MAGNESIA. 

1.  Formed  also  by  diffusing  the  carbonate  in  water,   and  passing 
sulphurous  acid  gas  through  it. 

2.  Insoluble  till  there  is  an  excess  of  the  acid ;  gives  crystals  which 
are  flattened  tetrahedra. 

3.  Requires  20  parts  of  cold  water  for  solution. 

4.  Taste  sweetish  and  earthy. 

SULPHITE  OF  ALUMINA. 

1.  A  white  soft  insoluble  powder. 

2.  Soluble  in  an  excess  of  acid. 

SULPHITE  OF  POTASSA. 

1.  Formed  with  ease,  from  a  saturated  solution  of  the  carbonate. 

2.  Crystals,  long  rhomboidal  plates  or  divergent  needles. 

3.  Soluble  in  water,  1  part  at  60°,  in  less  at  212°. 

4.  Composition,  43.5  acid,  54.5  potassa,  2  water;  (Thomson)  by 
theory,  1  potassa,  48;  1  acid,  32  =  80,  its  equivalent. 

5.  Slightly  effloresces  in  air,  and  becomes  sulphate;  decrepitates. 

6.  Decomposed  by  baryta  and  lime. 

SULPHITE  OF   SODA. 

1.  Crystals,  tetrahedral  prisms,  with  dihedral  summits. 

2.  Dissolves  in  4  parts  of  cold  water,  in  less  than  1  at. 2 12°. 

3.  Effloresces ;  suffers  aqueous  fusion,  and  is  decomposed  at  last 
by  heat. 

4.  Composition,  soda  1  proportion   32,  acid  32,  water  9=108; 
=  172  for  the  equivalent. 

5.  Potash  decomposes  it,  attracting  its  base. 

SULPHITE  OF  AMMONIA. 

1.  Crystals,  six  sided  prisms,  terminated  by  pyramids  with  the 
snme  number  of  sides,  or  rhomboidal  prisms  with  trihedral  summits. 

2.  Soluble  in  1  part  of  cold  water,  and  in  less  at  212°. 

3.  Deliquesces,  and  becomes  converted  into  a  dry  sulphate. 

4.  Fused  and  volatilized  by  heat. 

5.  Composition,  17  ammonia,   32  acid,  for  the  anhydrous  salt, 
giving  49  for  its  equivalent ;  and  when   crystallized,  2  equivalents 
of  the  salt, = 98 -f  1  of  water,  9=107  by  theory. — Brande. 


HYPO-SULPHUROUS  ACID.  339 

HYPO-SULPHUROUS    ACID.  HYPO-SULPHURIC  ACID. 

HYPO-SULPHITES.  HYPO-SULPHATES. 

Remarks. — In  the  present  advanced  state  of  chemistry,  the  most 
serious  inconvenience  encountered  by  the  student,  is  found  in  the  great 
extent  and  variety  of  details.  In  a  concise  elementary  work,  it  is  im- 
possible to  present  them  all,  and  there  seems  to  be  no  better  course 
than  to  omit,  or  to  notice  slightly  the  least  important,  and  to  enlarge 
upon  those  of  the  opposite  character,  giving  at  the  same  time,  sufficient 
references  to  original  sources  of  information. 

Were  it  not  that  it  is  desirable  to  preserve  the  chemical  history  of 
bodies  unbroken,  and  particularly  to  display  the  extent  and  precision 
of  definite  and  multiple  proportions,  I  should  hardly  have  thought  it 
best  to  say  any  thing  of  the  preceding  sulphites  or  of  the  acids  and 
their  compounds  which  stand  at  the  head  of  these  remarks. 

HYPO-SULPHUROUS  ACID. 

1.  Composition. — 1  proportion  of  oxygen,  8,  and  1  of  sulphur,  32 
=40,  for  its  equivalent. 

2.  Preparation. — Difficult  to  obtain  and  preserve  in  an  isolated 
state.     It  is  done, 

(a.)  By  decomposing  the  dilute  solution  of  hypo-sulphite  of  stron- 
tia,  by  dilute  sulphuric  acid ;  the  earth  is  precipitated  and  the  acid 
liberated. 

(5.)  By  digesting  sulphur  in  a  solution  of  any  sulphite,  when  an  ad- 
ditional proportion  of  sulphur  is  dissolved,  and  hypo-sulphurous  acid 
formed  ;  or  by  decomposing  hydro-sulphuret  of  lime*  or  strontia,  by  a 
stream  of  sulphurous  acid  gas,  when  there  is  an  exchange  of  one  pro- 
portion of  the  oxygen  of  the  sulphurous  acid  for  one  proportion  of 
the  sulphur  of  the  hydro-sulphuret,  water  being  formed,  and  thus  two 
proportions  of  sulphur  remain  in  union  with  one  of  oxygen. 

3.  Properties. — A  transparent,  colorless,  inodorous  acid  ;  decom- 
posed spontaneously,  sulphur  precipitated,  and  sulphurous  acid  re- 
mains. 

HYPO-SULPHITES,  OR  SULPHURETTED  SULPHITES. 

1.  Preparation. 

(a.)  The  hypo-sulphites  of  the  alkalies  and  alkaline  earths  are  best 
obtained  by  passing  a  stream  of  sulphurous  acid  gas  through  a  lixi- 
vium of  those  bodies  that  has  been  boiled  with  sulphur ;  the  sulphurous 
acid  is  converted  into  hypo-sulphurous,  and  the  excess  of  sulphur  pre- 
cipitated. 

(6.)  By  boiling  a  sulphite  with  sulphur. 

(c.)  By  double  decomposition  ;  an  alkaline  hypo-sulphite  being 
mixed  with  an  acid  solution  of  some  other  base. 

*Seep.  347. 


340  HYPO-SULPHURIC  ACID. 

2.  Properties. 

(a.)  Generally  soluble  in  water,  and  have  a  bitter  taste  ;  precipi- 
tate nitrate  of  silver  and  mercury  black,  in  the  form  of  sulphurets  of 
those  metals ;  salts  of  lead  and  baryta  are  thrown  down  as  white  in- 
soluble hypo-sulphites  of  those  bases. 

(6.)  Muriate  of  silver,  recently  precipitated,  is  dissolved  by  the 
hypo-sulphites,  and  especially  by  that  of  soda,  and  a  fluid  is  formed 
sweeter  than  honey,  and  entirely  void  of  metallic  taste.  The  hypo- 
sulphite of  ammonia  forms  with  muriate  of  silver,  a  white  salt  of  which 
1  grain  imparts  a  perceptible  sweetness  to  32,000  grains  of  water.* 

HYPO-SULPHURIC  ACID. 

1.  Discovery. — In  1819,  by  Welter  and  Gay-Lussac.f 

2.  Preparation. — Black  oxide  of  manganese  in  fine  powder,  is 
suspended  in  water,  and  a  stream  of  sulphurous  acid  gas  passed 
through ;  two  acids  are  formed  by  the  oxygen  of  the  manganese ; 
the  sulphuric  and  hypo-sulphuric,  and  both  unite  with  the  base,  form- 
ing sulphate  and  hypo-sulphate  of  manganese  ;  both  are  decomposed 
by  adding  solution  of  baryta  slightly  in  excess,  which  precipitates 
manganese  and  sulphate  of  baryta,  and  leaves  hypo-sulphate  of  baryta 
in  solution.     Carbonic  acid  gas  is  then  passed  through,  to  remove 
any  excess  of  baryta ;  the  solution  is  boiled  to  expel  the  carbonic 
acid,  and  by  evaporation,  hypo-sulphate  of  baryta  is  obtained  in  crys- 
tals.    To  a  solution  of  these  crystals,  sufficient  sulphuric  acid  is  cau- 
tiously added  to  saturate  the  baryta,  which  is  precipitated  in  the  form 
of  sulphate,  and  the  hypo-sulphurous  acid  remains  in  solution. 

3.  Properties. 

(a.)  A  colorless,  inodorous  acid,  changes  the  test  fluids ;  concen- 
trated by  heat,  or  under  the  receiver  of  the  air  pump,  its  sp.  gr.  is 
1.347,  but  if  attempted  to  be  carried  farther,  especially  by  heat,  it  is 
decomposed  and  converted  into  sulphurous  and  sulphuric  acids. 

(6.)  Suffers  no  change  from  the  air  or  from  nitric  acid ;  it  dis- 
solves zinc  like  the  stronger  acids,  and  forms  hypo-sulphate  of  zinc, 
while  hydrogen  gas  is  evolved. 

(c.)  It  forms  soluble  salts  with  baryta,  strontia,  lime,  lead,  and 
silver,  which  completely  distinguishes  it  from  sulphuric  acid. 

4.  Composition. — Ascertained  by  decomposing  the  hypo-sulphate 
of  baryta  by  heat,  and  the  proportion  of  sulphur  appears  to  be  1=32, 
and  of  oxygen,  5=40=72,  for  its  equivalent. 

HYPO-SULPHATES. 

1.  Preparation. — Formed  by  direct  combination  with  bases. 


*  For  numerous  additional  particulars,  see  Ann.  de  China.  Vol.  LXXXV  ;  Edin. 
Philos.  Jour.  Jan.  1819,  Vol.  1, 8,  and  396,  and  Ure's  Diet.  2d  Ed.  p.  97. 
t  Ann.  de  Chim.  et  de  Phys.  Vol.  X. 


SULPHURETTED  HYDROGEN.  341 

2.  Properties. 

(a.)  All  soluble;  decomposed  by  a  moderate  heat,  sulphurous 
acid  gas  being  exhaled  and  sulphates  remaining. 

(b.)  Strong  sulphuric  acid  decomposes  the  acid  of  the  hypo-sul- 
phates, at  the  instant  when  it  is  decomposing  the  salts  which  contain 
it ;  a  weak  acid,  applied  cold,  separates  the  hypo-sulphuric  acid  with- 
out decomposition. 

(c.)  Not  changed  by  the  air,  or  only  slightly  absorb  oxygen. 
The  hypo-sulphate  of  baryta  crystallizes  in  square  prisms  of  pecul- 
iar brilliancy ;  that  of  potassa  in  a  cylindroidal  form ;  that  of  lime  in 
hexagonal,  and  that  of  strontia  in  very  small  hexahedral  laminae. 
Composition  of  the  acids  of  sulphur. 

Sulphur.    Oxygen. 

Hypo-sulphurous  acid,  -     16  -f     8     1  and  1  proper* 

Sulphurous  acid,    -  16  -f   16     1  and  2      " 

Sulphuric  acid,  -      16  +  24     1  and  3      " 

Hypo-sulphuric  acid,       -  32  +  40     2  and  5      " 

Thus  these  compounds  beautifully  illustrate  the  laws  of  definite 
and  multiple  proportions. 

COMPOUNDS  FORMED  BETWEEN  SULPHUR,  HYDROGEN,  AND  THE  AL- 
KALIES AND  EARTHS. 
SULPHURETTED  HYDROGEN. 

1.  NOMENCLATURE. — The   termination  uret  is   appropriated   to 
combinations  of  simple  combustible,  non-metallic*  bodies,  with  each 
other  and  with  the  metals,  alkalies,  and  earths.     Thus,  in  the  case 
of  sulphur  and  phosphorus,  we  have  sulphuret  of  phosphorus,  or 
phosphuret  of  sulphur,  sulphuret  or  phosphuret  of  lime,  and  of  calci- 
um, of  potassa,  and  of  potassium,  of  iron,  &tc.     To  denote  different 
proportions  of  the  principles,  terms  are  derived  either  from  some 
sensible  property,  usually  the  color  ;  e.  g.  we  have  a  black  and  red 
sulphuret  of  mercury,  yellow  and  red  sulphuret  of  arsenic,  &tc. ;  or 
it  is  now  more  usual  to  prefix  the  same  terms  that  are  applied  to  the 
oxides,  as  proto-sulphuret,  deuto-sulphuret,  &c.  implying  one  or  two- 
proportions  of  sulphur,  &c. 

Where  the  compound  is  gaseous,  it  is  usual  to  add  ted  to  the  ter- 
mination uret  ;  as  sulphuretted  hydrogen  and  phosphuretted  hydro- 
gen, instead  of  sulphuret  and  phosphuret  of  hydrogen. 

2.  HISTORY. — Known  to  Rouelle,  but  first  investigated  by  Scheele, 
A.  D.  1777  ;  afterwards  by  many  distinguished  chemists. 

3.  PROCESSES. 

(a.)  By  heating  sulphur  in  hydrogen  gas,  by  the  solar  rays ;  or 
by  subliming  sulphur,  repeatedly,  in  hydrogen  gas ;  or,  by  passing 
this  gas  over  sulphur  heated  in  a  porcelain  or  coated  glass  tube. 

*  The  compounds  of  metallic  bodies  with  each  other  are  called  alloys. 


342  SULPHURETTED  HYDROGEN. 

(b.)  Better  by  the  aid  of  sulphuret  of  iron,  to  prepare  which,  min- 
gle flowers  of  sulphur  and  iron  filings,  equal  parts  ;*  heat  them  in  an 
iron  pot  or  skillet,  under  a  chimney,  not  merely  till  the  sulphur 
melts,  which  happens  almost  immediately,  but  until  an  intimate 
chemical  union  is  indicated,  by  incandescence  pervading  the  entire 
mass  ;  it  begins  with  a  little  luminous  spot  or  spots,  and  gradually  ex- 
tends through  the  whole,  while  the  vessel  containing  the  materials  is 
perhaps  not  even  red ;  at  this  moment,  the  boiling  and  combustion  of 
sulphur  cease,  for  it  is  now  detained  by  its  affinity  for  the  iron. 
The  sulphuret  being  pulverized,  is  fit  for  use,  and  will  not  disappoint 
the  experimenter.f 

(c.)  To  one  part  of  the  sulphuret  of  iron  thus  made,  add  2  of  mu- 
riatic acid,  with  4  of  warm  water,  and  when  the  gas  begins  to  come 
languidly,  a  little  heat  may  be  applied. 

(d.)  Powdered  sulphuret  of  antimony,  with  5  or  6  times  its  weight 
of  muriatic  acid,  (sp.  gr.  about  1.160,)  apply  the  heat  of  a  lamp  ; 
this  process,  although  strongly  recommended,  has  not  succeeded  well 
with  me. 

(e.)  Add  diluted  sulphuric  or  muriatic  acid  to  almost  any  alkaline 
sulphuret,  preferably  of  potassa,  but  the  gas  comes  too  rapidly  to  be 
easily  managed  ;  process  (c.)  is  the  best. 

4.  PROPERTIES. 

(a.)  Sp.gr.  1.18,  air  being  1;  100  cub.  inch,  weigh  nearly  36 
grains.  { 

(b.)  Smell  very  offensive,  like  that  of  rotten  eggs,  or  of  sulphureous 
mineral  waters. 

(c.)  When  kindled  in  contact  with  air,  it  burns  quietly,  with  a 
bluish  white  flame,  and  deposits  sulphur  on  the  glass  vessel. 

Sd.)  Mixed  with  common  air,  it  burns  more  rapidly. 
e.)   With  oxygen,  three  measures  to  two  of  this  gas,  it  detonates, 
producing  water  and  sulphurous  acid. 

(jf.)  Water  absorbs  its  own  volume  or,  if  the  gas  be  pure,  even  two 
or  three  times  its  volume,  and  then  resembles  exactly,  the  native 
sulphureous  waters. 


*  Or  sulphur  1  part,  iron  2. 

t  The  mere  melting  of  iron  filings  and  sulphur,  and  still  more  the  mere  mingling 
of  them  will  not  answer ;  for,  when  the  acid  is  added,  the  gas  produced  will  be 
merely  a  mixture  of  sulphuretted  hydrogen,  and  common  hydrogen  gas.  The  pro- 
cess by  rubbing  roll  sulphur  upon  a  bar  of  iron  heated  to  whiteness,  till  liquid  drops 
fall,  gives  also  a  true  sulphuret  which  will  afford  the  gas,  but  the  manipulation  is 
more  troublesome,  and  the  product  of  sulphuret  of  iron  is  small. 

The  following  process  was  communicated. — Heating  the  native  yellow  pyrites,  in 
a  close  crucible,  till  1  proportion  of  sulphur  is  expelled  ;  and  a  fine  proto-sulphuret 
will  be  left.  J.  T. 

t  35.89,  according  to  Dr.  Thomson.  Different  authors  have  stated  its  sp.  gr.  dif- 
ferently. 


• 


SULPHURETTED  HYDROGEN.  343 

(g.)  This  fluid  tarnishes  metallic  solutions,  and  bright  metals;  e.  g. 
silver,  mercury  ;  also,  white  paint,  acetate  of  lead,  muriate  of  bismuth, 
nitrate  of  silver,  &ic. 

(A.)  Write  with  a  solution  of  silver  or  lead  on  cards,  and  expose 
them  to  this  gas ;  Dr.  Henry  found  that  ¥T£ F7F  part  of  this  gas,  mix- 
ed with  common  air,  or  hydrogen,  or  carburetted  hydrogen,  pro- 
duced a  sensible  discoloration  of  white  lead,  or  of  oxide  of  bismuth, 
mixed  with  water  and  spread  upon  a  card. 

(i.)  Moisten  the  entire  surface  of  cards  with  the  solution,  and  ex- 
pose them  as  above,  when  they  will  be  entirely  tarnished. 

(j.)  Aqueous  solution  reddens  infusion  of  violets  or  litmus  liquor 
or  paper,  and  in  this  respect  resembles  the  acids. 

(k.)  Sulphuretted  hydrogen  being  mixed  with  sulphurous  acid, 
either  liquid  or  gaseous,  sulphur  is  deposited  by  mutual  decomposi- 
tion ;  if  3  volumes  of  sulphuretted  hydrogen  be  mixed  with  2  of  sul- 
phurous acid  gas,  both  being  dry,  they  are  entirely  condensed  into 
an  orange  yellow  substance,  having  acid  properties,  and  consisting, 
according  to  Dr.  Thomson,  of  5  proportions  of  sulphur,  4  of  oxygen, 
and  3  of  hydrogen.* 

(/.)  Liquid  sulphuretted  hydrogen  deposits  sulphur,  by  exposure 
to  air,  or  even  in  a  bottle,  and  in  the  channels  where  the  sulphureous 
mineral  waters  run.  Fuming  nitrous  acid  precipitates  the  sulphur, 
but  the  colorless  acid  does  not. 

(m.)  Fuming  nitrous  acid,  being  poured  into  a  wide  mouthed  re- 
ceiver, filled  with  sulphuretted  hydrogen,  decomposition  happens,  and 
a  beautiful  flame  spreads  through  the  interior  of  the  vessel.f 

(n.}    Chlorine  decomposes  this  gas  and  precipitates  the  sulphur. 

(o.)  Very  hostile  to  life ;  if  pure,  kills  almost  instantly  ;  or 
even  if  mingled  with  a  large  proportion  of  air,  it  is  very  noxious. 
Air  containing  only  T1V  o-  killed  a  bird,  jfa  a  dog,  and  ^  j  -$  a  horse.  J 
A  young  rabbit,  whose  head  was  in  the  pure  air,  and  its  body  en- 
closed in  a  bladder  filled  with  sulphuretted  hydrogen,  died  in  15  or 
20  minutes ;  old  rabbits  lived  longer.  It  is  fatal,  therefore,  when  ap- 
plied to  the  surface  of  the  body. 

(p.)  Sulphuretted  hydrogen  precipitates  all  the  metals,  except 
iron,  nickel,  cobalt,  manganese,  titanium,  and  molybdena. 

(q.)  Electricity  and  galvanism  throw  down  sulphur,  and  an  equal 
volume  of  hydrogen  gas  remains ;  sulphuretted  hydrogen  is  partially 


*  Ann.  Phil.  Vol.  XII,  p.  441. 

A  similar  decomposition  is  supposed  by  Prof.  Daubcny  to  be  the  principal  source 
of  volcanic  sulphur.     See  his  lectures  on  Volcanos,  Am.  Jour.  Vol.  XIII,  No.  2. 
t  Ann.  of  Phil.  Vol.  VIII,  p.  226,  and  Henry,  Vol.  I,  p.  449,  10th  Ed. 
;  Thenard,  Vol.  I,  723. 


344  BI-SULPHURETTED  HYDROGEN. 

decomposed,  by  being  passed  through  an  ignited  porcelain  tube,  or 
over  ignited  charcoal. — Thenard. 

(r.)  Alkalies  absorb  it  readily,  and  thus  it  is  easily  separated  from 
common  hydrogen. 

(s.)  Potassium  and  sodium,  heated  in  this  gas  burn  brilliantly ; 
i.  e.  much  heat  and  light  are  evolved,  and  a  sulphuret  of  the  metal 
is  formed,  while  as  much  hydrogen  gas  is  produced  as  the  metal 
would  have  liberated  from  water.  Diluted  muriatic  acid  produces 
from  the  sulphuret  the  original  quantity  of  sulphuretted  hydrogen  gas. 

5.  COMPOSITION. — According  to  Dr.  Thomson,  it  is  composed  of 
1  volume  of  the  vapor  of  sulphur  =1  proportion  1.111,  +1  vol.  of 
hydrogen  gas,  0.069 ;  these  numbers  being  almost  exactly  in  the 
ratio  of  1  :    16,  give  the  equivalent  weight  of  sulphur  very  nearly 
the  same  as  that  deduced  from  the  composition  of  sulphuric  acid.* 

6.  LIQUEFACTION  OF  SULPHURETTED  HYDROGEN. 

(a.)  Mr.  Faraday,  by  disengaging  this  gas  in  a  recurved  tube, 
sealed,  before  the  materials  were  brought  into  contact,  the  end  oppo- 
site to  that  in  which  they  were  contained  being  kept  cold  by  a  freez- 
ing mixture,  succeeded  in  condensing  it  into  a  liquid. 

(b.)  It  was  limpid,  colorless,  and  more  fluid  than  ether ;  equally 
fluid  at  0  as  at  45°  Fahr.  and  its  refractive  power  greater  than  that 
of  water. 

(c.)  The  tube  being  opened  under  water,  the  fluid  rushed  instant- 
ly into  gas,  which  was  sulphuretted  hydrogen.  The  pressure  of  its 
vapor,  at  50°  of  Fahr.f  was  equal  to  seventeen  atmospheres,  or  255 
Ib.  to  the  square  inch. 

Remarks. — Sulphuretted  hydrogen  gas  exists  abundantly  in  the 
sewers  and  privies  of  great  cities.  I  have  observed,  in  London,  that 
a  sudden  and  heavy  rain  would  force  it  out  in  great  quantities,  taint- 
ing the  atmosphere,  and  tarnished  white  lead  paint.  In  great  cities, 
especially  in  Paris,  it  is  often  fatal  to  those  who  clear  away  the  filth 
of  the  sewers :  the  best  antidote  and  remedy  is  chlorine,  especially 
in  the  form  of  chloride  of  lime. 

BI-SULPHURETTED  HYDROGEN. 

1.  DISCOVERY. — By  Scheele  originally,  and  afterwards  examined 
by  Berthollet.  J 

2.  PREPARATION. — Boil  flowers  of  sulphur  with  liquid  potassa ; 
pour  this  reddish  brown  solution,  by  little  and  little,  into  muriatic  acid ; 
very  little  sulphuretted  hydrogen  escapes,  and  a  part  of  it  combines 
with  more  sulphur,  and  precipitates,  of  an  oily  appearance ;  or,  fill 
one  third  of  a  vial  with  muriatic  acid,  of  the  sp.  gr.  1.07,  and  pour 

*  Henry,  Vol.  I.  p.  446,  10th  Ed.  f  Phil.  Trans.  1823,  p.  192. 

*  Ann.  de  Chim.  XXV,  and  Phil.  Trans. 


HYDRO-SULPHURETS.  345 

in  an  equal  bulk  of  the  above  named  compound  of  sulphur  and  al- 
kali ;  the  vial  being  corked  and  shaken,  the  peculiar  fluid  gradually 
subsides  to  the  bottom,  in  the  form  of  "  a  brown,  viscid,  semi-fluid 
mass." — Henry.  The  hydrogenized  sulphuret  of  lime  is  also  used, 
in  the  same  manner,  for  obtaining  this  compound. 

3.  PROPERTIES. 

(a.)  Odor  like  that  of  putrid  eggs ;  heavier  than  water ;  burns 
with  the  smell  of  sulphurous  acid. 

(5.)  A  gentle  heat  causes  sulphuretted  hydrogen  to  exhale,  and 
sulphur  only  is  left. 

(c.)  It  unites  with  alkalies  and  earths,  and  produces  the  sulphu- 
retted hydro-sulphurets,  or  hydroguretted  sulphurets. 

(d.)  If  kept  in  a  vial,  floating  on  water,  it  exhales  sulphuretted  hy- 
drogen, whenever  the  stopper  is  withdrawn. 

(e.)  If  placed  on  the  tongue,  it  gives  a  pungent  bitter  taste,  exhales 
sulphuretted  hydrogen,  and  leaves  sulphur  in  the  mouth. 

4.  COMPOSITION. — According  to  Mr.  Dalton,  2  proportions  of  sul- 
phur =32-f-l  of  hydrogen  =33.     In  centesimal  proportions,*  it  con- 
sists of  sulphur  96.75,  hydrogen  3.25  =  100.     Its  combinations  with 
alkalies  will  presently  be  considered. 

HYDRO-SULPHURETS. f 
COMPOUNDS  OF  SULPHURETTED  HYDROGEN  AND  BASES. 

Introductory  Remarks. 

It  has  been  already  observed,  that  sulphuretted  hydrogen  performs 
the  functions  of  an  acid.  It  is  not  sour  to  the  taste,  but  it  reddens 
the  infusion  of  vegetable  blue  colors,  or  at  least  that  of  litmus  or 
radishes ;  its  most  important  character,  as  an  acid,  is,  that  it  com- 
bines with  the  alkalies  and  alkaline  earths,  neutralizing  their  alkaline 
properties,  and  forming  crystallizable  compounds,  analogous  to  the 
salts.  Some  have  therefore  enrolled  sulphuretted  hydrogen  among 
the  acids,  but,  in  a  free  state,  except  a  feeble  effect  upon  some  of  the 
blue  test  colors,  its  properties  are  so  different  from  those  of  acids, 
that  I  prefer  to  consider  it  as  merely  a  compound  combustible  gas, 
adding  a  notice  of  those  properties  that  assimilate  it  to  acids. { 

1.  PREPARATION  of  hydro  sulphurets. — Formed,  by  passing  sul- 
phuretted hydrogen  gas  through  the  base,  suspended  or  dissolved  in 
water,  in  Woulfe's  or  other  convenient  apparatus. 


*  Henry,  Vol.  I,  p.  447. 

t  Called  .by  some  authors  hydro-sulphates,  but  it  would  seem,  unhappily;  as  the 
learner  is  in  danger  of  confounding  them  with  the  sulphates:  the  old  name  appears 
to  be  unexceptionable.  See  Dr.  Turner's  Chemistry,  2d  ed.  p.  603. 

\  It  has  been  called  the  hydro-thionic,  and  the  hydro-sulphuric  acid ;  neither 
name  has  obtained  much  currency,  and  the  latter  confounds  this  body  with  the  com- 
mon sulphuric  acid. 

44 


346  HYDRO-SULPHURETS. 

2.  GENERAL  PROPERTIES. 

(a.)  Soluble  in  water,  recent  solution  colorless,  by  exposure  to  the 
air  become  greenish  or  yellowish,  and  deposit  sulphur  on  the  sides 
of  the  vessel. 

(b.)  If  the  bottle  in  which  they  are  kept  contains  lead,  it  is  redu- 
ced, and  coats  the  interior  with  a  metallic  lining,  probably  a  sulphuret. 

(c.)  By  long  exposure  to  the  air,  and  even  by  long  keeping,  they 
pass  to  the  state  of  sulphites,  and  ultimately  to  that  of  sulphates,  which 
are  sometimes  precipitated,  and  sometimes  remain,  in  part  or  in  whole, 
in  solution. 

(d.)  Acids  liberate  sulphuretted  hydrogen,  but  do  not  precipitate 
sulphur  ; 

(e.)  Except*  the  nitric  acid,  which  combines  with  the  hydrogen 
to  form  water,  and  thus  liberate  sulphur ; 

(f.)  Except  also  when  the  hydro-sulphurets  have  been  partially 
decomposed  by  careless  keeping,  when  they  throw  down  sulphur. 

(g.)  Precipitate  all  metallic  solutions,  and  also  alumina  and  zir- 
conia,  but  no  other  earths. 

(A.)  Generally  crystallizable. 

(t.)  Take  up  an  additional  dose  of  sulphur,  by  digestion,  upon  it, 
but  do  not  suffer  it  to  be  again  precipitated  by  a  stream  of  sulphuret- 
ted hydrogen. 

(/.)  After  exposure,  for  some  time,  to  the  air,  exhale  sulphurous 
acid  gas  along  with  sulphuretted  hydrogen,  and  precipitate  sulphur. 

(k.)  Absorb  oxygen,  and  therefore  used  in  eudiometry. 

(I.)  If  there  is  no  more  sulphuretted  hydrogen  than  is  necessary  to 
saturate  the  base,  they  are  inodorous ;  but  they  usually  have  the  odor 
of  sulphuretted  hydrogen,  because  it  not  only  saturates  the  base,  but 
combines  with  the  water  of  the  solution,  which  after  the  superfluous 
gas  is  expelled,  by  heat,  will  no  longer  have  any  odor. 

(m.)  The  hydro-sulphurets  are  decomposed  by  heat,  and  the  base 
remains ;  ammonia  excepted,  which  is  exhaled. 

(w.)  It  is  said  that  sulphuretted  hydrogen  combines  with  alkalies, 
in  a  double  proportion,  forming  bi-hydro-sulphurets. 

HYDRO-SULPHURET  OF  POTASS  A. 

1.  Crystallizes  in  large  transparent  crystals,  similar  to  those  of  sul- 
phate of  soda  ;   four  sided  prisms  acuminated  by  four  planes,  or  six 
sided  prisms  with  six  planes,  at  the  ends. 

2.  Taste  alkaline   and  bitter,  inodorous  when  dry,   but  becomes 
odorant  by  moisture ;  is  deliquescent. 

3.  Forms  a  syrupy  liquor,  which  imparts  a  green  color  to  bodies 
in  contact  with  it. 

4.  Dissolves,  not  only  in  water  but  in  alcohol,  producing  cold. 

*  Chlorine  produces  the  same  effect  by  seizing  the  hydrogen. 


HYDRO-SULPHURETS.  347 

HYDRO-SULPHURET  OF  SODA. 

Crystals  formed  with  more  difficulty  than  the  preceding ;  trans- 
parent, quadrilateral  prisms,  acuminated  by  four  planes,  bearing  a 
close  resemblance  to  the  hydro-sulphuret  of  potassa.* 

HYDRO-SULPHURET    OF    AMMONIA. 

1 .  The  two  gases  mixed  over  mercury,  or  in  a  bottle,  or  other- 
wise, combine ;  in  equal  volumes,  they  are  almost  completely  con- 
densed into  an  odorous  cloud,  which  forms  a  soft  white  crystalline 
deposit  on  the  inside  of  the  vessel,  and  if  it  is  kept  cold  by  ice,  acic- 
ular  crystals  will  be  formed. 

2.  The  liquid  solution  is  easily  formed,  but  does  not  crystallize. 

3.  It  is  an  excellent  test,  in  examining  metallic  solutions. 

4.  Admitted  into  the  Pharmacopaeia,  as  a  depressing  and  nausea- 
ting remedy,  in  cases  of  too  great  action — introduced  by  Dr.  Rollo, 
and  used  chiefly  in  diabetes  ;f  dose,  5  or  six  drops,  three  or  four 
times  a  day,  gradually  increased,  and  mitigated,  when  nausea  and 
giddiness  supervene. 

HYDRO-SULPHURET   OF  LIME. 

1 .  Formed,  by  passing  the  gas,  either  through  lime  water,  or  milk 
of  lime. 

2.  It  is  formed  when  sulphur  is  boiled  with  lime  and  water ;  but 
there  is  also  another  product  soon  to  be  described. 

3.  I  have  often  seen  distinct  prisms  formed  in  the  solution  made 
by  boiling  lime  and  sulphur  to  saturation  in  water ;  I  am  not  aware 
that  they  have  been  examined  ;  if  not  hydro-sulphuret,  may  they  not 
be  hypo-sulphite  of  lime  ? 

HYDRO-SULPHURET  OF  BARYTA. 

1 .  Formed,  as  mentioned  in  the  general  characters  ;  but  by  far  the 
best  method  is  to  obtain  it  from  the  decomposed  sulphate,  by  char- 
coal, as  described  under  sulphate  of  baryta,  and  soon  to  be  mention- 
ed again,  with  particular  reference  to  this  subject. 

2.  It  crystallizes,  confusedly,  in  brilliant  plates,  which  must  be 
dried  between  folds  of  blotting  paper,  and  if  immediately  dissolved 
in  distilled  water,  they  form  a  colorless  solution. 


*  It  was  formerly  said  to  be  distinguished,  by  not  forming  alum  when  added  to 
sulphate  of  alumina,  which  the  other  salt  would  do,  but  this  distinction  was  indica- 
ted, probably,  before  it  was  known  that  there  is  a  triple  soda^alurn. 

t  The  physician  can  prepare  this  remedy  by  extricating  the  gas,  under  a  chim- 
ney, in  the  manner  already  described  under  sulphuretted  hydrogen,  and  passing  it 
from  an  oil  flask,  or  bottle,  through  the  aqua  ammonia?  of  the  shops,  contained  in  a 
vial  immersed  in  cold  water,  or  better,  surrounded  by  ice.  This  remedy  has  still 
considerable  reputation,  and  conjoined  with  a  diet  of  animal  muscle,  is  thought  to 
have  produced  the  most  salutary  results.  I  have  repeatedly  prepared  it  for  phy- 
sicians, and  have  always  heard  a  favorable  report  of  its  effects,  if  conjoined  with  a 
rigorous  diet. 


348  SULPHURETTED  HYDRO-SULPHURETS. 

HYDRO-SULPHURET    OF    STRONTIA. 

In  every  respect  as  the  last,  only  the  decomposition  of  the  sul- 
phate is  not  so  striking. 

HYDRO-SULPHURET    OF    MAGNESIA. 

1.  Formed  by  passing  the  gas  through  the  magnesia  suspended  in 
water. 

2.  It  is  a  feeble  and  imperfectly  characterized  compound. 

SULPHURETTED    HYDRO-SULPHURETS. * 

General  Characters. 

1.  Formed,  by  boiling  flowers  of  sulphur  with  the  base,  dissolved 
or  suspended  in  water. 

1 .  Caustic  heavy  fluids,  of  a  greenish  yellow,  or  brownish  color. 

2.  Stain  the  cuticle  black,  have  an  acrid  taste,  and   an  offensive 
smell. 

3.  Deposit  sulphur  when  kept  in  close  vessels,  and  become  more 
transparent,  and  lighter  colored. 

4.  Absorb  oxygen  gas,  and  therefore  used  in  eudiometry. 

5.  Sulphuric  and  muriatic  acids  throw  down  sulphur,  and  evolve 
sulphuretted  hydrogen. 

6.  Exposed  to  the  air  they  are  slowly  changed  into  sulphates. 

7.  Have  a  soapy  feel. 

8.  Sulphuretted  hydrogen,  passed  through  them,  precipitates  the 
excess  of  sulphur,  and  converts  them  into  hydro-sulphurets. 

9.  Sulphuretted  hydro-sulphurets,  are  formed  also,  by  digesting 
a  hydro-sulphuret  upon  sulphur,  but  they  do  not  throw  down  sulphur 
when  sulphuretted  hydrogen  is  passed  through  them.f 

SULPHURETTED  HYDRO-SULPHURET  OF  POTASSA. 

1.  Boil  sulphur,  1   part,  with  3  of  the  solution  of  caustic  potash, 
of  the  common  strength.  J 

2.  Or,  decompose  the  sulphate  of  potassa,  by  heating  it  red  hot 
along  with  J-  of  charcoal,  in  a  crucible  :  dissolve  every  thing  soluble 
in  hot  water,  and  filter  ;  the  theory  of  these  facts  will  be  given  farther 
on. 


*  Called  also  hydrogenized,  hydroguretted,  and  hydrogenated  sulphurets,  but  the 
name  in  the  text  is  preferred,  because  it  expresses  correctly  the  composition  of  these 
bodies. 

t  Aikin,  Vol.  2.  p.  364. 

t  Pearl  ashes,  water,  and  sulphur  boiled  together,  produce  hydrogenized  sulphu- 
ret  of  potassa  of  a  very  good  quality,  so  that  it  is  not  necessary  to  use  caustic  potash  ; 
probably  sal  soda  would  also  answer  instead  of  caustic  soda. 


SULPHURETTED  HYDRO-SULPHURETS,  349 

3.  The  color  varies  in  intensity  according  to  the  degree  of  con- 
centration. 

4.  The  principal  use  made  of  this  preparation  is  in  eudiometry  ; 
but  the  compound  with  lime  is  most  used,  which  see. 

SULPHURETTED    HYDRO-SULPHURET  OF  SODA. 

1 .  It  is  almost  perfectly  identical  with  the  last. 

2.  The  sulphate  may  be  decomposed  by  charcoal  in  the  same 
manner,  but  the  appearances  are  less  striking. 

SULPHURETTED   HYDRO-SULPHURET  OF  AMMONIA. 

1.  If  liquid  ammonia  be  digested  upon  sulphur,  the  action  is  fee- 
ble and  not  much  sulphur  is  dissolved. 

2.  But  ammonia  in  its  nascent  state,  dissolves  sulphur  readily. 

3.  A  preparation  of  this  kind  was  formerly  called  Boyle's  fuming 
liquor  ;  3*  parts  slacked  lime,  1  muriate  of  ammonia,   1   flowers  of 
sulphur,  and  half  a  part  of  water,  are  mingled  and  a  gentle  heat  ap- 
plied ;  the  first  drops  are  watery,  and  as  they  become  deeper  colored, 
the  heat  is  raised  till  the  bottom  of  the  retort  becomes  slightly  red. 

4.  White  fumes  are  abundantly  extricated  in  the  more  early  stages 
of  the  operation,  and  must  have  vent  from  the  receiver. 

5.  The  fumes  may  be  all  collected  in  a  Woulfe's  apparatus;  they 
are  more  abundant  and  incoercible  in  proportion  as  less  water  is 
added. 

6.  The  liquor  fumes,  as  soon  as  the  stopper  is  withdrawn  from  the 
bottle  in  which  it  is  kept. 

7.  The  fuming  is  owing  to  the  ammonia  in  excess,  meeting  with 
sulphuretted  hydrogen,f  for  when  the  fuming  liquor  is  digested  on  sul- 
phur, the  ammonia  becomes  saturated  and  the  fuming  ceases. 

SULPHURETTED   HYDRO-SULPHURET  OF   LIME. 

1.  Boil  slacked  lime  with  JJ  sulphur  and  10  parts  of  water,  for 
half  an  hour  or  an  hour,  and  shake  frequently  during  the  boiling. 

2.  The  fluid  is  of  a  fine  orange  yellow,  and  deposits  crystals  one 
cooling. 

3.  Decomposition  of  the  sulphate  by  charcoal  and  heat,  succeeds 
but  imperfectly. 

4.  For  the  rest,  see  general  properties. 

5.  This  preparation  and  the  parallel  one  of  potassa  are  much  used 
in  eudiometry,  and  this  is  rather  preferred,  because  it  affords  the 
most  concentrated  solution. 


*  1,  Ure. 

\  Proceeding,  doubtless,  from  the  decomposition  of  water,  by  the  compound  of  am- 
monia and  sulphur. 

t  Equal  weights  of  lime  and  sulphur. — Murray,  This  is  much  more  sulphur 
than  is  needed. 


350        SULPHURETTED  HYDRO  AND  LIQUID  SULPHURETS. 


EUDIOMETER  OF  DR.   HOPE. 

"  This  eudiometer  consists  of  a  graduated  glass 
tube,  sealed  at  one  end,  and  at  the  other  fitted, 
by  grinding,  into  the  mouth  of  a  tubulated  glass 
bottle,  so  as  to  be  air  tight.  Manipulation,  with 
this  instrument,  is  very  simple.  The  tube  is 
filled  with  gas,  the  bottle  with  the  liquid  which 
is  to  act  upon  the  gas.  The  tube  being,  under 
these  circumstances,  inserted  into  the  mouth  of 
the  bottle,  by  inverting  both,  the  contained  gas 
is  made  to  pass  into  the  bottle.  Agitation  is 
next  to  be  resorted  to,  and  time  allowed  for 
the  absorption  to  be  completed.  In  the  interim, 
the  tubulure  is  to  be  occasionally  opened  under 
water,  by  removing  a  ground  stopple  with  which 
it  is  furnished.  The  gas  absorbed,  is  conse- 
quently replaced  by  water. 

"  Finally,  the  stopple  must  be  removed,  the 
tube  being  previously  depressed  into  water,  till 
this  liquid  is  as  high  on  the  outside  as  within. 
The  graduation  being  at  the  same  time  inspected, 
the  deficit  produced  by  the  absorption  of  oxygen,  is  thus  ascertain- 
ed.''—!^. Hare. 

SULPHURETTED    HYDRO-SULPHURET   OF  BARYTA. 

1 .  This  compound  is  formed  either  by  boiling  pure  baryta  (4  parts.) 
in  powder,  or  in  crystals,  with  water  upon  sulphur,  1  part,  or  by  de- 
composing the  sulphate  of  baryta  by  igniting  it  along  with  one   sixth 
charcoal  powder  for  half  an  hour  ;  then  dissolving  it  in  hot  water  and 
filtering. 

2.  This  a  mixture  of  sulphuretted  hydro-sulphuret  and  of  hydro- 
sulphuret,  which  last  will  crystallize  on  cooling. 

3.  See  general  characters  for  the  rest.     This  compound  is  very 
useful  in  preparing  the  salts  of  baryta ;  see  the  muriate  and  carbo- 
nate. 

SULPHURETTED  HYDRO-SULPHURET  OF   STRONTIA. 

The  same  in  every  respect  as  the  last,  only  the  decomposition  of 
the  sulphate  by  charcoal  is  less  striking. 

LIQUID  SULPHURETS. 

1.  This  name  is  often  given  to  the  hydrogenated  sulphurets, 

2.  Indeed  they  seem  to  consist  generally  of  a  solution  of  sulphur 
in  an  alkali,  combined  with  more  or  less  of  sulphuretted  or  of  bi-sul- 
phuretted  hydrogen. 


SULPHURETTED  HYDRO-SULPHURETS.  351 

3.  According  to  Proust,  a  pure  liquid  sulphuret,  without  sulphuret- 
ted hydrogen,  may  be  formed,  by  withdrawing  the  latter  by  red  ox- 
ide of  mercury.* 

SULPHURETTED   HYDRO-SULPHURET  OF  MAGNESIA. 

By  processes  similar  to  those  pointed  out  above,  magnesia  gives 
but  feeble  indications  of  combining  with  sulphur,  &c.,  and  is  the  last 
of  the  earths  that  gives  any. 

Remarks. — The  elaborate  researches  of  Berthollet,  (1798,)  for- 
merly led  us  to  suppose,  that  when  a  base  is  boiled  with  sufficient 
sulphur,  a  fluid  sulphuret  was  produced,  which  decomposed  water, 
and  generated  sulphuretted  hydrogen,  part  of  which  was  exhaled, 
thus  producing  the  peculiar  odor  of  these  preparations,  and  that  the 
remainder  of  this  gas  combined  with  the  sulphuret,  and  formed  what 
was  called  hydrogenized  sulphuret  ;  and  it  was  thought  to  be  a  suf- 
ficient proof  of  the  truth  of  this  opinion,  that  an  acid  decomposed  the 
preparation,  evolving  sulphuretted  hydrogen  and  precipitating  sulphur 
abundantly,  both  of  which  facts  were  supposed  to  arise  from  the  acid 
seizing  the  base  to  form  a  salt. 

More  recently,  we  are  taught,  that  bi-sulphuretted  hydrogen  is  gen- 
erated in  these  cases,  and  that  the  excess  of  sulphur  is  contained  in 
that  mode  of  combination.  But  I  think  this  cannot  be  all  that  hap- 
pens ;  for  there  is  great  variety  in  the  quantity  of  sulphuretted  hydro- 
gen, which  acids  evolve,  and  of  sulphur  which  they  precipitate  from 
these  preparations.  Sometimes,  although  sulphur  is  abundantly  pre- 
cipitated, very  little  gas  makes  its  escape,  and  at  other  times  it  is 
very  abundant.  I  am  persuaded  that  there  is  often  much  sulphur  in 
solution,  which  is  simply  dissolved  by  the  entire  compound,  and  is 
not  merely  combined  with  the  hydrogen  in  the  form  of  sulphuretted 
or  bi-sulphuretted  hydrogen'.  My  experience  would  lead  me  to  ac- 
cord with  the  following  opinion  of  Dr.  Ure.f 

1.  Sulphuretted  hydrogen,  sulphur  and  the  alkalies  have  the  pro- 
perty of  forming  very  variable  triple  combinations. 

2.  All  these  combinations  contain  less  sulphuretted  hydrogen  than 
the  hydro-sulphurets ;  and 

3.  The  quantity  of  sulphuretted  hydrogen  is  inversely  as  the  sul- 
phur they  contain,  and  reciprocally. 

SULPHURETS. 

I.  Sulphurets  of  alkalies  and  alkaline  earths. 

Remarks. — Until  within  a  few  years,  it  was  supposed  that  the  fu- 
sion of  dry  sulphur  with  the  fixed  alkalies  and  alkaline  earths,  produ- 
ced a  true  sulphuret  of  the  alkaline  body,  and  it  is  still  by  no  means 
certain  that,  under  particular  circumstances,  this  is  not  the  fact.  It  is 
the  opinion  of  Gay  Lussac,  that  a  true  sulphuret  of  an  oxide  is  form- 
ed, provided  the  temperature  is  kept  below  ignition.  "A  une  tem- 

*  Aikin's  Diet.  Vol.  II,  p.  363.  t  Diet.  2d  Ed.  p.  756. 


352  SULPHURETS. 

perature  pen  elevee,  qui  n'atteigne  jamais  la  chaleur  rouge,  ce  corps 
se  combine  avec  les  alcalis  sans  les  decomposer,  et  forme  des  sul- 
fures  d'  oxide."  This  appears  to  me  so  probable,  that  I  shall  here 
preserve  a  notice  of  what  were,  heretofore,  regarded  as  alkaline 
sulphurets. 

1 .  Formed  by  fusion  of  sulphur  with  the  base,  or  decomposition 
of  a  sulphate  by  ignition  with  charcoal  powder.'54' 

2.  Of  a  liver\  color,  if  formed  with  caustic  alkalies,   or  greenish 
yellow,  if  with  their  carbonates. 

3.  Inodorous,  ivhile  dry. 

4.  Decomposed  by  a  higher  degree  of  heat  than  that  by  which 
they  were  formed,  sulphur  being  sublimed,   and  the  base  left  in  the 
bottom  of  the  vessel. 

Chemists  and  physiciansj  were  accustomed  to  use  these  prepara- 
tions in  solution,  but  they  then  ceased  to  be  true  sulphurets ;  for  sul- 
phuretted hydrogen  was  generated,  and  they  passed  to  a  new  condi- 
tion ;  that  of  the  sulphuretted  hydro-sulphurets.  In  making  the 
preparations,  it  is  of  little  importance  whether  we  boil  the  base  and 
sulphur  together,  or  melt  them  together,  and  then  dissolve  them ;  or 
whether  we  dissolve,  in  hot  water,  the  residuum  from  the  decomposi- 
tion of  the  sulphates,  by  ignition  with  charcoal ;  for,  in  either  case, 
by  the  decomposition  of  water,  we  obtain  a  compound  containing 
sulphuretted  or  bi-sulphuretted  hydrogen ;  it  is  fetid,  and  acrid,  and 
liberates  by  the  action  of  acids,  precipitated  sulphur  and  sulphuret- 
ted hydrogen  gas.  In  all  these  cases  also  there  is  a  generation, 
probably  from  the  oxygen^  of  the  water,  of  some  of  the  acids  of  sul- 
phur, and  by  spontaneous  decomposition,  especially  if  the  solution  is 
kept  in  loosely  stopped  vessels,  the  substances  pass  to  the  condition 
of  sulphite  or  sulphate,  ||  and  thus  lose  their  peculiar  properties. 

II.  Sulphurets  of  the  metallic  bases  of  the  fixed  alkalies  and  alka- 
line earths. 


*  In  the  latter  case  they  were  left  in  mixture  with  the  charcoal,  and  could  scarce- 
ly be  exhibited  pure  ;  it  now  appears  that  a  metallic  sulphuret  is  produced  in  this 
manner. 

t  Therefore  called,  in  the  old  language  of  chemistry,  hepar  sulphuris  or  liver  of 
sulphur. 

t  Physicians  prepare  the  sulphuret  of  potash  by  taking  flowers  of  sulphur  and 
potash  or  pearl  ashes,  equal  quantities ;  they  are  melted  in  a  covered  crucible  or 
skillet,  and  then  kept  in  a  close  vessel,  but  are  dissolved  for  use,  in  the  proportion 
of  two  drams  in  a  pint  of  rain  water,  and  this  is  used  as  an  external  wash.  A.  table 
spoonful  is  taken  for  a  dose,  twice  in  a  day ;  used  for  a  variety  of  eruptions,  scald  head, 
psora,  &c.  In  pulmonary  consumption  it  may  be  given,  in  the  above  manner  or  in 
form  of  pills,  from  two  to  live  grains  for  a  dose,  repeated  two  or  three  times  in  a  day. 
It  removes  or  diminishes  the  hectic  fever:  it  has  been  used  internally  as  an  antidote 
against  metallic  poisons  and  to  check  excessive  salivations  from  mercury. —  Coni'd. 

§  Vauquelin  supposed  from  the  oxygen  of  the  alkali. 

Jl  The  preparation  from  the  decomposed  sulphate  of  baryta,  is  particularly  re- 
markable for  passing  back  to  the  condition  of  sulphate,  and  it  often  presents  distinct 
prismatic  crytals. 


SULPHURETS.  353 

It  cannot.be  doubted,  that  many  of  the  compounds  which  were 
formerly  regarded  as  sulphurets  of  the  oxides  of  metallic  bases,  were 
really  sulphurets  of  the  metals  themselves,  and  it  is  now  clearly  as- 
certained that  they  are  formed  in  the  following  modes  and  circum- 
stances. 

1.  By  fusion  of  the  metallic  base  with  sulphur,   or  by  passing  its 
vapor  over  the  metal,  ignited  in  a  porcelain  tube;  the  union  often 
takes  place  with  the  disengagement  of  much  heat  and  light,  resem- 
bling a  combustion,  and  by  many  it  is  regarded  as  such.     Potassium 
and  sodium  are  the  only  alkaline  bases  which  we  are  able  to  try  in 
this  way  ;*  the  same  thing  happens  with  silicium. 

2.  By  heating  the  metallic  bases  in  sulphuretted  hydrogen  gas, 
when  the  sulphur  combines  with  the  metal,  often  with  appearance  of 
combustion,  and  the  hydrogen  gas  is  liberated ;  potassium  and  sodi- 
um exhibit  this  phenomenon  remarkably. 

3.  By  passing  the  same  gas,  or  its  solution  in  water,  into  the  metal- 
ic  solution,  when  sulphurets  are  precipitated  ;  those  metals  that  are 
not  affected   by  sulphuretted  hydrogen,  namely,  iron,  manganese, 
nickel,  cobalt  and  uranium,  are,  like   all  the  other  metallic  solu- 
tions, precipitated  as  sulphurets,  by  the  hydro-sulphurets  of  potassa 
and  ammonia. 

4.  By  heating  sulphur  to  ignition  with  the  oxide  of  the  metal;  the 
oxygen  escapes  in  sulphurous  acid,  and  the  remainder  of  the  sulphur 
combines  with  the  metal. 

5.  By  igniting  the  sulphate  of  an  alkaline  oxide  with  charcoal 
powder,  j-  or  by  passing  the  hydrogen  gas  over  the  ignited  sulphate  ; 
all  the  sulphates  of  these  bodies  are  thus  reduced  at  a  white  heat  and 
if  fusible,  very  quickly.     Perhaps  the  true  limit  between  the  sul- 
phurets of  the  fixed  alkalies  and  alkaline  earths,  and  of  their  metallic 
bases,  will  be  found  below  a  red  heat  for  the  former,  and  at  or  above 
it  for  the  latter.     There  cannot  be  any  doubt  that  true  metallic  sul- 
phurets are  formed,  when  the  alkalies  and  alkaline   earths  are  igni- 
ted with  sulphur,  or  when  a  sulphate  is   decomposed,  at  a  similar 
temperature,  by  charcoal  or  hydrogen. { 

It  is  remarkable  that  during  the  decomposition  of  the  sulphates  by 
charcoal,  the  gases  disengaged  are  found  to  contain  the  whole  of  the 


*  Of  the  common  metals  a  number,  as  iron,  copper,  lead  and  bismuth,  exhibit  this 
phenomenon  in  a  striking  manner;  the  two  former  shew  it  in  a  glass  vessel. 

t  Mr.  Berthier  enclosed  the  sulphate  in  a  covered  crucible  lined  with  a  mixture  of 
clay  and  charcoal  powder. 

t  The  limits  of  this  work  do  not  allow  me  to  cite  more  in  detail,  the  labors  of  Vau- 
quelin,  Ann.  de  Chim.  et  de  Phys.  Vol.  VI,  1817,  or  those  of  Gay-Lussac,  Id.  or 
of  Berthier,  Id.  Vol.  XXII,  or  of  Berzelius,  Vol.  XX.  A  perspicuous  statement 
drawn  from  these  authorities,  may  be  found  in  Dr.  Turner's  Chemistry,  2d  Ed. 
p.  388  ;  I  find  that  it  contains  every  thing  of  importance  in  the  original  memoirs. 

45 


354  SULPHURETS. 

oxygen  that  existed,  both  in  the  oxidized  base  and  in  the  sulphuric 
acid  ;  and  when  hydrogen  is  employed,  the  water  produced,  accounts 
in  the  same  manner,  for  the  whole  of  the  oxygen,  and  there  is  in  either 
case,  no  loss  of  sulphur,  as  it  all  remains  combined  with  the  metallic 
base  forming  a  true  metallic  sulphuret. 

When  the  sulphurets  of  the  metallic  bases  of  the  alkaline  sub- 
stances are  dissolved  in  water,  they  pass  at  once,  to  the  condition  of 
hydro-sulphurets  and  sulphuretted  hydro-sulphurets.  The  decom- 
position of  the  water  appears  to  be  the  means  of  effecting  these 
changes ;  its  oxygen  causes  the  metal  to  pass  to  the  state  of  oxide,  and 
its  hydrogen  with  a  part  of  the  sulphur  forms  sulphuretted  or  bi-sul- 
phuretted  hydrogen  ;  some  of  the  acids  of  sulphur  are  also  formed. 
When  a  sulphuret  is  obtained  by  the  decomposition  of  sulphate  of 
baryta  by  charcoal  and  heat,  and  subsequent  addition  of  boiling  wa- 
ter, there  is  produced,  from  a  strong  solution,  a  very  copious  and 
sudden  deposition  of  white  crystalline  plates  of  hydro-sulphuret  of 
baryta,  while  a  part  of  the  fluid  appears  to  remain  in  the  condition  of 
sulphuretted  hydro-sulphuret  or  bi-hydro-sulphuret  of  baryta.  Sul- 
phurous acid  or  hypo-sulphurous  acid  is  also  produced,  and  combin- 
ing with  a  portion  of  the  oxidized  base  contributes  to  expel  more  sul- 
phuretted hydrogen. 

In  concluding  this  rather  complicated  subject,  it  may  be  well  to 
call  to  the  recollection  of  the  learner,  that  the  following  are  its  great 
divisions. 

1 .  Sulphuretted  and  U-sulphurettcd  hydrogen,  containing  sulphur 
dissolved  in  hydrogen  ;  one  proportion  in  the  former,  and  two  in  the 
latter. 

2.  Hydro-sulphurets,  consisting  of  sulphuretted  hydrogen,  and  an 
oxidized  metallic  base*  of  an  alkaline  substance  ;  in  other  words,  of 
an  alkali  or  an  earth. f 

3.  Sulphuretted  hydro-sulphurets,  consisting  of  bi-sulphuretted  hy- 
drogen, and  oxidized  metallic  bases,  viz.  alkalies  and  earths ;  pro- 
bably containing  also  variable  proportions  of  sulphur  dissolved,  besides 
what  is  united  to  the  hydrogen. 

4.  Sulphurets  of  the  alkalies  and  earths,  formed  below  ignition. 

5.  Sulphurets  of  metallic  bases,  formed  above  ignition  and  con- 
taining no  sulphuretted  hydrogen,  nor  any  uncombined  sulphur. 


*  Ammonia  being  always  exceptecl  as  having  a  different  constitution,  but  still,  it 
forms  a  true  hydro-sulphuret,  and  one  of  the  most  useful, 
t  The  common  metals  are  not  here  brought  into  view. 


CARBON,  355 

SEC.  II. — CARBON— carbo — Latin. 

1.    ITS  IMPORTANCE  AND  WIDE  DIFFUSION. 

(a.)  An  element  of  great  interest,  diffused  through  the  animal  and 
vegetable  kingdoms,  and  largely  in  the  mineral,  either  in  the  form  of 
carbon  or  carbonic  acid,  free  or  combined. 

(b.)  Known  to  the  ancients. — Theophrastus  Eresius,  pupil  and  suc- 
cessor of  Aristotle,  mentions  charcoal  300  hundred  years  before 
Christ,  and  Pliny  describes  the  process  of  burning  it.* 

2.  PRINCIPAL  NATURAL  FORMS  AND  VARIETIES. 

(a.)  DIAMOND. — It  differs  from  charcoal,  in  being  a  non-conduc- 
tor of  electricity,  and  in  nearly  all  its  physical  properties ;  still  it 
is  pure  crystallized  carbon. 

The  proof  rests  on  the  fact,  that  it  is  entirely  combustible  ;  that  it 
is  converted  into  carbonic  acid  gas,  without  any  other  product ;  and 
that  it  forms  steel  by  cementation  with  soft  iron.f  The  combustion 
is  effected  without  difficulty,  in  pure  oxygen  gas  ;  under  the  compound 
blowpipe,  and  in  melted  nitre.  It  differs  from  charcoal  more  in 
its  state  of  aggregation,!  than  in  its  chemical  relations.  Still  it  is 
much  harder  than  we  imagine  ;  a  mass  of  vegetable  charcoal  is  light, 
because  a  great  quantity  of  matter  has  been  expelled  in  the  aeri- 
form state,  and  thus  the  substance  is  made  to  appear  both  soft  and 
light ;  but  its  integrant  particles^  are  hard,  as  will  be  peceived  by 
grinding  them  between  plates  of  window  glass  which  they  will 
scratch,  and  it  is  stated  on  the  authority  of  Prof.  Leslie,  that 
the  sp.  gr.  of  charcoal  is  really  greater  than  that  of  the  diamond. 
Carbon  exists  in  a  transparent  state,  in  the  oils  and  in  alcohol,  and  in 
crystals  of  white  sugar,  from  all  of  which  it  is  easily  developed,  by 
heat,  acids,  and  other  agents  ;  it  is  found  also  in  several  gases. 

(b.)  PLUMBAGO,  or  black  lead. — The  proof  that  this  is  nearly  pure 
carbon,  is  the  same  ;  it  produces  carbonic  acid  by  combustion,  and 
there  is  only  a  small  residuum  of  iron  and  earthy  impurities.  || 

(c.)  ANTHRACITE. — The  same  remark  may  be  made  of  this  ;  it 
is  nearly  pure  carbon. 

There  seems  no  reason  to  doubt  that  the  globules  which  I  obtained 
in  1823,  from  the  plumbago  and  anthracite,  by  the  deflagrator,  arose 
in  part,  from  the  earths  present  in  these  minerals ;  but  with  charcoal, 
I  conceive  it  to  have  been  otherwise,  (see  note,  p.  358,)  and  the 


*  Parkes'  Essays,  Vol.  I,  396.  t  Phil.  Trans.  1815,  p.  371. 

|  Charcoal  is  not  more  different  from  diamond,  than  clay  or  pure  pulverulent  alu- 
mina is  from  the  sapphire  ;  or  chalk  from  Iceland  crystal ;  or  pulverulent  magnesia, 
from  the  same  in  the  boracite ;  or  than  quartz  nectique,  (swimming  flint,)  from  rock 
crystal. 

§  So,  the  integrant  particles  of  pumice  stone  and  tripoli  are  hard,  although  the 
mass  is  soft,  and  that  of  the  former  is  very  light. 

||  For  its  analysis,  see  Am.  Jour.  Vol.  X,  p.  102. 


356  CARBON. 

compound  blowpipe,  evidently  effected,  the  fusion  of  the  entire  plum- 
bago, including  the  carbon,  the  earths  and  iron.* 

(d.)  BITUMINOUS  COAL. — The  basis  of  this  is  carbon,  which,  un- 
der the  name  of  coak,  is  obtained,  after  the  bitumen,  the  inflammable 
gas,  and  other  volatile  ingredients  have  been  expelled  by  heat.  It 
contains  some  earthy  and  metallic  impurities,  but  burns  away  almost 
entirely  in  oxygen  gas,  producing  carbonic  acid. 

3.  ARTIFICIAL  CHARCOAL. 

(a.)  CHARCOAL  is,  after  the  diamond,  the  purest  form  of  carbon  ;  it 
is  prepared  in  the  large  way,  by  a  smothered  combustion  of  billets  of 
wood,  properly  arranged,  so  as  to  admit  a  very  partial  supply  of  air, 
through  holes  at  the  bottom  ;  the  pile  is  covered  with  turf,  earth  or 
clay,  except  a  few  spiracles,  or  one  hole  at  the  top ;  and  these  are 
stopped,  when  the  dark  smoke  is  replaced  by  clear  whitish  clouds. 
The  emission  of  volatile  matter,  consisting  of  inflammable  gases,  va- 
por of  oils,  and  water,  and  pyroligneous  acid,  and  other  things,  chem- 
ically or  mechanically  raised,  finally  ceases;  and  the  heap  is  suffered 
gradually  to  cool,  which  takes  several  days  or  weeks,  according  to  its 
size. 

The  principle  of  the  process  is,  that  the  combustion  of  a  por- 
tion of  the  wood  produces  strong  ignition  in  the  remainder,  and  thus 
expels  every  thing  volatile. 

(b.)  Its  formation  may  be  shewn,  by  plunging  small  pieces  of  wood 
beneath  melted  lead  or  tin,-\  or  beneath  sand  heated  to  redness  in  a 
crucible,  in  a  furnace  ;J  when  cold,  it  should  be  immediately  removed, 
and  corked  up  for  use. 

(c.)  Prepared  also  in  cast  iron  cylinders,  for  the  manufacture  of 
gun  powder,^  and  the  charcoal  is  the  same  from  whatever  wood  pre- 
pared, although  alder,  dog-wood,  and  willow  have  been  heretofore 
preferred.  The  cylinders  are  placed  across  a  furnace,  and  there  is 
vent  only  for  the  aerial  matter,  consisting  of  inflammable  gas,  pyro- 
ligneous acid ||  and  tar,  all  of  which  are  useful  products. 

4.  PROPERTIES. 

(«.)  Slack,  brittle,  shining,  inodorous,  and  easily  pulverized ;  it 
is  so  porous  that  it  is  easy  to  blow  through  it. 


*  See  Am.  Jour.  Vol.  VI,  p.  352. 

t  Arrangement  for  class  exhibition. — A  small  earthen  furnace,  filled  with  burn- 
ing charcoal,  is  supported  by  bricks  or  a  stone  upon  a  table,  and  upon  this  rests  a  large 
ladle  nearly  full  of  melted  lead,  which  should  be  nearly  red  hot,  and  the  wood  held 
by  small  tongs  is  plunged  beneath  it;  the  fluid  metal  will  boil  vehemently,  and  the 
inflammable  gas,  may  be  fired  as  it  rises ;  when  all  is  quiet,  the  charcoal  is  devel- 
oped, and  maybe  cooled  beneath  mercury.  t  Aikin,  Vol.  If,  235. 

§  Or  still  more  neatly,  by  wrapping  a  piece  of  wood  in  platiua  foil,  and  holding  in 
the  flame  of  alcoholic  lamp.  The  liberated  gases  take  fire  and  burn  brilliantly,  and 
well  formed  charcoal  remains  within. — J.  G. 

||  'The  charcoal  made  in  this  manner,  is  kept  from  the  air  when  it  is  to  be  used  for 
the  manufacture  of  gun  powder ;  it  has  not  more  than  half  the  specific  gravity  of 


CARBON.  357 

(b.)  Unchanged  by  heat,  in  closed  vessels,  except  that  it  grows 
firmer,  and  harder,  and  blacker,  and  shrinks ;  it  will  then  very  de- 
cidedly scratch  glass,  and  wear  a  file.*  With  the  best  pieces,  one 
can  write  his  name  on  window  glass. 

!c.)   Unaltered  by  air  and  water,  and  exempt  from  decay. 
d.  If  well  prepared,  it  conducts  electricity,  but  is  a  bad  conduc- 
tor of  heat.f 

(e.)  When  once  thoroughly  made,  it  retains  for  a  long  time, 
its  power  of  conducting  electricity.  Heated  without  contact  of  air, 
it  emits  inflammable  gases  and  nitrogen^  % 

(f.)  Jlfter  being  ignited,  it  absorbs  gases  without  alteration  ;§  this 
is  shewn  by  placing  on  the  quicksilver  bath,  a  piece  recently  extin- 
guished, and  covered  by  a  jar.  This  power  is  much  diminished  by 
pulverizing  the  charcoal.  The  following  are  the  results  of  Saus- 
sure,  with  box  wood  charcoal,  the  most  powerful  species  ;  the  time 
was  from  24  to  36  hours ;  the  charcoal  was  first  ignited,  cooled  in 
mercury,  and  then  placed  in  the  gas. 

Gaseous  ammonia  90  times  the  volume  of  the  charcoal ;  do.  mu- 
riatic acid  85  ;  sulphurous  acid  65  ;  sulphuretted  hydrogen,  55 ; 
nitrous  oxide,  40 ;  carbonic  oxide,  35 ;  olefiant  gas,  35 ;  carbonic 
oxide,  9.42  ;  oxygen,  9.25  ;  azote,  7.5  ;  light  gas  from  moist  charcoal 
5. ;  hydrogen,  1.75  ;  very  light  charcoal  scarcely  absorbs  at  all. 

The  power  of  absorption  in  charcoal  bears  no  relation  to  its  chemi- 
cal attraction  for  the  gas  or  vapor,  which,  by  heating  the  charcoal,  is 
in  general  recovered  unaltered. 

Those  gases  that  cannot  be  condensed  into  the  liquid  state,  are 
the  least  absorbed  by  charcoal,  and  the  reverse  is  true,  very  nearly 
in  proportion  to  the  ease  with  which  they  are  condensed.  Vapors- 


common  charcoal ;  although  better  for  gun  powder,  it  is  not  preferred  by  the  iron 
manufacturer.  The  loppings'of  young  trees,  called  crop  wood,  are  now  generally 
used  in  England.  Abundance  of  a  substance  like  tar  is  produced,  which  Mr.  Parkes 
says  is  an  excellent  preservative  of  wood,  against  decay  and  insects. — Essays,  Vol. 
I,  p.  399. 

The  proportion  of  charcoal  obtained  from  different  woods  varies  from  15  to  26  per 
cent ;  the  average  of  21  trials  gave  nearly  20  per  cent. — Parkes*  Essays,  Vol.  I, 
p.  408. 

Fir  gave  18.17,  lignum  vitae  17.26,  box  20.25,  beech  15,  oak  17.40,  mahogany 
15.75. — Allen  and  Pepys.  For  a  fuller  table,  see  p.  363. 

Wood,  burned  in  the  open  air  leaves  only  about  l-200th,  or  l-250th  of  the  wood, 

but  the  charcoal  is  said  to  contain  l-50th  of  its  weight  of  alkaline  and  earthy  salts. 

Turner. 

*  Even  in  its  common  state,  good  charcoal  will  wear  window  glass. 

t  Lampblack  is  prepared  from  the  combustion  of  oils  and  resins.  We  may  col- 
lect it  by  receiving  the  smoke  of  a  lamp  upon  a  saucer,  or  by  burning  a  piece  of 
pine  knot  or  rosin,  under  suspended  sacking.  In  the  arts,  the  refuse  resin  and  pitch 
are  burned  in  a  peculiar  furnace,  furnished  with  long  flues,  terminating  in  a  close 
chamber,  the  ceiling  of  which  is  covered  with  porous  cloth  to  catch  the  soot. 

t  Mem.  d'  Arcueil,  T.  II,  p.  484. 

§  Jour,  de  Phys.  T.  XXIII,  and  LVIII,  and  Ann.  de  Chim.  T.  XXXII. 


358  CARBON. 

are  more  easily  absorbed  than  gases,  and  liquids  more  easily  still.  It 
evidently  depends  upon  the  porous  form  of  the  charcoal,  and  plum- 
bago does  not  possess  it  at  all.  The  power  seems  to  be  analagous 
to  that  of  capillary  attraction  in  other  solids.  When  oxygen  is  ab- 
sorbed, carbonic  acid  is  formed  at  the  end  of  several  months  ;  if  char- 
coal is  impregnated  with  sulphuretted  hydrogen,  and  exposed  to  the  air 
or  to  oxygen  gas,  sulphur  is  evolved,  and  water  formed,  the  gas 
being  destroyed,  and  considerable  heat  produced,  so  as,  in  some 
cases,  to  produce  in  a  few  minutes,  detonation  with  oxygen  gas,  and 
more  or  less  heat  is  always  evolved  when  gases  are  absorbed  by  char- 
coal.* In  general  after  24  hours,  the  absorption  is  not  increased,  ex- 
cept in  the  case  of  oxygen  gas,  which  goes  on  absorbing  for  years, 
in  consequence  of  the  formation  of  carbonic  acid.  The  gas  is  easily 
extracted  by  the  air  pump,  and  during  its  extrication,  cold  is  pro- 
duced. Charcoal  which  has  absorbed  a  gas  will  give  it  out  en- 
tirely by  being  heated  again,  and  very  strikingly  with  ebullition,  by 
plunging  it  into  boiling  hot  water.  The  charcoal  can  be  as  effect- 
ually prepared  for  absorbing  gases  by  the  air  pump  as  by  ignition. f 
This  property  is  common  more  or  less  to  all  porous  bodies  ;  asbes- 
tos, silk,  meerschaum,  adhesive  slate,  agaric  mineral,  wool,  linen 
thread,  plaster  of  Paris  solidified  by  water,  &c.  have  been  made  sub- 
jects of  similar  experiments.  { 

(g.)  By  exposure  to  the  air,  charcoal  increases  in  weight,  by  ab- 
sorption of  water,  air,  &c.,  f  of  which  is  water.§  By  a  week's  ex- 
posure, lignum  vita3  gained  9.6  per  cent.,  fir  12.0,  box  14.0,  beech 
16.3,  oak  16.5,  mahogany  18.0. — Allen  and  Pepys. 

(h.)  Infusible  by  any  heat  which  we  can  apply,  except  that  of  gal- 
vanism.\\ 

(i.)  Insoluble  in  water,  although  at  a  red  heat,  it  decomposes  that 
fluid,  (vide  carburetted  hydrogen.) 


*  Proportioned  to  the  rapidity  and  amount  of  absorption ;  25°  in  the  case  of  car- 
bonic acid. 

t   Quere — Whether  also  for  conducting-  galvanism,  and  for  antiseptic  agency  ? 

\  Turner,  2d  Ed.  p.  235,  and  Vasel,in  Sweigger's  Jour. 

§  Charcoal  absorbs  from  air  more  oxygen  than  nitrogen ;  when  recently  ignited 
and  confined  in  air,  over  mercury,  it  left  only  8  per  cent.  ;  and  if  from  a  state  of 
full  ignition,  it  be  plunged  into  water,  and  then  confined  in  air  over  mercury,  the 
oxygen  is  nearly  or  quite  all  absorbed,  leaving,  as  is  said,  pure  nitrogen.  We  are  not 
informed  whether  the  pure  oxygen  can  be  recovered  by  heating  the  charcoal. 

||  Fusion  of  char  codify  the  use  of  Dr.  Hare's  Deflagrator.  The  poles  being  ter- 
minated by  well  prepared  charcoal,  a  knob  of  fused  matter  appears  on  the  copper  or 
negative  pole,  sometimes  half  an  inch  in  length,  while  a  cavity,  corresponding  in 
position,  appears  on  the  zinc  or  positive  pole,  and  if  the  pieces  are  made  to  change 
places,  the  knob  and  cavity  are  transferred  from  side  to  side.  The  knob  appears 
to  come  from  the  opposite  pole,  and  is  evidently  derived  from  the  charcoal.  It  is 
very  difficult  to  burn,  but  if  heated  either  in  oxygen  gas  by  the  sun's  rays,  or 
in  common  air,  or  mixed  with  nitrate  or  chlorate  of  potash,  it  produces  carbonic 
acid.  On  an  ignited  iron  in  the  air,  it  wastes  slowly  away.  It  is  smooth  and  glis- 
tening, with  semi-metallic  hues;  its  color  gray,  or  almost  black;  not  fibrous  or 


CARBON.  359 

(j.)  Plunged  into  mercury,  or  merely  resting  on  it,  it  absorbs 
much  of  that  metal  into  its  pores. 

(k.)  Heated  in  contact  with  common  air,  it  burns  away  entirely  ; 
very  rapidly r,  and  wholly,  if  immersed  in  oxygen  gas  in  sufficient 
quantity.  A  piece  of  charred  bark  burns  best,  and  with  lively  scin- 
tillations. 

(/.)  Sulphuric  acid  boiled  on  charcoal  powder  is  decomposed,  and 
sulphurous  acid  gas  is  liberated. 

(m.)  The  decomposition  of  the  sulphates  by  charcoal,  is  a  striking 
instance  of  its  action  on  sulphuric  acid. 

(n.)  To  prepare  charcoal  for  clarification;  take  that  which  is  well 
burned,  pulverize  and  sift  it ;  heat  it  strongly  away  from  the  air,  as 
in  a  crucible  with  a  small  hole  in  the  cover,  or  covered  with  sand ; 
it  must  then  be  bottled  tight,  till  it  is  wanted. 

(0.)  Tincture  of  alkanet,  diluted  with  water,  mixed  with  well  pre- 
pared charcoal,  and  simmered  over  the  fire,  and  then  thrown  upon  a  fil- 
ter, comes  through  perfectly  limpid.  Mixed  with  common  vinegar  or 
wine,  a  thick  froth  rises,  and  the  liquors  are  clear  after  filtration.  It 
is  sometimes  necessary  to  boil  the  vinegar  upon  the  charcoal. 

(p.)  Ditch,  sink,  or  puddle  water,  or  even  that  of  a  surgeon's  tub 
is  thus  rendered  limpid,  inodorous,  and  insipid ;  and  rancid  oils  are 
restored  by  repeated  filtration  through  charcoal. 

(q.)  The  prepared  charcoal  is  an  excellent  dentifrice ;  that  from 
the  shell  of  the  cocoa  nut  is  preferred  ;  the  charcoal  of  the  kernels 
of  nut  fruit  is  very  delicate,  and  that  of  carbonized  wheat  bread  is 
very  good.* 

(r.)  Solutions  of  impure  acid  of  tartar,  crude  tartar,  crude  nitre, 
and  other  salts  are  rendered  colorless  by  being  boiled  with  charcoal 
powder,  and  are  thus  made  to  crystallize  in  snow  white  purity. 

(5.)  Impure  carbonate  of  ammonia,  sublimed  from  an  equal  weight 
of  charcoal  powder,  is  rendered  white  and  deprived  of  its  foetid 
smell.  Charcoal  also  destroys  the  heavy  sickening  odor  arising  from 
oiled  and  gummed  silks,  such  as  those  of  which  hat  cases  and  um- 
brella coverings  are  made,  and  it  speedily  removes  any  unpleasant 


porous  ;  it  has  no  resemblance  to  charcoal ;  sinks  as  readily  in  strong  sulphuric 
acid,  as  it  before  floated  on  water  with  its  volume  half  out ;  its  gravity  was  there- 
fore increased  four  times,  compared  with  the  charcoal  in  mass. 

This  observation  was  first  made  by  myself  in  March  1823,  and  has  been  repeat- 
ed many  times  since  ;  with  a  powerful  deflagrator,  it  constantly  occurs.  The  sub- 
stance resembles  greatly,  the  residuum  found  in  the  iron  gas  bottles,  and  there 
seems  no  reason  to  doubt  that  it  proceeds  from  the  volatilization  and  fusion  of  the 
charcoal  along  with  whatever  foreign  substances  it  may  contain.  The  objections 
of  Prof.  Vanuxem  seem  to  have  related  to  a  different  substance.— Am.  Jour.  Vol. 
IV,  p.  371. 

*  Soot  is  one  of  the  very  best  dentifrices ;  for,  besides  the  carbon,  there  are  the 
detergent  ammoniacal  salts,  and  a  bitter  principle,  and  other  active  agents. 


360  CARBON. 

% 

effluvium  from  clothes,  &c.  by  being  wrapped  in  them.  "It  also 
sweetens  bilge  water." 

(t.)  Malt  spirits,  distilled  from  charcoal  are  deprived  of  their  disa- 
greeable flavor  ;  if  too  much  charcoal  is  used,  the  spirit  is  decom- 
posed, as  is  vinegar  also.  Charcoal,  for  this  purpose,  is  prepared 
by  heating  it  red  hot  in  a  furnace  ;  it  is  then  ground  in  a  mill  and 
barrelled  or  put  to  immediate  use  by  having  the  spirit  placed  over  it. 

(u.)  Eight  or  ten  pounds  of  the  spirit  macerated  for  eight  or  ten 
days  on  two  ounces  of  charcoal,  is  improved  in  flavor. 

(v.)  Water  become  putrid  in  casks,  is  restored  by  filtration 
through  charcoal,  especially  if  a  few  drops  of  sulphuric  acid  be  added. 

(w.)  The  odor  of  alcoholic  solutions  of  resins  and  balsams  is  not 
•  destroyed  by  charcoal,  although  their  color  is  ;  essential  oils  do  not 
lose  their  smell. 

( a?.)  Distilled  waters  and  many  vegetable  tinctures,  and  litmus, 
and  indigo,  and  other  lakes  and  pigments,  become  colorless  when 
their  aqueous  solutions  are  filtered  through  charcoal. 

(y.)  Gum-resins,  as  opium,  assafoetida,  &ic.  suspended  in  water, 
lose  their  odors. 

(z.)  Tainted  meat  is  restored  by  rubbing  or  boiling  it  with  charcoal 
powder ;  and  if  daily  renewed,  it  preserves  meat  from  putrefaction. 

(aa.)  The  inside  of  water  casks  is  charred  to  preserve  the  water 
from  putridity  in  long  voyages,  and  the  ends  of  posts  to  keep  them 
from  rotting. 

(bb.)  The  facts  under  (t.)  and  (u.)  are  true  of  rum  and  other 
varieties  of  ardent  spirit. 

(cc.)  Proper  proportion  is  essential  to  success  in  these  experiments. 

(dd.)  The  same  portion  of  charcoal,  if  re-ignited,  may  be  used 
repeatedly. 

(ee.)  Minimal  charcoal  is  a  more  powerful  antiseptic  than  vegeta- 
ble ;  it  is  obtained  by  calcining  bones  in  close  vessels.* 

(ff.)  Charcoal,  if  undisturbed  when  in  the  act  of  being  formed, 
preserves  the  organization  of  the  substance  from  which  it  is  derived; 
"  the  wire  marks  of  paper  and  the  thread  of  linen,  are  still  seen  with 
distinctness,"  after  being  carefully  burned. 

Grains  of  wheat  and  rye  charred  in  Herculaneum,  by  the  volcanic 
eruption,  A.  D.  79,  were  easily  distinguished  from  each  other,  and 
an  arrow  head  has  been  charred  so  as  to  preserve  the  form  of  the 
feather. — ParJces. 

(gg.)  The  charcoal  of  the  heaviest  wood  requires  most  air,  and 
gives  the  most  heat,  and  is  best  fitted  for  the  reduction  of  metallic 
oxides ;  "  while  lighter  wood  preserves  a  glowing  heat  with  a  less 
draught  of  air."  If  wood  be  stripped  of  its  bark  before  it  is  carbon- 


*  Ann.  de  Chiin.  79,  80 ;  Jour,  of  Science,  IV,  367. 


CARBON.  361 

ized,  it  does  not  crackle  and  fly.  For  black  crayons,  willow  affords 
the  best  charcoal,  it  being  uniformly  soft.  Ivory  black  is  the  coal  of 
ignited  ivory  prepared  in  close  vessels ;  the  common  ivory  black  is 
often  made  from  bones. 

(hh.)  The  durability  of  charcoal  is  seen  in  the  figures  on  the  dial 
plates  of  steeples,  which  often  stand  out  in  bold  relief,  while  the  rest  of 
the  wood,  painted  white,  is  worn  away. 

(ii.)  Lampblack,  ignited  in  a  crucible,  and  cooled  before  it  is  un- 
covered, and  the  charcoal  which  Is  procured  by  passing  the  vapor  of 
oils  or  of  alcohol  through  ignited  tubes,  is  the  purest  carbon  that 
art  can  prepare.  It  is  an  impalpable  black  powder,  and  more  than 
twice  as  heavy  as  water.* 

(jj.)  Bistre,  a  beautiful  brown  pigment,  is  prepared  from  an 
aqueous  infusion  of  wood  soot. 

(kk.)  Animal  charcoal  is  more  dense  and  less  combustible  than  ve- 
getable, and  contains  phosphate  of  iron ;  it  is  distinguished  from  ve- 
getable, as  the  latter  burns  on  an  ignited  iron  into  white  ashes,  form- 
ing a  bitterish  liquor  with  sulphuric  acid,  but  the  residuum  of  animal 
matter  is  much  less  soluble,  and  forms  a  compound  having  a  very  dif- 
ferent taste. f 

(II.)  Charcoal  is  very  effectual  in  depriving  treacle  or  molasses  of 
its  peculiar  taste  ;  twenty  four  pounds,  diluted  with  an  equal  weight 
of  water,  and  boiled  for  half  an  hour  with  six  pounds  of  pulverized 
charcoal,  were  entirely  deprived  of  the  empyreumatic  taste  and  smell, 
and  being  strained  and  evaporated  to  a  proper  consistence,  had  the 
flavor  of  good  sugar.  {  Honey  may  be  treated  in  the  same  manner, 
and  with  the  same  effect.^ 

(mm.)  The  due  preparation  of  charcoal  is  of  the  last  consequence 
to  success  in  these  operations. — Common  charcoal  is  almost  inert ;  it 
is  indispensable  that  it  be  fresh  made  ;  or  re-ignited,  and  that  it  be 
secluded  from  the  air  till  it  is  used. 

(nn.)  Charcoal  is  used  in  polishing  brass  and  copperplates  and 
lanthorn  leaves ;  in  tracing  the  outlines  of  drawings,  and  in  giving 
some  peculiar  tints  to  glasses  colored  in  imitation  of  the  gems.|| 

(oo.)  The  ancients  knew  that  charcoal  will  not  decay. — The  piles 
driven,  more  than  than  two  thousand  years  ago,  in  founding  the  tem- 
ple of  Ephesus,  were  charred,  and  those  that  support  the  houses 


*  Davy's  Elements,  p.  299.  A  very  pure  charcoal  is  prepared  also  from  sugar 
and  starch. 

t  Parkes'  Essays,  Vol.  I,  p.  414. 

t  Charcoal  has  been  applied  to  the  refining  of  sugar,  and  a  patent  was  taken  out 
for  it  some  years  ago  in  London.  Mr.  Parkes  says,  that  finer  loaves  of  sugar  than 
were  manufactured  at  any  other  establishment  in  London,  were  as  he  supposes,  pro- 
duced in  this  manner. 

§  Parkes'  Essays,  Vol.  I,  p.  419.  ||  Parkes. 

46 


,J62  CARBON. 

in  Venice  had  undergone  the  same  process.  Dr.  Robinson,  in  his  in- 
troduction to  Dr.  Black's  lectures,  says,  "About  forty  years  ago,  a 
number  of  pointed  stakes  were  discovered  in  the  bed  of  the  Thames, 
in  the  very  spot  where  Tacitus  says  that  the  Britons  fixed  a  vast 
number  of  such  stakes,  to  prevent  Julius  Ca3sar  from  passing  his 
army  over  by  that  ford.  They  were  all  charred  to  a  considerable 
depth,  and  retained  their  form  completely ;  and  were  so  firm  at  the 
heart,  that  a  vast  number  of  knife  handles  were  manufactured  from 
them,  and  sold  as  antiques,  at  a  high  price."* 

5.  POLARITY. — Electro-positive;  it  is  attracted  to  the  negative  pole. 

6.  COMBINING  WEIGHT  6,  hydrogen  being  1. 

7.  MEDICAL  AND  OTHER  USES. — A  preference  is  entertained  by 
some  for  charcoal  made  from  particular  substances,  as  from  cedar  or 
cork ;  it  should  be  newly  prepared  or  recently  heated,  j-     It  is  thought 
to  correct  a  vitiated  state  of  the  stomach  and  bowels,  and  has  been 
celebrated  in  some  stages  of  dyspepsia,   and  in  dysentery  and  other 
diseases  of  the  alimentary  canal.     The  dose  cannot  be  critical ;  from 
10  grains  to  a  table  spoonful  may  be  given,  two  or  three  times  a  day.J 
It  is  applied  with  much  advantage  to  foul  ulcers,  whose  fetor  it  cor- 
rects,  and  in  the  form  of  poultice  to  sores  that  are  tending  to  gan- 
grene. 

8.  MISCELLANEOUS. 

(a.)  Charcoal  is  said  to  be  better  if  the  bark  is  left  on  the  wood, 
which  should  not  be  split ;  pieces  of  six  or  seven  inches  in  diameter 
are  easily  charred. §  Coak  is  the  carbon  of  mineral  coal ;  it  is  pre- 
pared by  a  process  resembling  in  principle  that  for  charcoal ;  it  pro- 
duces an  intense  fire,  and  is  much  used  in  England  in  the  manufac- 
tures, especially  of  iron. ||  A  charcoal  is  also  extracted  from  peat. 
The  following  table  shows  the  proportion  of  volatile  matter,  charcoal 
and  ashes,  in  100  parts  of  different  woods. — Ure. 


*  I  saw  one  of  these  stakes  in  the  British  Museum ;  the  charcoal  on  the  outside 
and  the  wood  within,  were  apparently  as  perfect  as  the  day  it  was  driven. 

t  If  it  is  to  be  applied  on  a  foul  ulcer  or  sore,  it  should  be  taken  red  hot  from  the 
fire,  pulverized  immediately  in  a  metallic  mortar,  and  used  as  soon  as  cold,  and  any 
,that  remains  should  be  bottled,  tight  from  the  air.  +  Coxe. 

§  It  is  conjectured  that  in  the  charring  of  wood,  portions  of  it  are  sometimes  con- 
verted into  pyrophorus,  and  that  explosions  in  powder  mills  may  occasionally  be 
owing  to  this  cause. 

||  One  ton  of  bituminous  coal  yields  from  700  to  1100  Ibs.  of  coak.  Much  bitumen 
and  other  volatile  products  are  lost  in  the  usual  way  of  charring,  but  Lord  Dundo- 
nald,  by  heating  the  coal  in  a  range  of  eighteen  or  twenty  stoves,  with  as  little  ac- 
cess of  air  as  possible,  and  conducting  the  smoke  through  horizontal  tunnels,  and 
finally  into  a  brick  tunnel  100  yards  long,  and  covered  at  top  by  water,  succeeded 
in  obtaining  nearly  3  per  cent,  of  bitumen  in  the  form  of  tar ;  28  barrels  of  it  yielded 
21  of  tar,  and  the  volatile  parts  gave  materials  for  varnish,  besides  ammonia. —  Ure. 


SULPHURET  OF  CARBON, 


563 


Oak, 
Ash, 
Birch, 
Norway  Pine, 

Mahogany, 
Sycamore, 

Holly, 

Scotch  Pine, 

Beech, 

Elui, 

Walnut, 

American  Maple, 

Do.       Black  Beech, 
Laburnum, 

Lignum  Vitae, 
Sallow, 


Volatile 

Matter. 

76.895 

81.260 

80.717 

80.441 

73.528 
79.20 


Charcoal.  Ashes. 


Charcoal  by 


22.682 
17.972 
17.491 
19.204 

25.492 
19.734 


0.423 
0.768 
1.792 
0.355 

0.980 
1.068 


78.92       19.913     1.162 


83.095 
79.104 
79.655 
78.521 
79.331 

77.512 
74.234 

72.643 

80.371 

16.456 
19.941 
19.574 
20.663 
19.901 

21.445 
24.586 

26.857 
18.497 

0.449 
0.955 
0.761 
0.816 
0.768 

1.033 
1.180 

0.500 
1.132 

Proust. 
20. 
17. 

20. 

Black  Ash, 
25. 

Willow. 

17. 

Heart  of  Oal 
19. 


Guaiacum. 
24. 


Kumford. 
43.00 


44,18 


76.304     23.280     0.416 


43.27 


42.23 


Poplar. 
4357 

Lime, 
43.59 


the 


s 


Chesnut, 

(b.)  Charcoal,  in  the  form  of  lampblack  and  plumbago,  is  among  t 
most  enduring  of  paints,  and  forms  a  firm  body  with  oil.  Plumbago 
used  for  lubricating  machinery,  for  making  crucibles,  for  protecting 
iron  from  rust,  and  to  give  it  lustre.  Charcoal  with  oil  forms  print- 
er's ink  ;  with  sulphur  and  nitre,  gunpowder  ;  with  iron,  by  cementa- 
tion, steel  ;  it  is  used  to  exclude  or  to  confine  heat  ;  it  is  a  very  ex- 
cellent fuel,  and  it  is  employed  with  advantage,  after  being  thorough- 
ly ignited,  to  surround  that  part  of  lightning  rods  which  enters  the 
ground  .  —  Thenard. 

(c.)  Charcoal  is  of  great  utility  in  reducing  the  metals,  both  in  raising 
the  necessary  heat  and  in  detaching  oxygen  from  the  oxides.  Carbon, 
in  the  form  of  diamond  is  the  most  beautiful  of  ornaments,  and  the 
best  substance  to  cut  glass,  and  to  afford  a  cutting  powder  to  polish  the 
hardest  bodies,  diamond  itself  not  excepted.  The  water  of  the  Seine, 
rendered  turbid  by  mud  in  the  winter,  is  purified  and  made  potable,  by 
passing  through  charcoal,  placed  between  two  layers  of  sand,  and 
these  between  two  others  of  gravel  and  pebbles.  —  Id. 

(d.)  It  is  exceedingly  abundant  in  nature  ;  it  exists  in  all  animal  and 
vegetable  bodies  ;  in  all  the  varieties  of  natural  coal,  and  bitumens, 
and  petroleum  and  naptha  ;  in  the  carbonates  of  lime,  and  other  min- 
eral carbonates  ;  in  carbonic  acid,  both  free  in  the  air,  and  dissolved 
in  water.;  and  in  the  carburetted  hydrogen  gases  and  carbonic  oxide  ; 
and  its  chemical  and  natural  history  involves  a  vast  number  of  inter- 
esting and  important  facts. 

SULPHURET  OF  CARBON. 

1.  PREPARATION. 

(a.)  A  porcelain  tube,  one  inch  and  a  half  in  diameter,  coated  with 
fire  lute,  and  partly  filled  with  fragments  of  recently  ignited  charcoal^ 


364  SULPHUREt  OF  CARliON. 

is  placed  a  little  inclined  across  a  furnace ;  at  one  end  a  recurved 
glass  tube  dips  into  water,  and  the  other  end  is  open.  The  furnace 
being  in  action,  a  fragment  of  sulphur  is  pushed  along  by  a  wire 
till  it  is  near  the  charcoal,  taking  care  to  exclude  the  air  as  much  as 
possible ;  the  open  end  of  the  tube  is  then  stopped,  gas  passes  in 
abundance,  and  a  liquid  collects  beneath  the  water ;  more  bits  of 
sulphur  may  be  introduced,  till  enough  of  the  liquid  is  obtained,  and 
it  is  said  that  half  a  pint  may  be  procured  in  a  day. 

(b.)  The  following  process  I  find  to  be  a  good  one,  A  tube  of  iron 
is  placed  across  Black's  furnace,  as  a  protection  to  a  tube  of  porcelain 
which  is  passed  through  it.  A  glass  flask  containing  flowers  of  sulphur, 
coated  with  lute  of  sand,  clay  and  rye  flour,  is  connected  with  one  end 
of  the  iron  tube,  and  at  the  other  is  a  glass  tube  passing  into  water, 
contained  in  a  vessel  surrounded  by  ice.  Pieces  of  charcoal,  recent- 
ly ignited,  are  placed  in  the  porcelain  tube,  and  heat  is  applied  by 
a  chafing  dish  under  the  flask  ;  the  sulphur  is  slowly  volatilized 
through  tire  charcoal ;  the  two  combine,  and  the  desired  yellow  liquid 
drops  from  the  mouth  of  the  tube.  The  principal  point  is  to  bring- 
the  sulphur  into  contact  with  the  charcoal  when  it  is  very  hot  and 
has  ceased  to  emit  gases. 

(c.)  Another  process,  stated  also  to  be  a  good  one,  is  to  distil  na- 
tive iron  pyrites,  (bi-sulphuret  of  iron,)  with  one  fifth  of  its  weight  of 
charcoal  powder. 

2.  PROPERTIES. 

(«.)  After  being  re-distilled  at  a  heat  not  exceeding  100°  or  110° 
Fahr.,  from  some  dry  muriate  of  lime  placed  in  a  retort,  it  is  color- 
less, transparent  and  limpid;*  its  refractive  power  very  high. 

{b.)  Taste  acrid,  pungent,  and  somewhat  aromatic;  smell  nauseous 
and  fetid,  but  unlike  that  of  sulphuretted  hydrogen.  Inflammable, 
and  its  combustion  produces  sulphurous  and  carbonic  acid  gases. 
Insoluble  in  water. 

(c.)  Sp.  gr.  1.27;  boils  at  106°  or  110°,  does  not  freeze  at  60°; 
very  volatile,  at  63.5  Fahr.  its  vapor  sustains  a  column  of  mercury 
7.36  inch  high,  and  during  its  evaporation  produces  so  much  cold  as 
to  freeze  mercury.  The  thermometer  ball  is  covered  with  fine  lint, 
moistened  with  the  liquid,  and  placed  under  the  receiver  of  an  air 
pump.  A  spirit  thermometer  at  the  same  time  indicated  —80. 

(d.)  Not  decomposed,  by  heat  alone,  at  any  temperature ;  but  it  is 
decomposed  by  being  transmitted  over  ignited  iron  or  copper  turn- 
ings ;  also  by  peroxide  of  iron ;  or  by  heating  potassium  in  its  vapor, 
when  there  is  a  brilliant  ignition  ;  the  sulphur  always  combines  with 
the  metal  and  liberates  the  carbon. 

(e.)  It  is  very  combustible,  and  produces  sulphurous  and  carbonic 
acid ;  a  little  sulphur  remains  unburnt.  Placed  in  oxygen  gas  or 

*  Sometimes  a  little  milky  and  opaque  at  first,  but  becomes  limpid  the  next  day. 


CARBONIC  AC1U  365 

deutoxide  of  nitrogen,  it  renders  it  explosive.     Soluble  in  volatile 
oils,  in  ether  and  in  alcohol,  and  precipitable  by  water. 

(f.)  Evaporation  from  water  causes  it  to  congeal. 

3t  COMPOSITION. — 85  sulphur  to  15  carbon,  and  it  is  supposed  to 
contain  2  proportions  of  sulphur  1 6  X  2  =  32  and  1  carbon  6  =  38  for  its 
chemical  equivalent.  This  compound  was  called  alcohol  of  sulphur 
by  Lampadius,  its  discoverer.* 

HYDRO-XANTHIC  ACID. — (favdo?,  yellow.) 

The  sulphuret  of  carbon  is  generally  unaffected  by  acids,  but  the 
nitro-muriatic  acid  produces  from  it  a  yellow  acid,  whose  nature  is 
not  yet  exactly  ascertained. f  Its  discoverer,  M.  Zeise,  (Copenha- 
gen,) regards  it  as  a  compound  of  sulphur  and  carbon  for  a  base, 
with  hydrogen  for  an  acidifier.  It  combines  with  alkalies,  neutral- 
izing them,  and  forming  peculiar  crystallizable  salts.  The  subject 
seems  to  need  farther  examination.  J 

Remark. — It  was  announced  last  year,  in  Paris,  that  phosphorus, 
remaining  six  or  eight  months  in  bi-sulphuret  of  carbon,  attracted 
away  the  sulphur,  and  left  the  carbon  to  crystallize  into  true  dia- 
mond ;  it  was  sajd  that  the  Parisian  jewellers  pronounced  it  to  be 
genuine,  but  the  latest  accounts  state  that  the  small  crystals  obtained 
appear  to  be  siliceous. 

CARBONIC  ACID. 

1.  COMBUSTION  OF  CARBON  IN  VARIOUS  FORMS. 

(a.)  It  has  been  already  mentioned,  that  Sir  Isaac  Newton  sup- 
posed the  diamond  to  be  a  coagulated  combustible,  because  it  re- 
fracted light  so  powerfully.  This  sagacious  conjecture  has  been  con- 
firmed by  the  actual  combustion  of  the  diamond,  and  the  products 
having  been  collected  are  found  to  be  carbonic  acid.§ 


*  Crell's  Annals,  179G,  II.— Cited  by  Turner. 

t  Berzelius  supposes  it  to  be  a  compound  of  muriatic,  carbonic  and  sulphurous 
acid  gases. 

t  Ann.  de  Chim.  et  de  Phys.  Vol.  XXI,  and  Ann.  Phil.  N.  S.  Vol.  IV.  The- 
nard,  5th  ed.  Vol.  I,  p.  440. 

§  The  Emperor  Francis  I,  exposed  a  quantity  of  diamonds  and  rubies  to  an  intense 
heat,  the  rubies  remained  unaltered,  but  the  diamonds  disappeared.  The  Florentine 
academicians,  by  means  of  the  large  burning  glass  of  Tschirhaucen,  in  the  pres- 
ence of  Cosmo  III,  Duke  of  Tuscany,  dissipated  several  diamonds  in  the  year  1694. 
These  experiments  were  repeated  with  equal  success  by  Darcet,  Rouelle,  Macquer, 
and  other  French  chemists,  who  ascertained  that  the  diamond  was  not  merely  dis- 
sipated, but  that  it  actually  burnt  with  a  visible  flame.  Count  de  Sternberg,  a 
Bohemian  gentleman,  fastened  a  diamond  to  red  hot  iron,  and  plunged  it  into  oxygen 
gas,  when  the  combustion  of  the  iron  set  fire  to  the  diamond,  which  burnt  with  a 
very  brilliant  flame.  Lavoisier  and  Cadet  proved  that  the  diamond  does  not  burn 
after  the  oxygen  gas  is  exhausted.  But  these  experiments  went  only  to  prove  that 
the  diamond  is  combustible.  No  attention  had  been  paid  to  the  products  of  the 
combustion,  until  Lavoisier,  in  1777,  undertook  a  series  of  experiments  on  a  large 
scale,  to  ascertain  this  point.  The  result  was  found  to  be,  that  the  diamond  when 
"burnt  in  oxygen  gas,  is  converted  wholly  into  carbonic  acid  gas.  The  conclusion 


366  CARBONIC  ACID. 

(b.)  A  coated  glass  or  porcelain  tube  filled  with  charcoal  that  has 
been  heated  till  it  has  ceased  to  yield  any  gas,  is  placed  across  a  fur- 
nace and  ignited  ;  one  end  being  connected  with  a  gazometer  to  af- 
ford oxygen  gas  or  common  air ;  the  other  with  a  pneumatic  appar- 
atus to  receive  the  gas ;  by  adding  another  gazometer,  the  gas  may 
be  made  to  pass  repeatedly  back  and  forward. 

(c.)  Diamond,  charcoal,  plumbago  and  anthracite,  or  any  varieties 
of  carbon  may  be  treated  in  the  same  manner,  as  was  done  by  Messrs. 
Allen  and  Pepys,  in  their  celebrated  experiments ;  they  used  a  pla- 
tinum tube  to  contain  the  diamond  and  other  forms  of  carbon,  and 
their  gazometers  were  placed  over  mercury. 

(d.)  Burn  charcoal  in  a  bottle  or  jar  of  oxygen  gas  ;  if  a  piece  of 
well  charred  bark  be  used,  the  combustion  is  attended  with  brilliant 
scintillations  ;  otherwise  with  only  a  bright  glow. 

(e.)  Burn  any  kind  of  wood,  or  a  taper,  in  a  bottle  of  common 
air,  or  of  oxygen  gas,  and  carbonic  acid  will  be  formed,  as  may  be 
evinced  by  the  test  of  lime  water,  which  produces  a  milky  precipi- 
tate. 

(f.)  Diamond  is  easily  made  to  burn  under  the  compound  blow- 
pipe,* and  wastes  entirely  away.  If  the  combustion  be  stopped  in 
its  progress,  the  surface  of  the  diamond  will  be  found,  not  carbonized, 
but  indented  and  dull,  as  if  it  had  been  corroded  and  then  washed. 
In  my  experiments  it  had  the  appearance  of  superficial  fusion. 

(g.)  An  elegant  apparatus  for  the  combustion  of  diamond,  is  fig- 
ured by  Mr.  Brande,  in  his  elements,  and  copied  by  Dr.  Henry,f  by 
which  the  diamond  may  be  burned,  and  the  products  collected.  By 
combustion,  it  is  rapidly  diminished,  and  carbonic  acid  is  abundantly 
precipitated  by  admitting  lime  water. 

(h.)  According  to  the  experiments  of  different  eminent  chem- 
ists, J  28  or  29  grains  of  any  pure  carbon,  require  71  or  72  of  oxy- 
gen and  give  100  carbonic  acid;  201  cubic  inches  of  oxygen  by 
bulk,  require  28  or  29  grains  of  charcoal.  Mr.  Dalton  assumes  the 
composition  of  carbonic  acid  to  be,§  in  round  numbers,  28  carbon  to 


that  diamond  is  carbon,  was  unavoidable.  In  1785,  Guyton  Morveau,  found  that 
the  diamond,  when  dropped  into  melted  nitre,  burns  without  any  residuum,  and  in  a 
manner  analogous  to  charcoal.  Dr.  Tennant  also  burnt  the  diamond  in  nitre,  and 
found  that  carbonic  acid  gas  was  the  only  product. — (Phil.  Trans.  1797.)  Guyton 
Morveau  observed,  that  the  diamond  burns  at  three  different  temperatures,  and  al- 
though some  of  his  conclusions  were  erroneous,  for  instance,  that  the  diamond  can 
be  converted  into  a  substance  resembling  charcoal,  and  that  charcoal  is  an  oxide  of 
carbon,  still  he  fully  established  the  fact  that  diamond  is  by  combustion,  converted 
into  carbonic  acid. 

*  See  Am.  Jour.  Vol.  VI,  p.  349.  t  Vol.  I,  p.  342, 10th  Ed. 

t  Carbon,  28.60;  oxygen,  71.40=100.  Carbon,  27.376;  oxygen,  72.624=100. 
Allen  and  Pepys,  Clement  and  Desormes,  Wollaston,  Gay-Lussac,  and  Berzelius. 
See  Henry,  10th  Ed.  Vol.  I,  p.  344. 

4  The  precise  proportions  appear  to  be  72.72  of  oxygen,  and  27.27  of  carbon, 
which  corresponds  with  2  proportions  of  oxygen  and  of  1  carbon. — Murray. 


CARBONIC  ACID.  367 

72  oxygen,  and  all  the  results  come  so  near  to  this,  that  we  may 
venture  to  neglect  the  fractions.  The  composition  of  carbonic  acid 
is  a  problem  of  great  importance,  for  whenever  it  is  produced,  we 
infer  the  presence  of  carbon  in  the  proportion  now  stated. 

(i.)  Oxygen  gas,  by  uniting  with  charcoal,  suffers  neither  contrac- 
tion nor  expansion,  but  increases-  in  specific  gravity,  so  that  100 
cubic  inches  weigh,  at  the  medium  temperature  and  pressure,  46.59 
grains,  or  about  one  and  a  half  the  weight  of  common  air.* 

These  methods  of  obtaining  carbonic  acid  gas,  are  put  in  practice 
only  to  demonstrate  its  composition ;  they  are  never  resorted  to  when 
the  object  is  to  obtain  the  gas  in  large  quantities  ;  then  it  is  always 
extracted  from  some  of  its  natural  combinations. 

2.  OTHER  MODES  OF  OBTAINING  CARBONIC  ACID  GAS. 

(a.)  Procured  from  marble  poivder,  or  chalk  with  dilute  sulphuric 
or  muriatic  acid.^  The  proportions  with  sulphuric  acid,  may  be 
about  6  parts  by  weight,  of  water,  to  1  acid,  and  1 J  marble  powder  ; 
apparatus — a  retort,  flask,  or  bottle,  with  a  glass  tube,  bent  twice  at 
right  angles,  and  turned  up  at  the  end  of  delivery ;  it  may  be  thrust 
through  a  cork  bored  by  a  tapering  hot  iron  ;  the  residuum  will  be 
sulphate  of  lime. 

(b.)  Heat  marble  powder  or  chalk,  red  hot,  in  an  iron  bottle;  a 
quart  affords  a  barrel  of  gas,  and  the  residuum  is  brought  almost  to 
the  condition  of  quick  lime. 

3.  DECOMPOSITION. 

(a.)  Decomposed  by  repeated  electrical  discharges,  over  mercury; 
becomes  carbonous  oxide, J  and  oxygen  gas. 

The  undecomposed  carbonic  acid,  being  washed  out  by  lime  wa- 
ter, or  potassa,  and  an  electric  discharge  passed  through  the  remain- 
der, it  explodes  and  becomes  again  carbonic  acid. 

(b.)  A  mixture  of  hydrogen  and  carbonic  acid,  being  heated  in 
the  same  manner,  water  and  oxide  of  carbon  are  obtained. 

(c.)  Carbonic  acid,  as  it  exists  in  the  carbonate  of  lime,  and  of 
baryta,  and  probably  strontia,  is  easily  decomposed  by  igniting  the 
pulverized  carbonate  with  iron  filings,  when  oxide  of  carbon  is  pro- 
duced, as  will  be  shewn  in  connexion  with  that  substance. 

(d.)  Potassium  heated  in  carbonic  acid  gas,  in  the  proportion  of 
5  grains  to  3  cubic  inches,  inflames,  and  charcoal  is  precipitated.  || 

*  For  the  statements  of  different  writers,  see  Henry. 

t  Muriatic  acid,  mixed  with  2  or  3  parts  of  water,  is  perhaps  preferable,  be- 
cause the  sulphuric  acid  forms  an  insoluble  compound  with  the  lime,  and  clogs  the 
effervescence. 

t  Whose  propertes  will  be  soon  explained. 

||  I  am  accustomed  to  exhibit  this  beautiful  experiment  by  the  following  arrange- 
ment.— A  flask,  with  dilute  sulphuric  acid  and  marble  powder,  is  fitted  with  a  cork  and 
tube  bent  twice  at  right  angles,  through  which  carbonic  acid  gas  flows  to  the  bottom  of 
another  flask,  and  expels  the  air,  or  the  gas  may  be  introduced  in  a  similar  manner 


368 


CARBONIC  ACID. 


(e.)  Carbonic  acid,  contained  in  carbonate  of  lime,  or  of  soda,  is 
decomposed  by  phosphorus,  and  the  carbon  appears  in  the  form  of 
charcoal. 

(/.)  It  is  done  by  taking  a  glass  tube  J  of  an  inch  wide,  and  20 
inches  long;  it  is  sealed  at  one  end,  and  coated  with  sand  and  clay, 
to  within  an  inch  of  the  end  ;  phosphorus  is  placed  there,  and  mar- 
ble powder,  or  better,  carbonate  of  soda,  dried  in  a  sufficient  heat ; 
the  part  containing  the  carbonate  is  heated  red  hot,  and  then  the 
phosphorus  is  sublimed  through  it,  and  the  heat  continued  for  some 
minutes  ;  charcoal  is  found  mixed  with  a  phosphate.* 

(g.)  In  Dr.  Pearson's  experiment,  200  grains  of  phosphorus,  and 
800  carbonate  of  soda,  gave  40  grains  charcoal. f 

(A.)  If  phosphorus  be  boiled  in  a  solution  of  carbonate  of  soda,  it 
becomes  black  in  consequence  of  the  developement  of  charcoal ;  it 
is  done  in  a  small  flask,  and  the  process  occupies  an  hour. 

4.  PROPERTIES. 

(a.)  Carbonic  acid  gas  is  fatal  to  animal  life  ;  if  we  confine  a 
mouse  or  other  small  animal  in  this  gas,  it  will  speedily  die.  But- 
terflies and  other  insects  may  be  killed  in  this  manner,  or  hy  heat 
alone,  without  injuring  their  beauty.  This  gas  kills  both  by  suffoca- 
tion and  by  a  deadly  influence  of  its  own. 

(b.)  It  extinguishes  combustion ;  lower  a  pendent  candle  into  it, 
and  withdrawing  it  immediately,  drop  it  into  oxygen  gas  ;  it  is  ex- 
tinguished and  relighted  alternately.  Gun  powder  burns  in  this  gas.f 


from  a  small  gazometer.  A  tray  of  platinum,  with  a  lump  of  potassium,  is  slipped 
into  the  flask,  taking  care  at  the  same  time,  not  to  let  in  the  air  or  spill  the  carbon- 
ic acid;  a  tube,  twice  bent  at  right  angles,  is  then  adapted,  and  dips  into  a  glass 
containing  mercury ;  live  coals  are  applied  beneath  the  tray  of  potassium,  and 
just  at  the  point  of  the  fusion  of  plate  glass,  the  potassium 
inflames  with  bright  light,  regenerated  potassa  fills  the 
flask  with  white  fumes,  and  charcoal  precipitates,  mix- 
ed with  the  potassium.  A  green  flask  would  probably  be 
better,  as  enduring  more  heat ;  sometimes  the  experi- 
ment succeeds  with  difficulty,  and  the  bottom  of  the  flask 
is  indented.  N.  B.  The  second  tube  and  the  mercury 
may  be  dispensed  with,  provided  we  cork  the  flask  rath- 
er loosely,  so  as  to  allow  the  gas  to  escape  a  little  by  ex- 
pansion. 

*  Phil.  Trans.  1791,  p.  182. 

t  Phil.  Trans.  1792,  p.  289. 

t  A,  Large  gJass  globe  with  a  wide  neck  filled  with 
carbonic  acid  gas. 

6,  Iron  or  copper  spoon  with  gun  powder  in  it. 

C,  An  iron  rod  heated  red  hot  at  the  lower  end  to  in- 
flame a  few  grains  of  gunpowder. 

d,  Orifice   stopped  with  a  cork,  which   being  with- 
drawn, the  gas  runs  in  a  visible  current  and  fluctuates. 

A  candle  cannot  burn  in  atmospherical  air,  containing 
one  fourth  part,  by  measure,  of  carbonic  acid. 


CARBONIC  ACID. 


369 


(c.)  Mix  smoke  with  this  gas,  by  extinguishing  in  it  a  burning  chip 
or  paper,  or  by  burning  a  cork  with  a  red  hot  iron  borer,  at  the  ves- 
sel's mouth,  or  better  by  exploding  gun  powder  in  a  pendent  spoon, 
in  ajar,  or  globe  filled  with  carbonic  acid ;  see  the  figure  on  p.  368. 

(d.)  The  gas  is  thus  rendered  visible,  and  exhibits  distinct  fluc- 
tuations and  currents. 

(e.)  Butterflies  and  other  insects  of  delicate  colors  are  killed  in  this 
gas,  and  better  than  by  sulphurous  acid  gas.* 

(f.)  By  a  cylindrical  jar,  containing  carbonic  acid  gas  and  a  little 
water,  with  the  aid  of  a  pendent  candle,  we  may  show  the  phenome- 
na of  the  damp  in  wells  and  caverns.  In  the  annexed  apparatus,  two 
ounces  of  the  carbonate  of  am- 
monia, and  half  as  much  deep 
orange  colored  nitrous  acid,  being 
placed  in  the  three  necked  bottle, 
will  evolve  carbonic  acid  gas, 
which  will  thus  be  rendered  visi- 
ble in  its  ascent,  and  in  its  over- 
flow beneath  the  cover  of  the  up- 
per vessel.  This  being  removed 
and  a  candle  introduced,  it  will 
be  extinguished.  The  gas  can 
be  drawn  off  at  A ;  its  current 
will  be  visible,  and  it  will  extin- 
guish a  burning  taper  held  in  its 
course ;  or  it  can  be  drawn  like 
a  liquid  into  any  other  vessel  con- 
taining a  lighted  candle  which  it 
will  thus  put  out.  If  either  ori- 
fice of  the  bottle  be  opened,  all 
the  gas  in  the  upper  vessel  will 
flow  out. — Dr.  Hare.  A  long 
necked  funnel  may  be  substituted 
for  the  upper  vessel. 

(g.)  Sp.  gr.  1.527  ;  100  cub.  inch,  weigh  at  60°  Fahr.  and  30  in. 
Bar.  46.59,  whereas  air  weighs  30.50.f 

(h.)  We  may  pour  the  contents  of  one  jar  into  another,  and  exa- 
mine by  a  pendent  candle  how  high  the  gases  rise. 

(i.)  We  may  collect  it  by  a  bent  tube  passing  into  a  bottle  filled 
only  with  common  air,  which  it  will  expel. 


*  Entomologists  prefer  to  kill  them  simply  by  means  of  heat,  immersing  them  in 
boiling  water,  in  close  vessels. 

t  It  is  said  that  Dr.  Prout  has  recently  ascertained  that  it  is  as  high  at  least  as  31 
grs.     Addenda  to  Turner,  2d  edition. 

47 


370 


CARBONIC  ACID. 


(j.)  The  absorption  of  this  gas  by  water,  is  slow  if  merely  stand- 
ing over  it,  but  rapid,  if  agitated  with  the  water  in  a  bottle. 

(k.)  Noo^s  apparatus  is  an  elegant  one  for  impregnating  water 
with  this  gas  ;  it  combines  agitation  and  moderate  pressure. 

A,  The  pedestal  and  containing  vessel  for  the 
marble  powder  and  acid  ;  «,  an  orifice  for  pouring 
in  the  diluted  acid  which  should  be  mixed  previ- 
ously with  water  and  allowed  to  cool. 

B,  The  neck  of  the  vessel  to  contain  the  water 
which  is  to  be  impregnated  ;  this  neck  contains  a 
glass  cylinder  pierced  longitudinally  with  capillary 
ducts,  and  also  a  plano-convex  lens,  which  oper- 
ates as  a  valve. 

D,  The  containing  vessel  furnished  with  a  stop 
cock  at  C. 

E,  A  vessel  of  retreat  for  the  water.     As  the 
gas  rises  into  the  middle  vessel,  it  causes  the  fluid, 
by  means  of  the  bent  tube  e,  to  mount  into  E,  thus 
producing  hydrostatic  pressure,  and  favoring  the 
combination  of  the  water  with  the  gas. 

Much  more  powerful  instruments  are  known  in 
the  arts.*     The  following  is  from  Dr.  Hare. 

IMPREGNATION  OF  WATER  WITH  CARBONIC  ACID. 


"  A  condenser,  A,  is  fastened   at  bottom,  into  a  block  of  brass, 
which  is  furnished  with  a  conical  brass  screw,  by  means  ol  which,  it 


Phil.  Trans.  1803;  Dr.  Henry's  Apparatus. 


CARBONIC  ACID.  371 

is  easily  attached  firmly  to  the  floor.  In  this  brass  block  are  cavities 
for  the  two  valves,  one  opening  inwards  from  the  pipe,  B,  the  other 
outwards,  towards  the  pipe,  C.  The  pipe,  B,  communicates  with  a 
reservoir  of  gas  which  the  condenser  draws  in,  and  forces  through 
the  other  pipe  into  a  strong  copper  vessel  containing  the  water.  The 
front  part  is  represented  as  removed  in  order  to  expose  the  inside  to 
inspection." 

"  If  due  care  be  taken  to  expel  all  the  air  in  the  vessel  before  the 
impregnation  is  commenced,  the  water  will  take  up  as  many  times  its 
bulk  of  gas,  as  the  pressure  employed  exceeds  that  of  the  atmosphere." 

"  When  duly  saturated,  the  water  may  be  withdrawn  at  pleasure, 
by  means  of  the  syphon,  D,  of  which  one  leg  descends  from  the 
vertex  of  the  vessel,  to  the  bottom,  while  the  other  is  conveniently 
situated  for  filling  a  goblet." 

(Z.)  The  gas  washed  to  free  it  from  any  sulphuric  acid,  and  passed 
up  into  litmus  infusion,  reddens  it  fugaciously. 

(m.)  Liquid*  carbonic  acid  gives  up  its  gas  by  boiling ,  and  by 
being  placed  under  the  exhausted  receiver. 

(n.)  Litmus  water,  reddened  by  this  acid,  is  restored  by  air  pump 
exhaustion,  or  by  boiling. -\  This  gas  is  liberated  from  water  by 
freezing,  which  gives  the  fluid  a  spongy  appearance. 

(o.)  Lime  water  is  a  test  of  carbonic  acid;  it  is  applied  by  pour- 
ing the  liquid  acid  into  it — by  suffering  the  gas  to  pass  into  a  tall  in- 
verted tube  closed  at  the  top  and  filled  with  lime  water,  or  by  re- 
ceiving the  gas  in  a  bottle  and  washing  it  with  lime  water. 

(p.)  An  excess  of  carbonic  acid  redissolves  the  precipitate,  and 
then  more  lime  water  precipitates  it  again,  and  so  on  without  limit. 

(q.)  Burn  a  candle,  a  stick,  or  any  common  combustible,  in  a  bot- 
tle of  air  or  oxygen  gas,  and  examine  by  lime  water  for  carbonic 
acid  ;  if  present  there  will  be  a  milky  precipitate. 

(r.)  Carbon  is  a  principle  of  those  substances  which,  by  burning, 
give  a  gas  not  rapidly  absorbed  by  water,  and  which  precipitates  lime 
water;  the  precipitate  being  soluble  in  muriatic  acid,  with  effervescence. 

(s.)  This  gas  is  an  antiseptic,  and  therefore  useful  in  putrid  dis- 
eases, and  externally  in  ulcers.  Cataplasms  are  made  with  yeast 
and  other  fermenting  materials. 

(t.)  Meat  suspended  in  carbonic  acid,  especially  if  the  gas  be 
frequently  renewed,  keeps  much  longer  than  in  common  air. 

(u.)  Carbonic  acid  promotes  vegetation,  especially  when  in  the 
liquid  form  and  applied  to  the  roots ;  also,  as  an  atmosphere,  pro- 

*  At  a  common  temperature  and  pressure,  water  absorbs  its  own  volume  of  gas  ; 
twice  its  volume  under  a  double  pressure,  and  so  on  in  the  same  ratio. 

t  Tincture  of  alkanet  diluted  and  slightly  blued  by  ammonia,  is  decidedly  redden- 
ed when  agitated  in  a  vial  with  carbonic  acid  gas. 

When  the  above  solution  is  boiled  so  as  to  expel  the  carbonic  acid,  it  resumes  its 
original  blue  color. 


372  CARBONIC  ACID. 

vided  it  does  not  exceed  one  eighth  of  the  whole  ;  beyond  that  it  is 
injurious. 

(v.)  This  gas  exists  in  fermented  liquids  ;  we  may  collect  it  from 
any  fermenting  mixture,  or  from  bottled  cider,  beer,  porter,  &LC.  and 
it  will  prove  to  be  carbonic  acid. 

(iv.)  This  may  be  shewn  by  drawing  the  cork  under  water — the 
mouth  of  the  bottle  being  immersed,  the  gas,  at  least  what  is  spon- 
taneously disengaged,  will  collect  at  top,  and  the  rest  may  be  obtain- 
ed by  boiling  the  fluid  in  a  proper  gas  apparatus. 

5.  MISCELLANEOUS. 

(a.)  Carbonic  acid  gas,  on  account  of  its  gravity,  is  often  found 
at  the  bottom  of  wells  and  caverns,  as  in  the  grotto  Del  Cani,  near 
Naples,  and  thus  often  destroys  those  who  incautiously  descend  into 
them ;  by  letting  down  a  candle,  it  may  always  be  determined 
whether  the  place  is  safe. 

(b.)  Jls  the  combustion  of  charcoal,  and  other  carbonaceous  sub- 
stances, always  generates  carbonic  acid,  it  is  unsafe  ever  to  remain 
in  a  confined  situation,  in  such  an  atmosphere  ;  in  both  these  modes 
many  lives  are  destroyed.  When  it  is  pure,  it  produces  a  spasm  of 
the  glottis,  and  suffocation  ensues ;  if  so  much  diluted  as  to  pass  in- 
to the  lungs,  it  operates  as  a  narcotic  poison.* 

(c.)  There  are  many  other  gases  evolved  in  combustion,  and  all 
of  them  are  deadly  ;  nitrogen  is  always  present  in  such  cases,  and 
frequently  carburetted  hydrogen,  gaseous  oxide  of  carbon,  ammonia, 
and  various  vapors,  as  of  pyroligneous  acid,  &tc. 

(d.)  Fire  should,  therefore,  always  be  made  under  a  good  drawing 
vent. 

(e.)  Carbonic  acid  is  eminently  salutary  in  the  stomach,  although 
fatal  in  the  lungs  ;  witness  the  native  and  artificial  acidulous  waters ; 
its  action  in  the  primae  viae  is  that  of  a  mild  stimulant.  With  com- 
mon air,  it  exists,  dissolved,  in  all  natural  waters,  and  imparts  to 
them  pungency  ;  hence  the  flatness  of  boiled  water,  or  of  that  which 
has  been  exposed  to  air  pump  exhaustion. 

(/.)  Carbonic  acid  gas.  is  the  principal  agent  in  raising  bread  ; 
it  is  generated  in  the  fermenting  mixtures,  as  yeast,  the  sediment  of 
beer,f  &c.,  and  the  native  or  artificial  acidulous  waters  will  inflate 
dough  and  make  it  light. 

(g.)  Carbonic  acid  exists  every  where  in  the  atmosphere  ;  it  was 
found  on  the  top  of  Mount  Blanc,  by  Saussure,J  and  aeronauts 
have  brought  it  down  from  the  greatest  heights  to  which  man  has  as- 

*  It  is  supposed  by  many,  that  charcoal,  when  burning  without  smoke,  is  harm- 
less, and  that  the  anthracite  coal  does  not  produce  a  noxious  gas  ;  both  these  are  very 
dangerous  popular  errors ;  the  deadly  carbonic  acid  gas  is  rapidly  formed  from  both, 
during  the  whole  time  that  they  are  burning. 

t  Called  in  this  country  emptyings.  t  Jour,  de  Phys.  XVII,  p.  202. 


CARBONIC  ACID.  373 

cended ;  in  general,  the  proportion  is  very  uniform.  A  pellicle  is 
formed  on  lime  water,  by  exposure  to  the  air  ;  it  contains  T|¥  carbo- 
nic acid,  as  formerly  stated  ;  according  to  Dalton,  T£T7r,  or  even  less. 

(h.)  Although  produced  in  enormous  quantities  by  respiration, 
combustion,  and  other  processes,  it  is  scarcely  found  to  exist  in  great- 
er proportion  in  large  towns  than  in  the  country  ;  doubtless  the  winds 
prevent  its  accumulation.  At  sea,  however,  only  two  leagues  from 
Dieppe,  there  was  so  little  that  it  scarcely  affected  barytic  water.* 

(i.)  Caustic  alkalies  absorb  carbonic  acid  gas  entirely,  and  thus 
separate  it  from  other  gases. 

(/.)  Vegetation  appears  to  be  the  grand  means  of  preserving  the 
purity  of  the  atmosphere  ;  it  decomposes  the  carbonic  acid,  absorbs 
its  carbon  for  food,  and  lets  loose  its  oxygen. 

It  is  true  that  vegetables  emit  carbonic  acid  in  the  night,  but  in 
smaller  quantity  than  that  which  they  decompose  in  the  day.f 

(k.)  Carbonic  acid  is  visible  in  the  sunshine,  as  it  descends  into  a 
vessel  of  common  air,  because,  on  account  of  its  great  weight,  it  produ- 
ces unequal  refraction  in  the  light,  and  thus  creates  a  disturbed  image. 

6.  RESPIRATION. 

(a.)  About  8  or  8J  per  cent,  of  carbonic  acid  is  thrown  from  the 
human  lungs  in  respiration,  at  every  expiration,  and  only  10  per 
cent,  when  the  contact  is  rendered  almost  as  frequently  as  possible  ; 
a  similar  result  happens  with  the  whole  animal  creation. 

(b.)  About  11  oz.  Troy,  of  carbon,  are  thus  daily  detached  from 
the  blood,  and  of  course  more  than  twice  the  weight  of  a  living  man 
in  a  year. 

(c.)  Thus  one  great  office  of  respiration  is,  the  decarbonization  of 
the  blood. 

(d.)  The  production  of  animal  heat  is  also  intimately  connected 
with  this  process ;  venous  blood  becomes  arterial  in  the  lungs,  and 
there  acquires  its  florid  color,  and  emits  its  excess  of  carbon,  and  its 
capacity  for  heat,  according  to  the  experiments  of  Dr.  Crawford,  J  is 
enlarged  from  .892,  which  expresses  the  capacity  of  venous  blood, 
to  .1030 ;  thus  the  heat  that  would  be  evolved  from  the  union  of  the 
carbon  with  the  oxygen,  is  absorbed,  and  again  given  out  when  the 
arterial  blood  becomes  venous,  that  is,  all  over  the  body.|| 

(e.)  There  can  be  no  doubt  that  animal  heat  is  connected  also  with 
the  nervous  power,  with  secretion,  and  perhaps  with  other  vital  agencies. 

*  Ann.  Phil.  N.  S.  VI,  p.  75.  t  See  Thomson's  Chemistry. 

t  The  experiments  of  Dr.  J.  Davy,  do  not  appear  to  have  set  aside  those  of  Dr. 
Crawford. 

||  In  a  note  on  respiration,  in  Parkes'  Chem.  Chat,  the  following  facts  are  stated. 
The  human  heart  gives  100,000  strokes  in  24  hours,  4000  strokes  in  an  hour,  and 
66  or  67  in  a  minute,  and  350  pounds  of  blood  pass  through  it  in  that  time ;  25 
pounds  is  the  whole  amount  in  the  body  of  a  common  sized  man  ;  this  passes  through 
the  heart  14  times  in  an  hour.  The  aorta  of  a  whale  is  one  foot  in  diameter,  and  10 
or  15  gallons  of  blood  (half  a  barrel,)  are  sent  out  at  every  stroke  with  vast  force. 


374  CARBONIC  ACID. 

(/.)  Lime  or  barytic  water  is  precipitated  by  blowing  through  it 
with  a  tube ;  or  by  agitation  in  air  which  has  been  breathed. 

7.  COMBINING  WEIGHT. — The  weight  of  carbon  is  6,  and  carbonic 
acid  being  a  compound  of  2  proportions  of  oxygen,  and  1  of  carbon, 
its  equivalent  will  be  16-f-6=22. 

In  volumes,  Gay-Lussac  estimates  it  constitution  to  be  1  gaseous 
carbon,  and  1  oxygen,  condensed  into  1  volume.  As  oxygen  under- 
goes no  change  of  volume,  by  combining  with  carbon,  and  as  100  cu- 
bic inches  of  carbonic  acid  weigh  46.597  grains,  it  follows  that  the 
amount  of  carbon  in  vapor  will  be  46.597—33.888,  the  weight  of 
100  cubic  inches  of  oxygen,  =12.709  grs.  of  carbon ;  and  as  12.709 
:  33.888  :  :  6  to  16,  and  6  being  the  combining  proportion  of  car- 
bon, it  follows  that  carbonic  acid  is  composed  as  above.  * 

8.  POLARITY. — Like  other  acids,  it  is  evolved  at  the  positive  pole, 
and  is  therefore  electro  negative. 

9.  LIQUEFACTION  OF  CARBONIC  ACID. 

Mr.  Faraday\  effected  this  by  cold  and  pressure.  He  contrived 
to  extricate  the  carbonic  acid  gas  from  sulphuric  acid  and  carbonate 
of  ammonia,  brought  together  at  the  moment,  and  after  the  bent  glass 
tube  in  which  they  were  contained  was  sealed,  the  other  end  of  the 
tube  was  kept  cold  by  a  freezing  mixture,  and  the  gas,  subjected  to 
its  own  enormous  pressure,  aided  by  cold,  became  fluid.  These  ex- 
periments are  very  hazardous,  as  it  is  a  more  difficult  gas  to  con- 
dense than  any  with  which  Mr.  Faraday  succeeded ;  very  strong 
tubes  were  required  and  yet  they  often  exploded. 

10.  PROPERTIES. 

(a.)  Limpid,  colorless,  very  fluid ;  floating  on  the  other  fluids  in 
the  tube  ;  distils  readily  and  rapidly  between  0  and  32°  ;  refractive 
power  less  than  that  of  water,  not  altered  by  increase  of  cold. 

When  it  was  attempted  to  open  the  tubes,  they  always  burst  with 
powerful  explosions ;  at  32°  the  pressure  was  equal  to  36  atmos- 
pheres. 

Sir  H.  Davy,  in  a  communication  to  the  Royal  Society,  suggested 
the  application  of  condensed  gases  as  a  moving  force,  capable  of  be- 
ing increased  or  diminished  by  slight  variations  of  temperature.  It 
would  be  necessary  only  to  let  loose  a  little  of  the  condensed  carbonic 
acid,  to  produce  a  powerful  movement ;  condensed  nitrogen  would 
be  still  more  powerful,  and  hydrogen  would  exert  a  tremendous  force. 
No  furnaces  would  be  necessary,  but  mere  variations  between  sun- 
shine and  shade  might  perhaps  be  sufficient  to  vary  the  energy  of  the 
power.  It  is  obvious,  however,  that  the  danger  of  explosion  would 
be  great. 

11.  DISCOVERY. — Dr.  Black  discovered  carbonic  acid  in  1755,  or 
6,  and  thus  laid  the  foundations  of  the  pneumatic  chemistry;  he  called 

*  Turner.  t  Phil.  Trans.  1823,  p.  193. 


CARBONATES.  375 

it  fixed  air.*  Its  composition  was  first  demonstrated  in  1772,  by 
Lavoisier,  who,  as  already  stated,  proved  that  the  diamond,  by  being 
burned,  becomes  carbonic  acid  gas. 

12.  NATURAL  ORIGIN. 

Carbonic  acid  gas  is  formed  abundantly  by  the  respiration  of  ani- 
mals; from  our  candles  and  lamps,  and  from  our  fire-places,  and 
from  furnaces,  from  fermentation  and  putrefaction  it  is  perpetually 
rising  into  the  air.  It  forms  nearly  half,  T4/o  j  of  the  beds  and  moun- 
tains of  marble  and  limestone,  and  exists  in  various  other  natural  car- 
bonates, and  abundantly  in  shells.  Its  fatal  prevalence  appears  to  be 
prevented  by  the  fact  that  vegetables  during  their  growth  decompose 
this  gas,  absorbing  its  carbon  for  food,  and  liberating  the  oxygen  to 
recruit  the  waste  of  the  atmosphere. 

The  late  Dr.  Woodhouse,  proved  by  many  experiments,  that  when- 
ever vegetables  emit  oxygen  gas,  it  is  from  the  decomposition  of  car- 
bonic acid  present  in  the  air,  and  dissolved  in  the  waters  which  they 
imbibe.  He  justly  rejected  the  idea  that  they  give  out  oxygen  gas 
of  themselves,  or  from  the  decomposition  of  water. f 

13.  MEDICAL  AND  ECONOMICAL  USES. 

It  is  highly  salutary  in  the  brisk  and  acidulous  natural  mineral  wa- 
ters, such  as  those  of  Saratoga  and  Ballston,  and  in  imitations  of  them 
by  art,  either  with  or  without  saline  substances ;  in  fermented  li- 
quors, to  which  this  agent  imparts  life  and  pungency,  and  in  a  de- 
gree to  all  natural  waters.  It  operates  as  a  tonic,  diuretic  and  an- 
tiseptic remedy.  It  is  said  to  be  very  useful  in  the  hemorrhoids  or 
piles ;  it  is  a  reagent  in  the  laboratory. 

CARBONATES. 

General  facts  and  characters. 

Some  of  them  have  been  long  known,  and  were  used  before  the 
discovery  of  the  power  of  carbonic  acid  to  neutralize  the  alkalies. 

The  carbonates  effervesce  with  acids,  and  emit  carbonic  acid. 
They  are  decomposed  by  heat,  more  or  less  violent ;  the  gas 
being  expelled,   and  the  base  remains.}     Potassa,  soda  and  lithia, 
are  exceptions. 

(c.)  Alkaline  carbonates  turn  the  vegetable  blues  green,  and  have 
an  alkaline  taste. 

(<?.)  They  are  soluble  in  water,  and  the  carbonates  of  the  alkaline 
earths  become  so  by  an  excess  of  carbonic  acid. 

*  The  miners,  alluding  to  its  effect  on  respiration,  call  it  choke  damp. 

t  See  2d  volume  of  Nicholson's  Journal,  8vo.  and  an  abstract  in  Mease's  Domestic 
Encyclopedia. 

t  Charcoal  is  added  to  some  of  the  carbonates  before  ignition,  and  aids  in  produ- 
cing the  effect ;  sometimes  by  decomposing  the  carbonic  acid  itself.  Baryta  and 
strontia  are  usually  managed  in  this  manner. 


it! 


376  CARBONATES. 

(e.)  They  contain  either  one  equivalent  of  acid  to  one  of  base, 
and  are  then  called  carbonates ;  or  two  of  acid  to  one  of  base,  and 
are  then  called  bi-carbonates. 

(/*.)  Most  of  the  carbonates  exist  native,  and  all  may  be  formed 
by  passing  carbonic  acid  gas  through  the  base,  suspended  or  dissolv- 
ed in  water. 


1.  NAME  AND  HISTORY. 

(a.)  In  the  shops  called  salt  of  tartar,  salt  of  wormwood  and  pearl- 
ashes, 

(b.)  The  carbonate  of  potassa  was  always  considered  as  the  pure 
alkali,  till  Dr.  Black  discovered  the  error.f 

(c.)  The  alkalies  as  found  in  the  shops,  under  the  names  of  pearl- 
ashes,  sal  soda  and  volatile  alkali,  have  been  called  sub-carbonates, 
and  when  saturated  with  carbonic  acid  they  were  called  carbonates. 
As  it  is  ascertained  that  in  the  former  state  they  consist  of  one  equiv- 
alent of  alkali  and  one  of  base,  and  in  the  latter  of  two  equivalents 
of  acid  and  one  of  base,  the  last  is  now  called  bi-carbonate  and  the 
first  simply  carbonate. 

2.  PREPARATION. — For  common  purposes  there  is  no  occasion  to 
prepare  this  salt  artificially,  but  for  instruction  or  to  attain  greater 
purity,  it  may  be  done, 

!a.)  By  deflagrating  tartar  with  one  eighth  of  pure  nitre, 
b.)  Tartar  may  be  calcined  in  a  crucible,  which  destroys  the  tar- 
taric  acid  ;  lixiviation  and  evaporation  give  about  one  third  part  of 
dry  carbonate. 

(c.)  Nitre  being  mixed  with  one  fourth  of  dry  powdered  charcoal, 
find  thrown  into  a  red  hot  crucible,  both  acids  are  destroyed,  and  the 
alkali  obtained  amounts  to  rather  less  than  one  half  of  the  nitre  em- 
ployed. J  The  alkali  obtained  from  tartar  may  be  made  to  crystal- 
lize, and  the  crystals  contain  carbonic  acid  22,  1  proportion  ;  potassa 
48,  1  proportion;  water  18,  2  proportions,  =88,  the  equivalent. 

(d.)  Caustic  potash  absorbs  carbonic  acid  gas  with  avidity,  and 
when  saturated,  and  evaporated  to  dryness,  it  forms  the  carbonate  of 
potash,  containing,  according  to  an  average  of  three  analyses,  car- 


*  For  the  natural  history  of  the  carbonate,  see  potassa.  In  vegetables,  it  is  prob- 
ably combined,  for  the  greater  part,  with  acids,  which  being  destroyed  by  the 
fire,  carbonic  acid  is  thus  formed  and  unites  to  the  alkali. 

t  It  has  been  already  mentioned  that  the  old  chemical  books  describe  efferves- 
cence with  acids,  as  a  test  of  alkalies ;  whereas  this  property  belongs  to  their 
carbonates.  Dr.  Black  first  proved  that  this  is  their  common  state,  that  the  carbonic 
acid  greatly  allays  their  acrimony,  and  that  they  are  caustic  only  when  deprived  of  it. 

t  A  little  sulphate  and  muriate  of  potassa,  and  a  little  silica,  are  apt  to  remain  in 
the  alkali  thus  prepared,  and  it  is  difficult  to  remove  them. 


CAROBNATES. 


377 


borne  acid  31.50,  alkali  68.83.  The  ignited  carbonate  contains  no 
water,  but  there  is  in  common  salt  of  tartar  from  twelve  to  sixteen  per 
cent. 

3.  PROPERTIES. 

(a.)  As  it  occurs  in  the  shops,  it  is  never  crystallized  ;  the  pearl- 
ashes  are  always  a  white  porous  mass  ;  the  potashes  are  firm,  and  of 
a  grey,  reddish,  or  dark  color,  and  both  are  impure,  being  mixed, 
usually  with  silica  and  different  salts,  as  the  muriate  and  sulphate  of 
potassa. 

(b.)  Very  deliquescent,  and  in  the  air,  becomes  in  a  few  hours, 
semi-fluid. 

(c.)  Gives  carbonic  acid  gas  by  other  acids  and  by  heat;  alka- 
line to  the  taste,  turns  blue  vegetables  green,  and  is  even  somewhat 
acrimonious,  but  does  not  destroy  the  texture  of  woolen  cloth. 

(d.)  Does  not  absorb  carbonic  acid  from  the  air,  nor  yield  any- 
thing to  alcohol. 

(e.)  Soluble  in  less  than  1  part  of  cold  water,  and  cannot  be  freed 
from  it  without  considerable  heat. 

(/.)   Taste  much  milder  than  that  of  the  caustic  alkalies. 

4.  METHODS  OF  DETERMINING  THE  QUANTITY  OF  REAL  ALKALI. 
(a.)  Potassa  precipitates  alumina  from  alum,  which  its  impurities 

will  not  do  ;  hence,  the  quantity  of  earth  thus  precipitated,  indicates 
the  proportion  of  alkali. 

(b.)  By  nitric  acid,  which  does  not  dissolve  the  impurities  of  the 
salt.* 

(c.)  The  proportion  of  carbonic  acid  indicates  the  proportion  of 
alkali. — In  a  balance,  place  in  one  scale  the  alkali  and  diluted  sul- 
phuric acid,  in  different  vessels ;  counterpoise  them ;  men  add  the 
acid  to  the  alkali ;  the  loss  of  weight  is  carbonic  acid,  and  implies 
about  twice  as  much  alkali. 

(d.)  The  solubility  in  water  is  a  tolerable  criterion. — Most  of  the 
impurities,  especially  sulphate  of  potassa  and  silica,  being  insoluble, 

*    TABLE    BY    VAUQUELIN. 


\ 

1 

Sulphate  of 
Potash. 

Muriate  of 
Potash. 

Insoluble 
Residue. 

II 
|£ 

2* 

as 

1 

Potash  of  Russia,        - 
"          America,            ... 
American  Pearlash,     - 
Potash  of  Treves, 
"           Dantzic,      - 
"            Vosges, 

772 

857 
754 
720 
603 
444 

65 
154 
80 
165 
152 
148 

5 
20 
4 
44 
14 
510 

56 
2 
6 
24 
79 
24 

254 
119 
308 
199 
304 
304 

1152 
1152 
1152 
1152 
1152 
1440 

N.  B.  American  Pearlash  contains  about  65  per  cent,  of  pure  alkali.  —  Thomson 
quoted   from  Ann.  de  Chim.  XI,  293. 

48 


378  CARBONATES. 

or  difficultly  soluble,  the  proportion  of  residuum,  therefore,  indicates 
the  amount  of  impurities.  If  the  impurities  are  soluble,  as  muriate 
of  soda,  then  the  sulphuric  acid  becomes  a  test ;  355  grains  of  this 
acid  of  the  sp.  gr.  1.141,  (which  is  the  best  for  this  purpose,)  satu- 
rate 100  grains  of  carbonate  ofpotassa.  Dissolve  this  in  water,  add 
the  diluted  acid  by  degrees,  till  the  alkali  is  neutralized,  and  weigh 
the  remaining  acid ;  then  as  355  :  100  ::  the  acid  expended  to  the 
proportion  of  alkali.* 

BI-CARBONATE    OF    POTASSA. 

1.  PREPARATION. 

(a.)  In  Nooth's,  or  a  similar  machine,  pass  carbonic  acid  gas, 
to  saturation,  through  a  solution  ofpotassa,  or  of  the  carbonate  in  5 
parts  of  water.  The  bi-carbonate  crystallizes  as  the  process  goes 
forward,  or  afterwards  by  gentle  evaporation. 

(6.)  Or,  we  may  take  If  part  of  carbonate  of  ammonia,  and  4 
of  the  carbonate  of  potassa,  and  dissolve  in  4  of  water ;  distil  with  a 
gentle  heat  in  a  retort ;  ammonia  is  found  in  the  water  of  the  re- 
ceiver, and  bi-carbonate  of  potassa  in  the  retort,  without  any  loss  of 
materials.f 

(c.)  By  exposing  potassa,  or  its  carbonate,  in  the  vats  of  the  brew- 
er, or  of  the  distiller,  we  can  obtain  the  crystallized  bi-carbonate. 

2.  PROPERTIES. 

(a.)  Crystallizes  in  tables,  or  quadrilateral  prisms,  and  is  termi- 
nated by  pyramids. 

(&.)  Taste,  slightly  alkaline,  but  not  caustic  ;  mild  in  the  stomach, 
not  deliquescent. 

(c.)  Sometimes  efflorescent.^ — Sp.  gr.  2.012. 

(d.)  Soluble  at  60°,  in  about  4  parts  of  cold  water,  and  in  about 
5  at  212°.  The  strongest  permanent  solution  at  common  tempe- 
rature, has  the  sp.  gr,  1.54,  and  contains  48.81,  of  carbonate. 

(e.)  Boiling  hot  water  expels  bubbles  of  gas,  amounting  to  ,-\  of 
its  weight.  A  boiling  heat  is  therefore  sufficient  partly  to  decompose 
the  salt. 

(/.)  Decrepitates  and  melts  with  a  gentle  heat,  loses  its  water, 
and  a  red  heat  expels  just  half  its  carbonic  acid,  leaving  it  a  pure 
carbonate. 

3.  PROPORTION  OF  PRINCIPLES. — It  contains  twice  as  much  car- 
bonic acid  as  the  carbonate ;  proved  by  the   quantity  of  gas  given 
out  from  each  by  the  action  of  acids. 


*  Henry,  10th  Ed.  Vol.  1,  p.  544. 

t  To  1  Ib.  of  sub-carbonate  of  potash,  in  solution,  add  2  or  3  oz.  of  carbonate  of  am- 
monia, and  distil. — Dr.  Hope. 

\  During  the  saturation  of  common  pot  or  pearlash,  wilh  carbonic  acid,  silica  is 
always  deposited. 

§  Four.  Vol.  IV,  p.  41. 


CARBONATES,  379 

Acid,  43.9, -f-  base,  47.1,-f-  water,  9.0  =  100. — 2  prop,  carbonic 
acid,  44 -f-  1  potassa,  48, -f  1  water,  9  =  101  for  its  equivalent. 

4.  ACTION  OF  PRECEDING  BODIES. 

(a.)  The  action  of  sulphur  and  of  the  acids,  has  been  already  ex- 
plained. 

(&.)  Decomposed  by  baryta,  strontia,  and  lime,  and  an  earthy  car- 
bonate is  precipitated. 

(c.)  Silica  and  alumina,  by  ignition,  expel  the  acid,  and  unite 
with  the  alkali,  as  before  stated  under  the  manufacture  of  glass. 

(d.)  In  the  humid  way,  decomposes  the  nitrate  and  muriate  of 
baryta,  and  in  the  dry  way,  the  sulphate.  (See  that  salt.) 

5.  USES    OF    THE    CARBONATES    OF    POTASSA. 

Numerous  in  the  arts. — See  potassa. 

In  medicine,  employed  as  an  antacid  and  Uthontriptic,  of  undoubted 
efficacy ;  the  bi-earbonate  in  good  crystals  should  be  preferred ;  it, 
is  dissolved  in  water,  or  in  any  mild  fluid.  When  the  solution  is 
swallowed,  the  gas  is  often  disengaged  by  acid  in  the  stomach,  or  by 
some  mild  vegetable  acid,  taken  for  the  purpose. 

The  crystals  are  often  taken,  a  tea-spoonful  at  once,  or  in  doses 
of  15  to  20  grains,  and  they  operate  actively  as  a  diuretic,  especially 
if  the  solution  is  considerably  diluted.  The  term  super-carbonate, 
formerly  applied  to  this  salt,  is  incorrect.  Dr.  Coxe  justly  remarks, 
that  there  can  be  no  super-carbonate,  except  when  the  solution  is 
highly  charged  with  carbonic  acid  gas,  by  pressure  and  cold. 

The  bi-carbonate  is  one  of  the  most  elegant  of  the  antacid  reme- 
dies ;  it  should  be  in  every  family,  being  perfectly  safe  and  useful 
in  cases  of  disordered  digestion.  With  the  vegetable  acids,  especial- 
ly the  tartaric,  or  citric,  it  forms  a  fine  effervescing  mixture. 

CARBONATE  AND  BI-CARBONATE  OF  SODA. 
CARBONATE. 

1.  NATURAL  HISTORY  AND  ORIGIN. 

Obtained  by  incineration  of  marine  plants,  fee.* 

commerce,  the  impure  soda,  or  carbonate  of  soda,  is  call- 
ed barilla,  or  kelp  ;  it  contains,  besides  this  salt,  sulphate,  muriate, 
and  sulphuret  of  soda,  sulphuret  of  lime,  usually  hydriodate  of  pot- 
assa, and  much  earthy  and  carbonaceous  matter. 


(«.)  01 
(4.)  In 


*  As  already  mentioned  under  soda,  it  is  obtained  from  the  sal  sola  soda  and  kali, 
in  Spain,  the  sal  sola  soda,  and  the  saliccrnia  herbacea,  are  most  esteemed ;  from  the 
fuci  and  other  marine  plants,  in  Scotland  ;  from  lakes  and  spontaneous  efflorescence 
in  Egypt ;  from  veins  in  the  mountains  near  Tripoli,  and  from  the  decomposition  of 
common  salt.  It  effloresces  on  damp  walls,  generally  on  such  as  consist  in  part  of 
lime  and  sea  sand,  the  carbonate  of  lime  and  the  muriate  of  soda  mutually  decom- 
posing each  other. 


380  CARBONATES. 

2.  NAMES. — The  Nitre  of  the  scriptures  is  the  carbonate  of  soda.* 
Anciently  nitrum  or  natron,  and  at  Tripoli,  called  Trona. 

3.  PREPARATION. 

(a.)  Carbonate  of  soda  of  the  shops,  may  be  purified  by  dissolving 
it  in  J  or  £  of  its  weight  of  water. -\ 

(b.)  Effloresced  carbonate  of  soda  is  the  purest,  as  it  thus  sepa- 
rates from  other  salts. 

(c.)  The  solution  is  to  be  evaporated  at  a  loiv  heat,  and  the  crys- 
tals of  muriate  of  soda  skimmed  off,  till  they  cease  to  be  produced, 
and  then  the  solution  may  be  suffered  to  crystallize  by  cooling. f 

4.  PROPERTIES. 

(a.'j  The  crystals  are  decahedra,  composed  of  two  quadrilateral 
pyramids,  united  at  the  bases,  and  truncated  at  their  apices ;  the  pri- 
mary is  an  oblique  rhombic  prism. 

.     (6.)   Taste  is  alkaline  but  not  caustic;  turns  blue  vegetable  colors 
green. 

ic.)  Specific  gravity  1.3591. 
d.)  Soluble  in  2  parts  of  water  at  60°,  and  in  somewhat  less  than 
1  part  at  212°.     As  the  solution  cools  it  deposits  crystals.     The 
strongest  permanent  solution,  at  common  temperature,  has  the  specific 
gravity  1.26. 

(e.)  The  bi-carbonate  ofpotassa  is  scarcely  altered  by  the  air;  the 
carbonate  deliquesces,  but  the  carbonate  of  soda,  on  account  of  its 
large  quantity  of  water  of  crystallization,  (62.69  per  cent.)  effloresces 
rapidly  and  falls  into  powder. 

(f.)  By  being  again  dissolved  in  water,  it  crystallizes  anetv. 

(g.)  Readily  suffers  the  aqueous,  and  by  ignition,  the  real  igneous 
fusion. 

(A.)  By  a  very  violent  heat  most  of  its  carbonic  acid  is  expelled, 
but  not  the  whole. 

5.  PROPORTION  OF  ITS  PRINCIPLES. 

(«.)  By  the  action  of  a  known  and  a  sufficient  weight  of  sulphuric 
acid,  the  quantity  of  carbonic  acid  is  determined,  and  this  action  join- 
ed with  the  effects  of  heat,  has  given  the  following  for  its  composi- 
tion. Acid  13.98,  base  23.33,  water  62.69  =  100.00,  and  omitting 
the  water, 

Acid,       -         -      4 1.23  or  1  proportion  =22 

Soda,     -       -      -  58.77  or  1         «         =32 

100.00  54  and  the  crystals  of 


*  See  p.  251,  (Soda.)  t  Four.  Vol.  IV,  p.  51. 

t  The  calcined  acetate,  dissolved  and  filtered,  and  the  bi-carbonate  heated  in  the 
same  manner,  afford  a  pure  carbonate. 


CARBONATES.  381 


Carbonate  of  soda,    37.5  or  1  proportion  =  54 
Water,       -        -       62.5  or  10      "         =90 


100.  144 

(b.)  100  grains  anhydrous  carbonate  neutralize  460  of  sulphuric 
acid,  density  1.141;  therefore  supposing  no  other  alkali  present,  as 
460  to  the  acid  required  to  saturate  1 00  grains  of  any  sample  of  car- 
bonate of  soda,  : :  100  to  the  quantity  of  anhydrous  carbonate.* 

6.  ACTION  ON  PRECEDING  BODIES. 

Ja.)  All  that  was  said  under  the  preceding  article  is  true  of  this, 
need  not  be  repeated. 

(b.)  Potassa  decomposes  this  salt  and  renders  the  soda  caustic,  just 
as  the  alkaline  earths  act  upon  the  carbonate  of  potassa. 

(c.)  Carbonate  of  soda,  like  carbonate  of  potassa,  by  double  elec- 
tive attraction,  decomposes  many  salts,  even  sulphate  of  baryta,  by 
ignition. 

7.  USES. 

(a.)  Very  valuable  in  the  arts;  in  the  manufacture  of  glass,  es- 
pecially of  the  finer  kinds,  which  it  renders  more  fusible ;  of  hard 
soap  ;  in  dying ;  and  as  a  detergent  in  washing  and  in  bleaching  ;  but 
for  the  two  latter  uses  it  must  be  rendered  caustic. 

(b.)  In  soda  water  it  is  now  extensively  used  as  an  antacid  and 
lithontriptic,  fyc.  and  as  an  agreeable  beverage.  The  watery  solu- 
tion of  the  salt  is  supersaturated  with  carbonic  acid.  It  is  prepared 
in  an  iron  bound  barrel  or  a  strong  copper  vessel  lined  with  tin,  fur- 
nished with  means  of  internal  agitation ;  the  gas  is  injected  by  means 
of  a  forcing  pump  ;  four  or  five  volumes  of  the  gas  are  thus  condensed 
into  one  of  water.  Proportion  of  alkali,  two  ounces  to  ten  pounds  of 
water,  or  from  two  and  a  half  to  three  pounds,  for  a  barrel. 

REMARKS   ON   SODA  WATER. 

Having  been  concerned  in  the  introduction  of  soda  water,  into  this 
country,|  and  having  been  much  conversant  with  its  manufacture 
and  use,  I  may  be  permitted  to  observe — 

(a.)  That  if  properly  prepared,  soda  water  is  a  very  valuable 
thing. — To  this  end,  the  full  proportion  of  soda  should  be  dissolved 
in  ths  water,  and  with  the  aid  of  cold,  agitation  and  pressure,  it 
should  be  made  to  absorb  carbonic  acid  as  much  as  possible.  This 
will  depend  upon  the  strength  of  the  machinery,  and  upon  the  well 
known  law,  that  if,  as  is  the  case  with  the  carbonic  acid  gas,  water, 
at  the  common  atmospheric  pressure,  absorbs  an  equal  volume ;  with 
a  double  pressure  it  will  absorb  two  volumes,  with  a  pressure  again 
doubled,  the  absorption  will  again  be  doubled,  that  is,  it  will  be  four 
times  the  first,  and  so  on. 

*  Henry,  Vol.  I,  p.  565, 10th  ed.  t  March,  1807. 


382  CARBONATES. 


Water  impregnated  with  carbonic  acid  merely,  is  erroneously 
called  soda  water;  it  is  a  pleasant  brisk  acidulous  drink,  and  to  a  de- 
gree useful,  but  it  will  not  remove  acidity ;  it  will  act  feebly  in  cor- 
recting the  alimentary  canal,  and  it  will  have  only  partial  activity  as 
a  diuretic  and  lithontriptic. 

(c.)  If  the  water  contains  only  a  little  carbonate  of  soda,  it  will 
still  fall  far  short  of  the  qualities  of  genuine  soda  water. 

(df.)  It  is  not  sufficient  to  add  the  solution  of  the  salt  at  the  time, 
and  to  draw  the  water  impregnated  with  carbonic  acid  upon  it ;  this 
will  indeed  be  more  useful  than  the  water  named  at  (b)  &c.  but  it 
will  be,  comparatively  vapid,  because  the  alkali  attracts  away  the 
free  carbonic  acid,  which  gives  briskness  to  the  water,  and  the  satur- 
ation which  ought  to  have  been  fully  made  in  the  machine,  is  very 
imperfectly  made  in  the  drinking  glass. 

(e.)  The  genuine  soda  vmter,  with  the  full  charge  of  alkali  and 
gas,  is  an  excellent  antacid,  diuretic,  lithontriptic  and  anti-dyspeptic 
remedy ;  but  much  that  is  called  soda  water,  possesses  these  proper- 
ties only  in  a  very  small  degree. 

(/.)  Soda  water  may  be  used  too  freely. — Large  quantities  of 
water  may  weaken  the  digestion,  and  produce  injury  also  by  the  cold ; 
and  where  the  diuretic  effect  is  needed,  it  is  better  to  repeat  the 
drinking  at  convenient  intervals. 

(g.)  Cordials  and  syrups  mixed  with  the  soda  water,  greatly  im- 
pair or  destroy  its  salutary  effects,  and  may  lead  to  other  bad  results. 

BI-CARBONATE  OF  SODA. 

1.  PREPARATION. 

(a.)  The  saturated  solution  just  described,  or  a  similar  solution 
impregnated  to  saturation  in  any  other  way,  will,  when  gently  evapo- 
rated without  heat,  afford  confused  crystals  of  bi-carbonate. 

(b.)  Or  100  parts  of  the  solution  of  common  carbonate,  mixed 
with  14  of  carbonate  of  ammonia,  distilled,  evaporated  and  crystalliz- 
ed, as  in  the  case  of  carbonate  of  potassa,  will  produce  the  salt. 

(c.)  Exposure  of  the  carbonate,  in  a  brewer's  or  distiller's  vat,  to 
the  action  of  carbonic  acid  gas,  will  spontaneously  effect  the  com- 
bination. 

2.  PROPERTIES. 

a.)  Taste  mild ;  at  60°  soluble  in  9  or  10  parts  of  water. 
b.)   Gentle  heat  expels  part  of  the  gas  and  it  escapes  in  a  vacuum. 
c.)  Effects  the  test  colors,  as  the  sub-carbonate. 
d.)  100  grains,  at  low  ignition,  lose  37.4,  and  62.6  remain  of 
dry  anhydrous  carbonate. 

(e.)  Constitution — carb.  acid,     57.9  or  2  pro.  44 
soda,  42.1  or  1     "    32 

100.  76  its  equivalent. 


CARBONATES.  383 

If  crystallized,  2  proportions  of  water,  18,  will  make  the  equivalent, 
94. 

The  trona  of  Africa  is  said  to  be  a  sesqui-carbonate,*  that  is,  in- 
termediate between  the  carbonate  and  bi-carbonate,  consisting  of 
Carbonic  acid,         39.76  or  3  proportions  =66 
Soda,       -       -        38.55  or  2         "  64 

Water,        -       -    21.69  or  4         "  36 

100.  166  its  equivalent. 

3.  USES. — An  elegant  antacid;  it  is  now  prepared  in  the  large 
way,  and  is  perhaps  preferable,  on  some  accounts,  to  the  bi-carbon- 
ate of  potassa.  It  is  taken  freely ;  the  dose  mentioned  in  the  phar- 
macopoeias is  two  scruples  a  day,  using  the  effloresced  crystals,  which 
will  contain  about  twice  as  much  alkali  as  the  crystals.  It  may  be 
taken  in  powder  or  in  pills.  It  should  be  kept  in  families. 

The  effervescing  draughts  which  are  made  with  what  are  called 
soda  powders  are  not  soda  water ;  the  powders  are  put  up  in  papers ; 
the  blue  paper  contains  half  a  drachm  of  carbonate  of  soda,  and  the 
white  twenty  five  grains  of  tartaric  acid,  which  require  half  a  pint  of 
water ;  the  effervescing  drink  is  a  mixture  of  tartrate  of  soda  and  car- 
bonic acid,  with  perhaps  some  free  alkali.  The  Seidlitz  powders 
have  two  drachms  of  tartarized  soda  and  two  scruples  of  carbonate 
of  soda  in  the  white  paper,  and  thirty  five  grains  of  tartaric  acid  in 
the  blue ;  to  a  solution  of  the  former  in  half  a  pint  of  water  the  latter  is 
added.  These  preparations  are  however  both  useful  and  agreeable. f 

CARBONATES    OF    AMMONIA. 

1.  NAMES,  &c. — In  the  shops,  volatile  salts  or  concrete,  volatile 
alkali,  sal  cornu  cervi,  or  salt  of  hartshorn  ;  volatile  salts,  is  the  name 
most  familiar  to  the  apothecary,  (it  is  now  called  in  chemistry,  sesqui- 
carbonate.) 

2.  PREPARATION,  of  the  salt  of  the  shops. 

(a.)  Obtained  in  the  manufactories,  by  distilling,  in  earthen  or  iron 
retorts — bones,  horns,  or  other  firm  animal  substances."^ 

(b.)  In  pharmacy,  by  heating  dry  chalk,  1  part,  and  dry  muriate 
of  ammonia,  2  parts,  in  an  earthen  retort,  or  one  of  coated  glass ; 
the  sublimed  salt  is  condensed  in  a  cold  receiver. § 

(c.)  Process  of  the  apothecaries. — Muriate  of  ammonia,  1  part, 
and  carbonate  of  lime,  l£,  are  mingled,  100  cwt.  or  more  at  once; 


*  See  Quart.  Jour.  VII.  298,  and  Henry,  Vol.  I,  p.  566,  10th  ed. 

t  Coxe.  t  See  Ammonia,  p.  236. — 10. 

§  It  will  be  seen,  farther  on,  that  the  salt  formed  in  this  manner  has  different  pro- 
portions from  that  which  is  prepared  by  mingling  the  gases  in  equal  volumes ;  the 
latter  is  strictly  the  carbonate.  ^ 


384  CARBONATES. 

an  iron  pot  with  an  earthen  head,  communicating  with  a  cold 
receiver,  usually  a  jug  or  bottle ;  (the  olive  oil  bottles,  after  being 
cleansed,  are  commonly  preferred  ;)  the  carbonate  of  ammonia,  pro- 
duced from  repeated  charges  of  the  materials,  accumulates  by  de- 
grees to  a  thick  crust,  and  the  bottles  are  then  broken  to  extract  it. 
Sometimes  lead  receivers  are  employed,  and  then  the  crust  is  detach- 
ed by  repeated  blows  of  a  wooden  hammer,  applied  to  the  outside.* 

3.  PROPERTIES,  of  the  salt  of  the  shops. 

(#.)  The  crystals  are  so  minute  as  to  be  indistinct ;  they  are  said 
to  be  octahedra  with  truncated  apices. 

(b.)  Volatile,  and  odorous  ;  smell  and  taste  are  like  those  of  pure 
ammonia,  but  weaker.  The  hartshorn  smelling  bottles,  are  lined  with 
this  salt,  whose  odor  is  reviving,  stimulating,  and  refreshing. 

Sc.)  Has  the  usual  alkaline  action  upon  the  test  colors, 
d.)  Soluble  at  60°,  in  less  than  2  parts  of  cold  water ;  and  in  one 
of  hot  water. 

In  boiling  water  volatilized,  and  also  perhaps,  decomposed,  and 
exhaled  in  gas  and  vapor,  with  brisk  ebullition  and  a  strong  ammo- 
niacal  odor. 

(e.)  The  hot  solution  by  rapid  cooling,  crystallizes. f 

(/.)  Not  altered  by  the  air,  but  wastes  rapidly  away. 

(g.)  Evaporates  on  a  hot  iron,  without  melting,  being  more  vapor- 
izable  than  fusible.  Smelling  bottles  are  easily  made  by  heating 
a  portion  of  this  salt  in  a  flask,  whose  neck  is  prolonged  by  a  tube, 
covered  by  an  inverted  empty  vial,  in  which  the  sublimed  salt  will 
be  condensed  and  form  a  crust  or  lining. 

4.  ACTION  OF  THE  PRECEDING  BODIES. 

(a.)  Nearly  the  same  that  has  been  stated  with  respect  to  the  preced- 
ing alkalies  ;  they  and  the  alkaline  earths  attract  its  acid  and  liberate 
the  ammonia,  while  the  acids  attract  the  ammonia  and  liberate  the 
acid  gas  with  effervescence  ;  if  the  acid  is  a  fuming  one,  there  is  a 
white  cloud. 

(b.)  No  action  on  silica,  alumina,  or  zirconia ;  but  dissolves  gluci- 
na  readily.  J 

(c.)  By  double  affinity,  decomposes  various  salts  which  ammonia 
alone  will  not  affect ;  particularly  the  barytic,  strontitic,  and  calcare- 
ous, but  the  carbonic  acid  often  holds  suspended  the  earthy  carbo- 
nate, so  that  it  does  not  precipitate  till  heat  is  applied,  sometimes 
even  to  ebullition. 


*  Dr  Murray's  Lecture  on  Materia  Medica,  March  26,  1806. 
t  Bergman.     Four.  IV.  74. 

I  It  separates  glucina  from  the  other  earths  contained  in  the  beryl  and  emerald  ; 
and  by  evaporation,  it  deposits  the  glucina.     Four.  IV.  75,  and  this  work,  p.  298. 


CARBONATES. 


385 


SESQ.UI    -CARBONATE. 

This  name,  as  already  implied,  has  been  given  to  the  salt  just  de- 
scribed, and  which  is  obtained  by  subliming  1  part  of  muriate  of  am- 
monia, and  1 J  of  dry  carbonate  of  lime  ;  if  no  loss  were  sustained,  it 
should  contain  equal  quantities  of  carbonic  acid,  ammonia,  and  water; 
but  both  ammonia  and  water  are  wasted  by  the  heat,  and  it  in  fact 
consists  of  about  55  acid,  30  base,  and  15  water,  corresponding  very 
nearly  with  the  constitution,  of  acid,  3  proportions,  =66,  base,  2 
=34,  water,  2  =  18=118,  for  its  equivalent.  This  is  Dr.  Henry's 
view,  and  if  correct,  there  seems  to  be  no  occasion,  in  this  case,  for 
a  name  implying  half  a  proportion  ;  for  66  is  obviously  a  multiple  of 
22,  as  34  is  of  17.f 


CARBONATE    OF    AMMONIA. 


1 .  PREPARATION. — There  is  but  one  mode  of  forming  the  carbo- 
nate containing  one  equivalent  of  each  of  the  principles,  and  that  is  by 
mingling  carbonic  acid  gas  I  volume,  and  ammonia  2,  over  mercury  ; 
or  in  a  dry  bottle,  the  gases  coming  from  different  vessels ;  the  solid 
carbonate  is  precipitated,  and  crystallizes  in  plumose  rays  on  the 
interior  of  the  vessels. 

Either  of  the  arrangements  represented  by  the  annexed  figures 
will  answer  very  well  for  this  experiment ;  muriate  of  ammonia  and 
lime  being  in  one  of  the  retorts  or  flasks,  and  marble  powder  and 
diluted  sulphuric  acid  in  the  other.  A  mild  heat  is  applied  to  the 
vessel  containing  the  materials  for  affording  ammonia,  and  the  mid- 
dle vessel  receives  the  condensed  gases. 


2.  COMPOSITION. — Acid,    56.20,  1  proportion,  22 
Alkali,  43.80,  1         "          17 


100.00 
This  salt  is  unknown  in  the  shops. 


39,  its  equivalent. 


*  Sesqui — Latin,  one  and  a  half. 

t  Dr.  Thomson,  who  introduced  the  term  sesqui,  to  provide  for  cases,  where  there 
appears  to  he  half  an  equivalent,  admits  fractions  of  atoms  as  a  provisional  mode  of 
expression,  although,  as  he  distinctly  explains,  from  the  very  nature  of  atoms,  they 
do  not  admit  of  fractions. — First  Principles,  Vol.  I,  p.  32. 

49 


386  CARBONATES. 

BI-CARBONATE. 

1.  PREPARATION,  &c. 

(a.)  Through  a  solution  of  the  carbonate,  in  Nooth's  or  other 
convenient  machine,  pass  a  stream  of  carbonic  acid  gas  to  saturation. 

(b.)  Gentle  evaporation  gives  small  six  sided  prisms,  inodorous  and 
nearly  tasteless. 

(c.)  A  salt  extremely  similar,  appears  to  be  formed,  when  common 
carbonate  of  ammonia  of  the  shops,  is  simply  exposed  in  powder,  to 
the  air ;  it  loses  sometimes  nearly  half  its  weight,  in  a  single  night ; 
the  ammonia  and  perhaps  the  water,  are  more  wasted  than  the  car- 
bonic acid,  and  the  proportion  of  the  latter  is  doubled.  We  may 
often  observe  that  the  volatile  salts  of  the  shops,  when  exposed  to 
the  air,  become  nearly  inodorous  and  their  taste  less  active. 

The  composition,  exclusive  of  water,  is, 

Carb.  acid,  71.81,  2  proportions,  -      44 

Ammonia,    28.19,  1         "  -  17 


100.00  Its  equivalent  61 

"  By  varying  the  proportions  of  the  ingredients  and  the  regulation 
of  the  heat,  it  is  possible  to  obtain  a  bi-carbonate  at  once,  by  subli- 
mation.* 

REMARKS. — The  carbonate  of  ammonia  commonly  used  in  medi- 
cine and  chemistry,  is  that  of  the  shops.  In  medicine,  it  is  a  valua- 
ble remedy  ;  stimulating,  diuretic,  antacid,  anti-poisonous,  &LC.  The 
smelling  bottles  that  have  not  been  exposed  much  to  the  air,  exhale  an 
odor  that  is  highly  stimulating  ;  but  by  careless  keeping  or  frequent 
opening,  they  often  lose  their  activity.  As  a  reagent,  the  carbonate 
of  ammonia  is  very  valuable  in  chemistry  ;  it  is  the  most  convenient 
application,  for  the  removal  of  acid  stains  from  dark  clothes.  It 
should  be  used  in  solution. 

This  is  an  elegant  salt,  composed  entirely  of  condensed  gases ;  its 
elements  are,  for  the  acid,  carbon  and  oxygen  ;  for  the  ammonia, 
hydrogen  and  nitrogen. f  It  is  a  striking  example  of  the  produc- 
tion of  new  properties  by  chemical  combination. 

EARTHY  CARBONATES CARBONATE  OF  LIME. 

I.  NAMES. —  Chalk,  limestone,  marble,  calcareous  spar,  stalactite, 
fyc. — The  natural  carbonate  of  lime,  is  in  these  and  other  forms,  most 
extensively  diffused,  and  contributes  to  many  purposes  of  ornament 
and  utility. 


*  Ann.  of  Philos.  N.  S.  III.  110,  and  Henry,  Vol.  I,  p.  419. 

t  Thus  arranged — carbon  G+2  proportion  of  oxygen,  16  =  22  carb.  acid;  nitrogen, 
14+3  prop.  hyd.  =  17  ammonia,  and  there  arc  two  propor.  of  carb.  acid,  44+1  of  am- 
monia, 17  =  Cl,  as  above. 


CARBONATES.  387 

GENERAL  CHARACTERS  OF  THE  CARBONATES  OF  LIME. 
a.)  Do  not  scintillate,  if  pure. 


(a.) 
(*0 


b.)  Insoluble  in  pure  water. 

c.)  Effervesce  with  acids  generally,  but  unequally.* 

d.)  Become  quick  lime  by  a  strong  heat. 

e.)  Sp.  gr.  under  3.,  generally  not  over  2.7. 

f.)  Every  variety  of  aggregation,  from  compact,  and  even  earthy, 
to  perfect  crystals,  which  are  much  diversified  in  form. 

(g.)  The  crystals  of  all  pure  calcareous  carbonates,  between  600 
and  700  in  number,  have  a  rhomboidal  nucleus,  whose  faces  are 
inclined  at  angles  of  75°  55'  and  105°  5'. 

3.  CHEMICAL  PROPERTIES. 

(a.)  Caloric. — Native  crystallized  carbonate  decrepitates  with 
heat.  Ignition  separates  the  carbonic  acid  gas^  and  the  watery 
vapor,  and  caustic  lime  remains.  By  strong  ignition,  it  loses  .44  or 
.45  in  weight,  about  .44  of  which  is  acid. 

(b.)  That  the  causticity  of  lime  is  owing  to  the  loss  of  carbonic 
acid,  was  discovered  by  Dr.  Black  in  1756. 

(c.)  This  gas  in  contact  with  caustic  lime,  renders  it  again  mild 
and  effervescent,{  and  restores  the  weight  lost  by  the  furnace. 

(d.)  Not  affected  by  air  nor  water. 

(e.)  Soluble  in  liquid  carbonic  acid. — If  saturated  with  the  acid, 
water  dissolves  T  jV  „•  °f  carbonate  of  lime.  Lime  water  is  a  most 
sensible  test  of  carbonic  acid,  producing  a  milky  appearance,  and 
carbonate  of  lime  precipitates ;  but  if  more  carbonated  water  be  ad- 
ded, the  precipitate  is  redissolved,  and  the  fluid  becomes  again  trans- 
parent. 

(/.)  If  the  excess  of  carbonic  acid  be  saturated  by  more  lime 
water,  or  by  ammonia,  the  carbonate  of  lime  is  again  precipitated. 
It  is  precipitated  also  bjr  boiling,  and  by  air  pump  exhaustion. 

(g.)  The  formation  of  stalactites,  and  stalagmites,  and  calcareous 
incrustations  of  various  forms,  in  caverns  and  veins,  and  of  calcare- 
ous petrifactions,  and  the  precipitation  of  the  carbonate  in  a  crys- 
talline or  sub-crystalline  form,  as  the  water  and  gas  evaporate,  de- 
pend upon  the  solution  of  limestone,  by  liquid  carbonic  acid.  In 
limestone  countries,  carbonate  of  lime  is  dissolved  in  the  waters,  usu- 


*  Some  carbonates,  especially  of  earths,  require  to  be  finely  pulverized. 

i  Sir  James  Hall,  by  some  very  ingenious  experiments,  on  carbonate  of  lime,  as 
to  the  effects  of  pressure  in  counteracting  those  of  heat,  succeeded  in  melting  that 
substance,  and  causing  it  to  crystallize  again,  without  losing  its  carbonic  acid.  Edin. 
Trans.  Vol.  VI.  part  I.  Nicholson's  Jour.  Vol.  XIII,  XIV. 

Mr.  Bucholz  also  melted  the  carbonate  of  lime  by  the  sudden  application  of  a  vio- 
lent heat,  without  compression.— Nicholson's  Jour.  XVII,  and  Henry,  Vol.  I,  p. 
588,  10th  Ed. 

t  The  lime  should  be  moist,  or  in  the  state  of  cream  of  lime,  or  least  of  the  hy- 
drate, as  the  gas  is  not  readily  absorbed  by  the  dry  earth. 


388  CARBONATES. 

ally  by  the  agency  of  carbonic  acid,  and  appears  in  the  domestic 
utensils  ;  it  is  deposited  by  boiling,  the  gas  being  thus  expelled.* 

4.  ACTION  or  PRECEDING  BODIES. 

Sa.}  Decomposed  by  acids,  with  effervescence.-^ 
b.)  No  heat  is  evolved  by  acids  acting  on  a  calcareous  carbonate, 
while  with  quick  lime,  there  is  great  heat,  especially  with  sulphuric 
acid.  The  same  is  true  of  potassa,  soda,  and  magnesia,  when  com- 
pared with  their  carbonates.  In  the  cases  in  which  gas  is  evolved, 
the  heat  is  absorbed  to  form  it,  and  thus  becomes  latent,  and  insensi- 
ble ;  the  opposite  will  therefore  be  true  of  the  caustic  substances. 

5.  ESTIMATION  OF  PROPORTIONS. 

(a.)  This  subject  has  occupied  the  attention  of  many  distinguished 
chemists.  The  analyses  of  Dr.  Wollaston,  Prof.  Berzelius,  and  Dr. 
Ure  coincide  so  nearly  in  the  proportions  of  44  acid  and  56  lime, 
that  these  numbers  have  been  adopted  by  Dr.  Henry,  and  they  cor- 
respond with  one  proportion  of  acid,  22,  and  1  of  lime,  28  =  50  for 
the  equivalent. 

(b.)  To  ascertain  the  proportion  of  carbonate  of  lime  in  any  marl 
or  limestone.^ — Effervescence  with  acids  is  generally  regarded  as  a 
proof  of  the  presence  of  a  carbonate  of  lime.  There  are,  however, 
carbonates  of  other  substances,  and  there  are  other  combined  gases, 
besides  carbonic  acid,  that  may  be  disengaged  with  effervescence, 
by  acids ;  but  these  cases  are  so  rare,  and  the  other  so  common, 
that  there  is  little  danger  of  mistake,  especially  when  the  peculiar 
characters  of  the  other  carbonates  are  taken  into  view. 

(c.)  We  must  not  be  deceived  by  the  common  air  lodged  in  the 
pores  of  dry  earthy  bodies ;  when  the  acid  is  added,  this  air  is  ex- 
pelled by  hydrostatic  pressure,  and  exhibits  a  false  effervescence. 
The  matter  should  be  first  immersed  in  water,  and  the  air  thus  ex- 
pelled, and  then  the  acid  may  be  added. 

(d.)  For  an  accurate  result,  place  in  one  scale,  in  a  flask  100  grs. 
of  the  substance,  and  in  a  separate  vessel,  100  of  muriatic  acid,  mix- 
ed with  200  of  water,  and  put  a  counterpoise  to  the  whole  in  the  oppo- 
site scale.  Add  the  diluted  acid,  by  degrees,  till  effervescence  has 
ceased,  and  then  weigh  the  residuum  accurately.  The  loss  of  weight 
is  the  carbonic  acid  ;  therefore,  44  : 100  :  :  the  weight  lost  to  the  pro- 
portion of  carbonate  of  lime,§  granting  that  there  is  no  other  carbon- 


*  The  temporarily  injurious  effects  of  such  waters  upon  the  health  of  strangers 
are  well  known. 

t  Even  vinegar  will,  in  a  degree,  produce  that  effect. 

t  See  Ure's  Diet.  2d  Ed.  p.  297. 

§  Carbonate  of  magnesia  may  be  present. 

From  100  grains  of  carbonate  of  lime,  80  or  90  cubic  inches  of  gas  arc  obtained.  It 
is  a  rich  marl,  that  has  1-4  of  its  weight  of  carbonate  of  lime,  and  sometimes  marls  do 
not  contain  more  than  l-20th.  In  trying  marls,  you  may  reckon  2  1-2  groins  of 


CARBONATES.  389 

ate  present ;  a  complete  solution  indicates  a  pure  carbonate,  proba- 
bly of  lime,  or  of  lime  and  magnesia.* 

(e.)  Expel  the  gas  by  a  red  heat,  and  compare  the  weight  lost  in 
this  trial  and  in  the  other  experiment ;  the  loss  may  be  a  little  great- 
er on  account  of  water.  We  must  also  try  the  residuum  with  an 
acid  to  see  whether  it  effervesces,  and  whether  it  contains  mag- 
nesia.f 

USES. — As  an  antacid ;  in  chalk,  as  a  crayon  ;  in  marble  and  other 
solid  forms,  as  a  building  stone,  valuable  both  for  firmness  and  beau- 
ty ;  to  afford  lime  by  burning,  and  carbonic  acid  for  the  chemists  and 
manufacturers ;  as  a  manure,  both  in  the  form  of  lime  and  of  car- 
bonate of  lime — the  burning  appears  to  be  of  no  use,  except  to  di- 
minish weight  and  cohesion,  so  that  it  may  be  scattered  in  powder 
on  the  land,  where,  if  it  be  quick  lime,  it  reabsorbs  carbonic  acid  and 
water,  and  becomes  again  carbonate  of  lime. 

CARBONATE  OF  BARYTA. 

1.  DISCOVERY. 

(a.)  By  SCHEELE  and  BERGMAN,  but  Dr.  WITHERING, J  first 
found  the  native  mineral  in  1783. 

2.  PREPARATION. — For  demonstrations,  the  native  carbonate  of 
baryta  may  be  used,  but  for  instruction,  a  number  of  processes  may 
be  mentioned. 

(a.)  By  passing  a  current  of  carbonic  acid  gas  through  a  solution 
of  pure  baryta. 

(b.)  By  exposing  the  latter  to  the  air,  when  a  pellicle  of  carbonate 
of  baryta  forms  on  the  surface,  and  being  removed,  another  suc- 
ceeds, and  so  on,  till  the  baryta  is  all  precipitated. 

!c.)  By  mixing  watery  solutions  of  carbonic  acid  and  baryta, 
d.)  By  decomposing,  by  fire,  the  sulphate  of  baryta,  1  part ;  by 
the  carbonate  of  a  fixed  alkali,  2  or  3  parts. 

(e.)  By  any  alkaline  carbonate,  added  to  the  nitrate  or  muriate  of 
baryta. 

(/.)  By  blowing  air  from  the  lungs  through  barytic  water. 


lime  stone,  or  1  1-2  grains  of  lime  for  every  grain  the  marl  loses  by  the  experiment 
of  expelling  the  air.  Vinegar  is  not  sufficiently  strong,  and  it  froths  and  becomes 
clammy,  and  remains  for  several  days  without  permitting  all  the  gas  to  escape. — 
mack's  Lect.  Vol.  II,  p.  120. 

*  The  residuum,  if  any,  should  he  dried,  and  weighed,  and  this  may  correct  the 
former  conclusion. 

t  If  magnesia  be  present,  it  will  be  detected  by  sulphuric  acid,  which  will  form 
a  bitter  soluble  and  crystallizable  sulphate  of  magnesia,  or  Epsom  salt.  Such  a  marl  or 
limestone  would  be  injurious,  if  applied  in  agriculture,  in  quantities  as  large  as 
when  a  pure  calcareous  earth  is  employed  ;  much  less  of  it  answers  the  purpose. — 
Nicholson's  Jour.  4to.  Vol.  Ill,  p.  440,  Phil.  Trans.  1799,  part  II,  p.  305,  and  Bake- 
well's  Geology. 

t  Called  after  him,  Witherite. 


390  CARBONATES. 

(g.)  By  adding  carbonate  of  soda  to  the  hydroguretted  sulphur  et 
of  baryta,  formed  by  decomposing  the  native*  sulphuret,  by  ignition 
with  charcoal,  as  already  described. 

3.  PROPERTIES. 

(a.)  The  artificial  carbonate  is  a  white  powder  whose  specific 
gravity  is  3.763  ;  that  of  the  native,  4.3  or  4.4. 

(b.)  Caloric. — Dr.  Hope  often  expelled  the  carbonic  acid  by 
the  well  managed  heat  of  a  smith's  forge,f  and  obtained  the  caustic 
earth. 

(c.)  Fusible  on  charcoal,  losing  at  the  same  time,  some  of  the  car- 
bonic acid. 

(d.)  MixJ  fine  powder,  of  either  artificial  or  native  carbonate  of 
baryta,  with  about  its  volume  of  lampblack,  and  add  lamp  oil,  until 
the  mass  can  be  rolled  into  a  ball ;  place  it  in  a  black  lead  crucible, 
surrounding  it  with  lampblack  or  charcoal  powder,  and  lute  on  a 
cover ;  heat  the  whole  in  a  good  forge  or  wind  furnace  for  an  hour. 
The  ball  still  retaining  its  form,  may  now  be  taken  out,  and  boiling 
hot  water  added  ;  it  will  slack  powerfully,  and  when  cold,  will  shoot 
into  beautiful  crystals. 

(e.)  Soluble  in  4300  parts  of  water  at  60°,  in  2300  at  212° ;  wa- 
ter impregnated  with  carbonic  acid,  dissolves  with  some  facility  that 
which  has  been  recently  precipitated,  and  takes  up  ¥|^ ;  it  is 
precipitated  and  redissolved  exactly  in  the  same  modes  that  were 
mentioned  under  carbonate  of  lime. 

(/.)   Tasteless — no  effect  on  test  colors. 

(g.)  A  violent  poison,  not  known  in  common  life,  except  in  those 
places  where  it  is  found  native. 

(h.)  Decomposed  by  most  of  the  acids  with  effervescence,  produc- 
ing salts  ;  there  are  some  peculiar  circumstances  which  will  be  men- 
tioned under  the  other  barytic  combinations. 


*  The  native  carbonate  is  found  in  Cumberland,  (England,)  at  Alston  Moor;  in 
Lancashire,  at  Anglezark,  near  Chorley ;  and  in  other  parts  of  England  ;  in  Scotland, 
and  in  Sweden.  It  was  announced,  (Am.  Jour.  Vol.  II,)  as  existing  near  Lexington, 
Kentucky,  but  this  has  not  been  confirmed.  It  is  commonly  found  in  metallic  veins 
along  with  sulphate  of  baryta,  and  various  metallic  substances.  Its  sp.  gr.  is  4.33  or 
4.4,  whence  it  appears  that  it  is  much  heavier  than  the  artificial ;  it  is  a  little  harder 
than  carbonate  of  lime,  but  softer  than  the  fluate. 

t  Dr.  Priestley,  by  steam,  passed  over  the  ignited  artificial  carbonate,  reduced  it 
to  the  state  of  baryta;  in  this  case,  the  attraction  of  the  water  for  the  base,  aids  the 
decomposition. 

t  In  this  process,  the  carbonic  acid  is  not  only  expelled,  but  in  part  decomposed 
by  the  carbon,  which,  with  one  proportion  of  the  oxygen,  produces  carbonic  oxide. 
The  process  I  find  to  be  constantly  successful,  and  it  is  very  eligible  when  we  wish 
to  obtain  either  a  solution  or  crystals  of  baryta.  We  may  begin  with  the  sulphate, 
decompose  it  by  ignition  with  charcoal;  form  the  sulphuretted  hydro-sulphuret ;  de- 
compose this  by  an  alkaline  carbonate,  and  thus  obtain  the  carbonate  of  baryta  for 
this  experiment. 


CARBONATES.  391 

4.  COMPOSITION. — Carbonic  acid, "22,  baryta,  78  =  100,  its  equiv- 
alent. 

5.  MISCELLANEOUS. — Used  for  a  long  time  in  Lancashire,  to  kill 
rats.     With  40  grs.   Mr.  Watt  killed  a  small  dog  5  even  15  grains 
will  produce  that  effect.     It  appears  that  domestic  fowls  are  some- 
times killed  by  swallowing  fragments  of  the  native  spar,  and  that 
even  cows,  by  licking  it,  suffer  the  same  fate.* 

According  to  Dr.  Hope,  there  is  very  little  or  no  difference  be- 
tween lime  and  baryta  in  their  attraction  for  carbonic  acid  ;  lime  wa- 
ter does  not  decompose  carbonate  of  baryta,  nor  the  contrary,  and 
when  carbonic  acid  is  added  to  a  mixture  of  lime  water  and  barytic 
water,  carbonates  of  both  those  substances  are  precipitated. 

6.  USES. — Mr.  Parkesf  states,  that  great  quantities  of  the  carbo- 
nate of  baryta  were  formerly  exported  clandestinely  from  England  to 
Germany,  where  it  is  supposed  it  was  used  in  the  manufacture  of 
porcelain ;  it  was  sold  for  five  dollars  a  ton. 

Carbonate  of  baryta  is  a  rather  rare  production  in  nature.  If  it 
were  more  common,  it  might  be  employed  with  much  advantage  in 
some  of  the  arts — as,  to  afford  baryta,  which,  in  building,  would  form 
a  stronger  cement  than  lime,  and  to  decompose  some  of  the  com- 
pound salts.  Pure  baryta  in  solution,  will  separate  the  carbonic  acid 
entirely  from  a  solution  of  carbonate  of  potassa  or  soda,  and  leave 
the  alkali  caustic.  . 

CARBONATE  OP  STRONTIA. 

1.  DISCOVERY. — Jit  first  confounded  with  the  preceding  ;  the  dif- 
ference suspected  by  Dr.  Crawford,  was  proved  by  Dr.  Hope.J 

2.  PREPARATION. 

(a.)  By  adding  liquid  carbonic  acid  to  a  solution  of  strontia,  the 
precipitate,  is  again  soluble  in  an  excess  of  carbonic  acid,  and  is 
thrown  down  by  more  of  the  earth,  and  so  on  in  the  same  way  as  that 
mentioned  under  the  carbonates  of  lime  and  of  baryta. 

(b.)  By  the  various  methods  already  indicated,  for  the  formation 
of  a  carbonate  of  baryta,  strontia  being  of  course  substituted. 

The  native  carbonate,  although  a  very  rare  production,  is  com- 
monly used  in  laboratories ;  it  is  found  at  Strontian,  in  Argyleshire, 
and  at  Lead  Hills,  in  Scotland,  &c. 

3.  PROPERTIES. 

(a.)  The  native  carbonate  has  ajibrous  and  columnar  texture,  and 
the  cavities  are  usually  lined  with  crystals,  which  are  generally  trans- 
lucent; the  color  is  green  or  greenish  ;  sp.  gr.  3.55  or  3.66  ;  does 
not  fire  with  steel  5  it  is  softer  than  the  fluate,  although  harder  than 


Parkes.  t  Essays,  Vol.  1,  p.  327.  \  Vide  Edin.  Trans.  1793. 


392  CARBONATES. 

the  carbonate  of  lime;  soluble  in  1536  parts  of  boiling  water.     It  is 
insipid. 

(b.)  Fusible  at  226°,  W.  into  a  glass  ;  losing  5  or  6  per  cent,  of 
its  carbonic  acid  ;  in  a  black  lead  crucible,  and  especially  if  mixed 
with  charcoal  and  oil,  the  carbonic  acid  is  wholly  expelled,  and  the 
caustic  earth  remains  ;  this  may  be  done  in  a  smith's  forge  ;  in  a 
strong  fire,  it  fluxes  a  Hessian  crucible  and  produces  a  glass  resemb- 
ling chrysolite. 

!c.)  Air  does  not  affect  it. 
d.)  Decomposed  by  the  acids,  with  effervescence. 

4.  COMPOSITION. — According  to  the  analysis  of  Stromeyer,*  the 
artificial  carbonate  contains  no  water,  and  has  very  nearly  .30  car- 
bonic acid,  and  .70  strontia. 

The  equivalent  of  strontia,  is  52,  that  of  carbonic  acid,  22,  and  as 
22  J  52  : :  70  :  30,  very  nearly  ;  so  that  the  theoretical  constitution 
agrees  almost  with  the  results  of  analysis. 

5.  MISCELLANEOUS. 

(a.)  Strontia  takes  the  carbonic  acid  from  all  the  alkalies  ;  its  car- 
bonate, with  the  aid  of  heat,  is  decomposed  by  baryta  only  ;f  still  it 
is  uncertain  which  of  the  alkaline  earths  has  the  stronger  attraction 
for  carbonic  acid.J  Distinguished  from  carbonate  of  baryta,  by  an 
inferior  sp.  gr.  by  the  fact  that  its  salts  yield  their  acids  to  baryta, 
and  that  it  is  not  poisonous  ;  animals  may  take  it  with  impunity  ;  its 
nitrate  tinges  the  flame  of  a  candle  red  ;  that  of  baryta  tinges  it  yel- 
low; under  the  compound  blowpipe,  all  its  varieties  give  a  red 
flame,  and  all  those  of  baryta  a  yellow  one.  It  has  never  been  intro- 
duced into  medicine,  and  is  of  no  use  except  to  chemists. 

CARBONATE  OF  MAGNESIA. 

1.  HISTORY. — Long  known,  but  not  well   understood  till   Dr. 
Black  gave  its  true  theory,  as  well  as  that  of  lime  and  the  alkalies.^ 

2.  PREPARATION. 

(a.)  By  slowly  dissolving  pure  magnesia  in  liquid  carbonic  acid.\\ 


*  Ann.  de  Chim.  et  de  Phys.  Ill,  396. 

t  Four.  IV,  22.  t  Dr.  Hope. 

§  Every  student  should  read  Dr.  Black's  own  account  of  the  gradual  developement 
of  this  curious  and  instructive  subject — namely,  the  relation  of  carbonic  acid  to  the 
alkaline  substances  ;  it  is  a  fine  example  of  inductive  reasoning,  and  has  contributed 
more  than  any  other  thing  to  the  progress  of  pneumatic  chemistry.  See  Robison's 
Black's  Lectures. 

||  A  native  carbonate  of  magnesia  has  been  found  in  the  East  Indies,  and  analyzed 
by  Dr.  Henry,  Ann.  of  Philos.  N.  S.  I,  252.  Native  carbonates  have  been  found  at 
Hoboken,  near  New  York,  Am.  Jour.  Vol.  I.  Calcined  or  pure  magnesia,  unlike 
the  alkalies  and  the  other  alkaline  earths,  does  not  absorb  much  carbonic  acid  from 
the  air,  and  consequently,  it  acquires  little  weight  except  from  the  absorption  of  wa- 
ter, which  makes  it  a  hydrate,  and  it  afterwards  acquires  some  carbonic  acid. 


CARBONATES.  393 

(b.)  By  decomposing  the  sulphate  of  magnesia,  by  the  carbonate  of 
an  alkali. — The  sulphate,  1  part,  dissolved  in  2  parts  of  pure  water  ; 
and  1  part  of  pearl  ashes,  dissolved  in  4  or  5  parts  of  water.* 

Dr.  Blacks  process.-^- Mix  the  two  solutions  by  violent  agitation, 
and  let  the  mixture  merely  boil;  add  four  parts  of  water,  at  212°, 
and  again  agitate  briskly.  After  repose,  the  magnesia  subsides  very 
slowly,  in  the  form  of  an  impalpable  powder  ;  next  decant,  and  to 
remove  the  sulphate  of  potassa,  edulcorate  ten  or  twelve  times  with 
abundance  of  cold  water,  f 

Lastly,  the  magnesia  must  be  gently  pressed  on  a  clean  linen 
cloth,  for  the  filtering  papers  will  not  do,  on  account  of  the  jelly- 
like  consistency,  which  magnesia,  when  wet,  assumes.  It  is  divided 
into  cubical  pieces,  by  cutting  it  before  it  is  quite  dry,  with  a  square 
frame ;  but  when  dried,  it  becomes  an  exceedingly  light  and  spon- 
gy powder,  and  this  extreme  lightness  is  one  of  the  best  marks  of  its 
goodness.J 

In  decomposing  the  sulphate  of  magnesia  with  the  carbonate  of 
potassa,^  or  other  alkaline  carbonates ;  the  precipitate  does  not  al- 
ways immediately  appear,  because  the  carbonate  of  magnesia  is  held 
in  solution  by  the  carbonic  acid,  and  is  precipitated  as  fast  as  this  is 
evaporated,  spontaneously  or  by  heat,  or  by  the  air  pump. 

3.  PROPERTIES. 

(a.)  A  mild,  white,  friable,  spongy  substance,  very  light,  but  usu- 
ally feebly  cohering  in  a  sort  of  cake,  generally  so  light  on  account 
of  its  porosity,  as  to  float  on  water ;  but  it  eventually  absorbs  so 
much  as  to  sink. 

(b.)  Solubility  in  water  ;  1  part  of  carbonate  of  magnesia,  in  2493 
parts  of  cold,  and  9000  of  hot  water,  presenting  a  singular  anomaly, 
which  is  doubtless  owing  to  the  additional  elasticity  given  to  the  car- 
bonic acid  by  the  heat,  and  the  hotter  the  water  is,  the  more  carbonic 
acid  is  expelled,  and  the  more  insoluble  the  carbonate  becomes. 

(c.)  This  solution  changes  the  color  of  purple  cabbage  or  mallows, 
to  green. 

(d.)  Suffers  no  change  from  the  air. 


*  These  are  clarified  by  subsidence  and  decantation,  and  the  Epsom  salt,  by  agita- 
ting in  it  the  white  of  an  egg,  when  the  solution  is  just  warm  enough  to  produce 
coagulation. 

t  Hot  water  occasions  a  much  longer  suspension  of  the  magnesia. 

t  The  theory  which  Dr.  Black  was  establishing  concerning  the  combined  state 
of  carbonic  acid,  made  him  peculiarly  nice  in  the  preparation  of  magnesia.  Black, 
II,  57,  and  Dr.  Murray's  private  instructions. 

§  As  the  common  pearl  ashes  often  contains  silica,  the  magnesia  may  be  examined1 
by  sulphuric  acid,  in  which,  if  pure,  it  is  entirely  soluble,  while  the  silica  will  be 
left  behind.  If  the  carbonate  of  ammonia  or  of  soda,  were  employed,  there  would 
be  no  danger  of  the  presence  of  silica,  and  the  bi-cavbonate  of  potassa  would  not  coa- 
tain  it. 

50 


394  CARBONATES, 

(e.)  Decomposed  by  all  the  acids,  with  effervescence. 

(f.)  Also  by  all  the  alkaline  bases,  forming  carbonates ;  and  in 
turn  decomposes  their  salts,  by  do'uble  attraction. 

(g.)  Lime  water  and  carbonate  of  magnesia  produce  a  mixed  pre- 
cipitate of  the  two  carbonates. 

4.  COMPOSITION. — According  to  Bucholz,  if  precipitated  with 
heat,  it  contains  magnesia  42,  carbonic  acid  35,  water  23;  if  with- 
out, magnesia  33,  carbonic  acid  32,  water  35.  Mr.  Dalton  states  it 
at  magnesia  43,  carbonic  acid  40,  water  17.  Berzelius  thinks  that  it 
is  a  compound  of  carbonate  of  magnesia,  3  proportions,  with  one  of 
what  is  called  quadro-hydrate  of  the  same  earth.  Dr.  Henry  in- 
clines to  the  same  opinion,  and  states  the  composition  thus ; 

3  equivalents  of  carbonate,  42x3   =126        69.2 

1          do.  quadro-hydrate,     20+36=   56        30.8 

Its  equivalent,          182      100.0 
Or  of  magnesia  in  the  carbonate,     -       -      32.93  )  .„  Qc> 

Do.  in  the  hydrate,     -      -      -11.00$- 

Carbonic  acid,       -  -       36.32 

Water,     -  -       -     19.75 

100.00 

Berzelius  found  the  common  magnesia  of  the  shops,  after  being  thor- 
oughly washed  in  boiling  hot  water,  to  be  composed  of  magnesia 
44.58,  carbonic  acid  35.70,  water  19.72  =  100.00. 

CRYSTALLIZED  CARBONATE   OF  MAGNESIA. 

\ 

1.  PROCESS. — By  diffusing  magnesia  in  water,  and  passing  a  cur- 
rent of  carbonic  acid  gas  through  it  to  saturation. 

2.  PROPERTIES. 

(a.)  Much  more  soluble  than  the  carbonate,  requiring  only  48 
parts  of  cold  water,  and  water  impregnated  with  carbonic  acid  takes 
up  13  grains  to  the  ounce. 

(b.)  When  the  solution  is  heated,  although  transparent  before,  it 
becomes  turbid,  and  again  resumes  its  transparency  on  becoming  cold.f 

(c.)  It  crystallizes,  in  transparent  hexagonal  prisms,  terminated  by 
a  hexagonal  plane  ;  partly  in  groups  and  partly  solitary ;  length  about 
6  lines,  and  breadth  2. 

(d.)  Effloresces  in  the  air,  and  decrepitates  in  the  fire ;  it  loses 
about  .75  of  its  weight,  while  the  common  carbonate  loses  only  .50. 

*  Thomson's  First  Principles,  Vol.  II,  p.  303,  and  Henry,  10th  ed.  Vol.  I,  p.  617. 

t  The  heat  must  be  discontinued  just  at  the  point  where  the  solution  becomes  tur- 
bid, or  the  carbonic  acid  will  be  driven  off.  The  reason  of  this  turbidness  is  sup- 
posed to  be  the  elasticity  of  the  gas,  tending  to  escape,  and  thereby  beginning  to 
let  go  its  hold  on  tho  magnesia. — Dr.  Hope,  Note  Book. 


CARBONIC  OXIDE.  395 

(e.)  During  the  disengagement  of  the  gas,  die  powder  seems  as  if 
boiling,  and  is  said  to  emit,  towards  the  end,  a  bluish  phosphoric  light.* 

Remark. — The  above  described  salt  has  been  regarded  as  a  bi- 
carbonate, but  Dr.  Henry  is  of  opinion,  from  his  own  analysis  and 
from  that  of  Berzelius,  that  it  is  a  hydrated  carbonate  and  that  its 
composition  is 

1  equivalent  of  magnesia,  -  20         28.60 

1          do.  carbonic  acid,        -         -       22         32. 

3         do.  water,     -  27         39.40 

Its  equivalent  69        100.00 

It  appears  that,   although  the  anhydrous  carbonate  has  been  found 
native,  (see  note  p.  392,)  it  has  not  yet  been  formed  by  art. 

Berzelius  has  formed  a  carbonate  of  magnesia  and  potassa,  by 
mingling  bi-carbonate  of  potassa  and  muriate  of  magnesia.  It  seems 
to  be  of  little  importance,  f 

3.  MISCELLANEOUS. ~/w  the  arts,  the  carbonate  of  magnesia  is  pre- 
pared from  the  bittern  of  the  salt  pans,  remaining  from  the  crystalli- 
zation of  common  salt,  which  contains  much  muriate  and  sulphate  of 
magnesia.     Carbonate  of  either  of  the  alkalies,  by  double  exchange, 
affords  carbonate  of  magnesia,  whose  precipitation  is  hastened  by 
boiling. 

4.  USES. — As  an  antacid  and  cathartic.  (See  magnesia,  p.  273.) 
On  account  of  the  flatulency  sometimes  produced  by  the  carbonate 
of  magnesia,   calcined  magnesia  is  used.     Dr.  Black  says  that  it 
is  liable  to  contain  a  portion  of  quick  lime,   derived  from  the  sul- 
phate of  lime  of  the  bittern.     No  other  earth  has  cathartic  powers ; 
most  of  the  rest  are  austere  and  astringent,  particularly  lime. 

CARBONIC  OR  CARBONOUS  OXIDE. 

1.  HISTORY. — Discovered  by  Dr.  Priestley;  who  obtained  it 
from  dry  metallic  oxides  with  dry  charcoal,  and  thought  it  was,  at 
least  in  part,  hydrogen,  or  that  hydrogen  entered  into  its  composi- 
tion ;  it  therefore  revived,  for  a  season,  the  once  favorite  notion  of  a 
phlogistic  f  principle  in  the  metals,  charcoal,  &c.  and  an  animated  con- 

*  Four.  IV.  67.  t  Edin.  Phil.  Jour.  II.  67,  and  Henry,  I.  619. 

t  I  happened  to  be  in  Philadelphia,  as  a  pupil  of  Dr.  Woodhouse,  in  the  winter  of 
1802-3,  when  Dr.  Priestley,  who,  as  is  well  known,  passed  the  latter  years  of  his  life 
in  Pennsylvania,  came  in  person,  to  the  laboratory  of  Dr.  Woodhouse,  who  was 
himself  a  disciple  of  Lavoisier,  and  who  performed  various  experiments  on  this  topic, 
at  that  time  keenly  controverted.  It  was  the  last  effort  to  sustain  the  doctrine  of 
phlogiston,  and  to  produce  from  metals  and  inflammables  a  real  substance,  to  which 
it  was  supposed  that  the  name  of  phlogiston  could  be  applied.  Hydrogen  had  been 
before  called  phlogiston,  but  it  was  impossible  to  prove  its  existence  in  all  inflammable 
bodies  and  metals,  (unless  the  discovery  of  this  gas  should  establish  it,)  and  it  was 
distinctly  proved  that  it  forms  water  by  its  combustion.  Indeed  Dr.  Priestley  was 
one  of  the  first  to  perform  that  interesting  experiment,  but  he  did  not  eventually  ad- 
mit the  conclusion. 


396  CARBONIC  OXIDE. 

troversy  respecting  it  was  for  some  time  maintained,  but  its  true  na- 
ture was  soon  pointed  out,  by  the  late  Mr.  Cruickshanks,  of  Wool- 
wich, England  ;*  Clement  and  Desormesf  completed  the  demon- 
stration, and  the  refutation  of  the  ideas  of  the  associated  Dutch 
chemists  and  others,  who  took  it  for  a  variety  of  carburetted  hydro- 
gen gas-t 

2.  PREPARATION. — All  the  processes  mentioned  below,  are  in- 
structive. They  all  shew,  (that  under  (g)  excepted,)  the  formation  of 
an  oxide  of  carbon,  either  by  the  combination  of  1  equivalent  of  oxy- 
gen with  1  of  carbon,  or  by  the  removal  of  1  equivalent  of  oxygen 
from  carbonic  acid,  leaving  1  of  carbon  and  1  of  oxygen  in  combina- 
tion. To  the  former  belong  the  processes  (a)  (e),  and  (/.)  to  the 
latter  (6),  (c),  and  (d)  ;  (g)  is  peculiar. 

(a.)  Heat  white  oxide  of  zinc  with  J  of  charcoal  powder  or  iron 
filings; 

(6.)  Or  iron  filings  with  an  equal  weight  of  chalk,  previously  heat- 
ed moderately  red. 

(c.)  Or  dry  carbonate  of  lime  or  of  baryta^  with  }  charcoal  pow- 
der, previously  ignited;  or  heat  the  same  carbonates  with  J  or  J  of 
dry  iron  filings  or  metallic  zinc. 

(d.)  Bypassing  carbonic  acid  over  charcoal  or  iron  filings,  ignited 
in  an  earthen  or  perhaps  iron  tube.|| 

(e.)  Heat  equal  parts  of  the  scales  of  iron  with  dried  charcoal 
powder. 

(jf.)  Manganese,  after  ceasing  to  give  oxygen  by  heat  alone,  mix- 
ed with  an  equal  weight  of  charcoal,  previously  ignited. IF 

(g.)  Still  another  process  has  been  introduced,  by  mixing  salt  of 
sorrel  1  part  (bin-oxalate  of  potash)  with  5  or  6  of  sulphuric  acid, 
and  heating  the  mixture  to  ebullition  in  a  retort ;  decomposition  of 
the  oxalic  acid  ensues,  and  carbonic  acid  and  carbonic  oxide  are 
evolved  in  equal  measures  ;  the  former  is  easily  absorbed  by  a  caustic 
alkali  or  by  lime  water,  and  leaves  the  latter  pure.  The  sulphuric 
acid  is  not  decomposed  ;  it  remains  limpid,  and  operates  by  uniting 

*  Nich.  Jour.  4to,  Vol.  V.  t  Ann.  de  Chim.  Vol.  XXXIX. 

t  Ann.  de  Chim.  XXXIX,  26,  and  XLIII. 

§  The  dry  carbonate  of  baryta  and  dry  iron  filings  give  the  purest  gas,  and  nearly 
free  from  carbonic  acid.  The  process  with  oxide  of  zinc  and  iron  filings,  is  one  ol* 
the  best,  and  affords  abundance  of  gas  which  is  easily  purified  by  washing  it  with 
caustic  alkali  or  lime  water. 

||  See  Nich.  Jour.  Vol.  II,  p.  116,  for  BarueFs  apparatus. 

IT  Any  carbonate,  that  will  sustain  ignition,  without  decomposition,  will  give  car- 
bonic oxide,  if  heated  with  half  its  weight  of  iron  filings  or  charcoal ;  iron  is  of 
course,  oxidized  by  the  oxygen  withdrawn  from  the  carbonic  acid  which  undergoes 
decomposition,  giving  up  just  half  its  oxygen;  and  charcoal  is  turned  into  carbonic 
oxide  by  the  same  process.  The  carbonates  of  strontia,  soda,  potassa  and  lithia, 
utay  be  employed  in  addition  to  those  that  have  been  named,  and  the  oxide  of  lead 
aad  copper  may  be  used  with  charcoal,  as  well  as  the  oxide  of  zinc  or  iron. 


CARBONIC  OXIDE.  397 

with  the  alkali  of  the  salt  and  with  the  water  of  the  oxalic  acid, 
which  being  thus  left  at  liberty,  is  decomposed  as  above. * 

3.  PROPERTIES. 

(a.)  Smell  offensive;  colorless;  sp.  gr.  972,  common  air  being 
1000.  100  cubic  inches  weigh  29.65  grains,  at  medium  tempera- 
ture and  pressure ;  having  the  same  weight  as  nitrogen. 

(b.)  Does  not  support  combustion;  a  candle  will  not  burn  in  it. 
Inflammable,  burning  with  a  blue  flame;  it  takes  fire  at  a  low  tem- 
perature, and  an  iron  wire,  at  dull  redness,  kindles  it ;  w^hile  the  hy- 
drogen gases  require  a  full  ignition  or  a  white  heat. 

(c.)  It  must  be  washed  with  lime  water,  or  passed  through  milk  of 
lime  or  caustic  alkali,  as  it  always  comes  over  with  carbonic  acid  gas. 

(d.)  Burn,  in  a  bottle  of  air,  a  jet  of  this  gas,  issuing  from  a  jar 
with  a  stop  cock,  and  it  will  form  carbonic  acid.-^ 

(e.)  Mixed  with  common  air,  it  burns  more  rapidly,  but  does  not 
explode,  except  in  a  few  proportions,  as  3  of  the  oxide  gas  to  1  of  air. 

(/.)  With  oxygen  gas  100  volumes  and  this  gas  about  200,  it  ex- 
plodes by  electricity,  and  the  product  is  200  of  carbonic  acid  ;  the  two 
gases  being  mixed  in  the  above  proportions,  when  a  candle  is  brought 
to  the  mouth  of  the  vessel,  burn  rapidly,  with  a  whistling  noise,  but 
scarcely  explode. 

(g.)  Fire  a  jet  of  it  and  burn  it  in  a  tube,  when  it  will  produce 
feeble  musical  tones ;  and  if  burnt  in  a  bottle  of  oxygen  gas,  over 
lime  water,  no  water  is  formed  but  carbonic  acid  is  produced. 

(h.)  It  is  well  to  burn  and  explode  some  hydrogen,  and  also  varie- 
ties of  carburetted  hydrogen,  for  comparison  with  this  gas,  when  it 
will  be  seen  to  be  very  different ;  it  is  less  combustible,  burns  with  a 
different  flame  and  produces  carbonic  acid  only,  without  water,  while 
the  former  produces  water  only,  and  the  latter  both  water  and  car- 
bonic acid.  The  formation  of  water  in  this  experiment,  is  owing 
to  the  hydrogen,  and  that  of  carbonic  acid  to  the  carbon  contained 
in  the  gas. 


*  Edin.  Jour,  of  Sci.  No.  xii,  p.  350.     Turner  and  Dumas. 

t  The  carburetted  hydrogen  gases  require  iron  in  actual  combustion,  or 
the  flame  of  some  burning  body,  in  order  to  set  them  on  fire. 

t  When  this  gas  is  burned  in  a  bottle  of  common  air,  by  means  of  ajar 
with  a  stop  cock  and  tube,  as  in  the  annexed  figure,  no  water  is  formed  ; 
but  it  is  otherwise  when  hydrogen  is  burned. 

A.  Jar  of  common  air. 

B.  Jar  with  a  stop  cock  and  tube,  containing  the  gas. 


398  CARBONIC  OXIDE. 

(i.)  It  is  immediately  fatal  to  animal  life;  a  bird  put  into  it  is  not 
withdrawn  alive. 

(j.)  It  produces  giddiness  and  fainting  in  the  human  subject,  even 
when  mixed  with  common  air.     Sir  H.  Davy  was  so  daring  as  to  take 
three  inspirations  of  it,  mixed  with  J  of  common  air,  and  it  had  near- 
ly proved  fatal ;  apoplectic  symptoms  were  induced  in  Mr.  Welter, 
who  fell  senseless,  but  was  restored  by  inhaling  oxygen  gas.* 
k.)  But  little  soluble  in  water;  about  1  volume  to  50. 
I.)  Not  absorbed  by  caustic  alkalies,  nor  by  lime  water. 
m.)  Not  altered  by  electricity. 

n.)  Passed  in  equal  volume  with  hydrogen,  through  an  ignited 
tube,  it  is  decomposed,  water  is  formed  and  charcoal  thrown  down, 
lining  the  tube. 

(o.)  Potassium  and  sodium,  heated  in  it,  decompose  it,  and  pre- 
cipitate the  charcoal. 
4.  COMPOSITION. 

(a.)  43  carbon,  57  oxygen,  (Gay  Lussac  ;)  or  55.72  oxygen  and 
44.28  charcoal,  (Berzelius.)f  Carbonic  acid  is  composed  of  1  vol- 
ume of  gaseous  carbon  and  1  of  oxygen  condensed  into  1  volume. 
This  gas  is  composed  of  1  volume  of  gaseous  carbon  and  half  a  vol- 
ume of  oxygen,  condensed  into  1  volume ;  or  of  1  equivalent  of 
carbon  =6-}-l  of  oxygen  J  =8  =  14,  for  its  equivalent.  As  it  con- 
tains just  the  same  quantity  of  carbon  as  carbonic  acid,  occupies  the 
same  volume,  and  has  only  half  as  much  oxygen,  therefore,  if  from 
the  specific  gravity  of  carbonic  acid,  which  is  1.527,  we  take  0.555, 
which  is  half  the  sp.  gr.  of  oxygen,  we  have  0.972,  the  number 
stated  under  3  (a),  which  corresponds  with  the  results  of  experiment. 
(6.)  The  discovery  of  the  singular  agencies  of  spongy  platinum, 
has  brought  to  light  some  new  facts  respecting  oxide  of  carbon.  Car- 
bonic oxide,  with  more  than  half  its  volume  of  oxygen,  in  contact 
with  spongy  platinum,  over  mercury,  begins  to  be  converted  into 
carbonic  acid,  at  a  temperature  from  300°  to  310°  Fahr.  and  at  a 
few  degrees  higher  is  acidified  in  a  few  minutes ;  at  a  common  tem- 
perature there  is  little  action. 

(c.)  Hydrogen  and  oxygen  gases,  in  explosive  proportions,  mixed 
with  an  equal  volume  of  carbonic  oxide,  do  not  detonate,  when  spon- 
gy platinum  is  added,  but  water  and  carbonic  acid  are  slowly  formed ; 
if  the  proportion  of  the  explosive  mixture  be  larger,  the  metallic 
sponge  always  causes  detonation.^ 


*  Phil.  Mag.  V.  43.     Ure,  2d  ed.  299. 

t  And  Clement  and  Desormes,  nearly  the  same  as  Berzelius. 

i  As  half  a  volume  of  oxygen  represents  an  equivalent. 

§  Phil.  Trans.  1824,  p.  271,  quoted  by  Dr.  Henry,  Vol.  I,  p.  355,  10th  ed. 


CARBURETTED  HYDROGEN  GASES.  399 

REMARK. — Frequently  the  oxide  of  carbon  is  produced  at  the 
same  time  with  carbonic  acid.  The  pale  blue  flame  which  arises 
from  burning  charcoal,  especially  when  the  fire  is  nearly  burnt  out,  ap- 
pears to  be  produced  from  the  ignition  of  the  nascent  oxide  of  car- 
bon. As  fast  as  this  gas  is  formed,  it  takes  fire  and  burns  away, 
being  converted  into  carbonic  acid  gas.  Oxide  of  carbon  appears 
to  be  formed  in  those  combustions  of  carbon,  where  the  oxygen 
is  supplied  slowly  and  with  difficulty ;  carbonic  acid  gas,  where  it  is 
supplied  rapidly  and  in  large  quantities.  Hence,  when  we  heat  the 
oxides  of  mercury  with  charcoal,  we  obtain  carbonic  acid  ;  when  the 
oxides  of  iron,  we  evolve  oxide  of  carbon. 

We  have  every  reason  to  believe  that  oxide  of  carbon  is  one  of  the 
gases  produced  during  animal  and  vegetable  decomposition,  and  as  it 
is  highly  noxious,  it  may  contribute  to  their  injurious  effects. 

It  is  observed,  that  as  oxygen}  by  combining  with  carbon  to  form 
carbonic  acid,  becomes  heavier,  we  might  naturally  expect  that  car- 
bonic oxide,  containing  twice  as  much  carbon,  should  be  heavier 
still ;  but  this  does  not  follow.  Carbonic  acid  is  heavier  than  oxy- 
gen, by  precisely  the  additional  weight  of  the  carbon,  because  this 
last  has  assumed  the  aeriform  condition,  within  the  same  volume  as 
the  oxygen.  The  sp.  gr.  of  carbonic  acid  being  1.527,  if  we  deduct 
that  of  the  oxygen,  1.111,  we  have  .416  for  the  sp.  gr.  of  aeriform 
carbon  in  the  gas,  and  as  this  is  combined  with  only  half  a  volume  of 
oxygen,  which  is  expressed  by  .555 — this  added  to  the  weight  of 
the  carbon  =.97  If  for  the  gravity  of  the  carbonic  oxide,  which  is  to  be 
regarded,  therefore,  not  as  a  mere  solution  of  carbon  in  oxygen,  but 
as  a  combination  of  fieriform  carbon  with  oxygen  gas. 

CARBURETTED    HYDROGEN  GASES. 

1.  HISTORY. — Some  of  these  gases  must  have  been  for  a  long 
time,  more  or  less  known  to  mankind;  as  their  occurrence  is  fre- 
quent in  the  mud  of  marshes,  in  coal  mines,  in  the  matter  emitted 
from  burning  combustibles,  and  from  the  ultimate  results  of  animal 
digestion,  &ic. 

But  we  owe  the  accurate  knowledge  of  them  to  a  few  modern 
philosophers,  among  whom  Mr.  Dalton,  Dr.  Henry,  and  Dr.  Thom- 
son, are  conspicuous.* 

2.  GENERAL  VIEW. — It  seems,  at  first,  as  if  there  must  an  immense 
number  of  carburetted  hydrogen  gases  ;  since  we  can  scarcely  ope- 
rate by  destructive  processes,  upon  any  animal  or  vegetable  matter 


*  The  following  statements  of  facts  are  drawn  principally  from  the  writings  of 
Dr.  Henry  and  Dr.  Thomson. 

I  .972  is  the  number  we  have  hefore  stated. 


400  CARBURETTED  HYDROGEN. 

without  obtaining  inflammable  gases,  that  differ  in  sp.  gr. ;  in  combus- 
tibility ;  in  the  quantity  of  oxygen  required  to  saturate  them  ;  in  the  in- 
tenseness  of  light  emitted  while  they  are  burning,  and  in  many  other 
particulars.  The  ablest  analysts,  however,  among  whom  none  stand 
higher  than  the  gentlemen  already  named,  are  of  the  opinion  that  only 
a  few  species  have  been  distinctly  established,  and  that  the  apparent 
diversity  arises  from  innumerable  mixtures  of  these  with  each  other, 
with  other  gases,  and  with  various  vapors  derived  from  the  substances 
employed.  According  to  this  opinion,  which  is  probably  correct, 
the  compounds  of  carbon  and  hydrogen  exist  in  definite  proportions 
only,  "  with  this  peculiarity,  that  they  differ  from  each  other,  not  so 
much  in  the  relative  proportions  of  their  elements,  as  in  the  number 
of  volumes  or  atoms,  condensed  into  a  given  volume."* 

3.  CONSTITUTION  OF  THE  THREE  VARIETIES  THAT  ARE  BEST 
KNOWN. — Dr.  Henry. 

Prop,  by        Prop,  in 
weight,        vol.  carb. 
Sp.  gr.         carb.  hyd.         hydro. 

1.  Carburetted  hydrogen,  0.555,         6:2         1:2    }  condensed 

2.  Olefiant,  0.972,       12:2        2  : 2    >  into     one 

3.  Super-olefiant,  1.458?      18:3        3:3    )  volume. 
In  the  olefiant  and  the  super-olefiant — the  carbon  and  hydrogen  of 

each  gas  hear  the  same  relation  to  each  other,  and  the  gases  differ 
only  in  the  condensation  of  their  elements. — In  the  olefiant  gas,  one 
volume  contains  two  of  each  of  the  elements ;  in  the  super-olefiant 
three. 

The  gases  that  are  best  known,  are  divided  conveniently  into  light 
and  heavy  carburetted  hydrogen  gases  ;  of  the  former,  there  is  one 
variety  ;  of  the  latter,  there  are  two  or  more. 

LIGHT  CARBURETTED  HYDROGEN.f 

1.  PREPARATION. 

(a.)  By  stirring  with  a  stick,  the  mud  at  the  bottom  of  any  stag- 
nant water ;  bubbles  of  gas  will  rise,  which  may  be  inflamed  by  a 
lighted  taper  at  the  surface,  or  they  'may  be  collected  by  an  inverted 
pitcher,  filled  with  water,  or  by  a  bottle  filled  in  the  same  manner, 
and  having  a  funnel  in  its  mouth. 

This  gas  contains  in  mixture,  about  ¥V  °f  carbonic  acid,  which 
may  be  removed,  by  washing  with  lime  water,  or  with  solution  of 
caustic  potash  ;  there  is  also  present  from  yV  to  ^0-  of  nitrogen  gas. 


*  Dr.  Henry. 

t  Formerly  called  hydro-carburet  and  carbonated  hydrogen.  It  is  also  called 
proto-carburet  of  hydrogen,  heavy  inflammable  air  of  marshes,  &c.  but  the  name  in 
the  text  is  generally  used. 


CARBURETTED  HYDROGEN.  401 

b.  The  gas  distilled  from  mineral  coal — after  purification  with  li- 
quid potash  to  remove  the  carbonic  acid,  and  with  chlorine*  to  re- 
move the  olefiant  gas,  is  also  sufficiently  pure,  and  probably  the  same 
would  hold  nearly  true  of  the  gases  obtained  by  heating  the  follow- 
ing substances. 

(c.)  Anthracite  of  Pennsylvania  and  of  Rhode  Island,  the  latter 
moist  ;f  kernels  of  the  hickory  nut,  and  of  other  oleaginous  nuts  and 
seeds  ;  common  woods,  as  oak,  and  maple,  pine  and  pine  knots  ;  tar^ 
tar ;  recent  bone  ;  moist  charcoal ;  acetate  of  lead,  and  acetate  of 
copper  ;  spermaceti ;  tallow,  wax,  &c. 

(c?.)  In  these  mixed  gases,  there  are  variable  proportions  of  car- 
bonic acid — of  olefiant,  and  perhaps  sometimes  of  super-olefiant  gas, 
and  various  vapors. 

2.  PROPERTIES  OF  LIGHT  CARBURETTED  HYDROGEN  GAS.J 

(a.)  Colorless  and  tasteless,  not  absorbable  by  water,  which,  how- 
ever, after  having  been  previously  boiled,  takes  up  about  ¥V  °f  ^ 
volume. 

(b.)  Odor  slight — when  it  is  otherwise,  it  is  derived  from  mixture 
with  other  gases  and  vapors,  especially  when  the  gas  is  distilled  from 
bituminous  coal. 

(c.)  Sp.  gr.  .555,  air  being  1  ;  consequently,  100  cubic  inches 
weigh,  at  mean  temperature  and  pressure,  16.944  grains,  just  half 
as  much  as  oxygen  gas.  Its  sp.  gr.  is  thus  obtained  by  calcula- 
tion; it  consists  of  1  vol.  vapor  of  carbon,  which  weighs  .4166§-f  2 
vol.  of  hydrogen,  .0694x2  =  . 1388  =  . 555,  which  is  exactly  the 
weight  of  carburetted  hydrogen  obtained  by  experiment. 

(d.)  Extinguishes  burning  bodies,  but  is  itself  inflammable  ;  burns 
from  a  jet,  with  a  flame,  which  is  yellow  or  variously  tinged;  its 
power  of  illuminating  is  much  greater  than  that  of  hydrogen  gas. 

(e.)  Mixed  with  from  6  to  12  volumes  of  atmospherical  air,  it  ex- 
plodes with  violence  by  contact  of  a  lighted  taper. 

(f.)  More  violently  with  oxygen  gas — the  latter  must  exceed  the 
inflammable  gas  in  volume,  but  must  not  be  over  two  and  one  fourth 
times  its  bulk.  » 

(g.)  Loses  its  combustibility,  if  rarefied,  so  that  the  pressure  is  less 
than  one  fourth  part  that  of  the  atmosphere. 


*  Chlorine  has  the  property  of  removing  the  heavy  species  of  carburetted  hydro- 
gen, to  form  with  it  a  peculiar  compound,  the  chloric  ether,  which  has  been  regard- 
ed, but  erroneously,  as  an  oil.  This  property  of  chlorine  must  be  repeatedly  men- 
tioned in  giving  the  account  of  the  carburetted  hydrogen  gases,  and  will  be  again 
illustrated  In  its  proper  place.  t  See  Am.  Jour.  Vol.  X,  p.  331. 

t  That  obtained  from  the  marshes  is  the  purest  variety. 

§  For  carbonic  acid  has  the  sp.  gr.  1.527,  from  which  deduct  that  of  the  1  vol.  of 
oxygen  which  it  contains,  1.111,  which  leaves  .416  for  the  weight  of  the  carbon  in 
vapor. 

51 


402  OLEFIANT  GAS. 

(h.)  Carbonic  acid  and  other  gases,  also  diminish  its  inflamma- 
bility. 

(i.)  Its  complete  combustion  requires  more  than  two  volumes  of  ox- 
ygen— two  are  consumed,  and  carbonic  acid,  equal  in  volume,  to  the 
inflammable  gas,  is  produced  and  water  is  formed. 

(/.)  There  being  in  carbonic  acid  exactly  its  volume  of  oxygen, 
it  follows  that  half  the  gas  used  went  to  form  water  along  with  the  hy- 
drogen, of  which  there  were  therefore  2  volumes,  and  this,  along  with 
1  of  gaseous  carbon,  existed  in  the  compass  of  1  volume. 

(k.)  It  hence*  results  that  the  light  carburetted  hydrogen  gas  is 
composed  for  100  cub.  inches,  at  med.  temp,  and  pressure,  of 
charcoal,    12.69  grains,  74.87  grains, 
hydrogen,    4.26      "       25.13     " 


16.95f          100.00 

(/.)  On  respiration  and  animal  life,  its  effects  are  eminently  noxious, 
and  speedily  fatal. 

(m.)  Not  decomposed  by  electricity,  nor  by  heat  in  ignited  tubes, 
unless  very  intense,  as  stated  above. 

4.  CONSTITUTION. — Two  volumes  of  hydrogen  and  one  volume 
of  gaseous  carbon,  condensed  into  one  volume  ;  1  equivalent  of  char- 
coal, =  6-}-2  of  hydrogen,  =8  for  the  equivalent  of  the  compound. 

OLEFIANT    GAS.J 

1.  HISTORY. — Discovered  at  Haarlem,  in  Holland,  in  1796,  by 
the  associated  Dutch  chemists  ;  but  Mr.  Dalton,  of  Manchester, 
gave  the  first  accurate  account  of  its  composition. 

2.  NAME. —  With  chlorine,  in  equal  volumes,  it  is  condensed  into 
a  substance  resembling  an  oil  ;  hence  the  name,  from  oleum  Jio  ;  the 
compound  substance  produced,  being  however,  not  an  oil,  the  name 
was  unappropriate,  but  it  is  still  generally  retained. 

3.  PREPARATION.^ 

(a.)  Alcohol  1  measure,  sulphuric  acid  2  or  3  ;  mix  them  cau- 
tiously, in  a  retort,  of  which  they  must  not  occupy  more  than  J  of 
the  body.  Gentle  heat  is  gradually  applied — the  mixture  soon  be- 

*  16.93. — Dr.  Turner.     16.94,  on  p.  401,  (e.)  of  this  work. 

t  For  carbonic  acid,  with  1  vol.  carbon  and  1  of  oxygen,  weighs  46.597  grains  for 
the  100  cub  inches,  deduct  the  weight  of  the  oxygen,  33.888,  leaves  12.70  nearly, 
for  the  weight  of  the  carbon  in  vapor,  and  the  weight  of  hydrogen  being,  for  100  cu- 
bic inches,  2.118  ;  twice  that  sum  is  4.236,  and  this*+12. 70  =16.936.  These  numbers 
are  taken  from  Brande's  Tables,  and  vary  slightly  from  those  quoted  elsewhere  in 
the  pages  of  this  work. 

I  Or  heavy  carburetted  hydrogen  gas,  bi-carburetted,  and  per-carburetted  hydro- 
gen, and  hydroguret  of  carbon.  The  first  name,  that  of  olefiant  gas,  is  generally 
employed. 

§  By  passing  the  vapor  of  alcohol  over  ignited  siliceous,  or  argillaceous  earth, 
nearly  pure  olefiant  gas  is  obtained. 


OLEFIANT  GAS.  403 

comes  black,  froths,  and  emits  gas,  which,  when  it  burns  quietly 
with  a  bright  flame,  may  be  saved  ;  it  is  received  over  water. 

(6.)  As  the  mixture  puffs  up  very  much,  especially  towards  the 
end  of  the  process,  the  heat  must  be  very  carefully  managed,  and 
should  never  exceed  that  of  a  chafing  dish. 

(c.)  Sulphurous  acid  comes  over,  which  the  water  will  absorb,  and 
carbonic  acid  is  formed,  but  this,  as  well  as  the  other  gas,  is  remov- 
ed by  solution  of  caustic  alkali. 

(d.)  The  olefiant  gas  is  derived  from  the  alcohol,  whose  consti- 
tution is  altered  by  the  sulphuric  acid,  principally,  as  is  imagined,  by 
its  uniting  with  the  water.* 

4.  PROPERTIES. 

(a.)  Invisible — little  odor,  except  from  sulphuric  ether,  which  is 
formed  in  the  process  ;  I  have  always  observed  however,  that  it  re- 
tains the  ethereal  smell  for  a  long  time.  Water  8  vols.  absorbs  1  of 
this  gas. 

(6.)  Sp.  gr.  972, f  air  being  1.  It  is  remarked  that  nitrogen  gas, 
carbonic  oxide,  and  olefiant  gas  have  the  same  gravity ; {  and  that 
100  cubic  inches,  at  the  medium  temperature  and  pressure  therefore 
weigh  29.64  grains.  As  it  consists  of  2  vols.  of  vapor  of  carbon, 
and  2  vols.  of  hydrogen,  its  sp.  gr.  is  easily  obtained  by  calcula- 
tion, thus.  Twice  the  sp.  gr.  of  hydrogen  gas,  0694  x2  =  1388-{- 
twice  the  sp.  gr.  of  the  vapor  of  carbon,  4166x2=8333,  and  this 
number  4-1388  =  .972. 

(c.)  Extinguishes  burning  bodies,  but  issuing  from  a  jet,  and 
kindled  by  a  candle,  this  gas  burns  with  extreme  brilliancy,  the  flame 
resembling  that  of  the  brightest  lamp  ;  it  far  surpasses  simple  carbu- 
retted  hydrogen. 

(d.)  Mixed,  1  vol.  with  3  vols.  of  oxygen  gas,  and  inflamed,  it  de- 
tonates with  great  violence,  and  much  care  is  requisite  to  avoid  ac- 
cidents. If  done  in  glass  vessels,  they  should  be  small  and  strong, 
but  it  is  better  to  use  plate  tin,  or  copper  tubes. 

(e.)  The  explosion  may  be  made  in  a  detonating  eudiometer  tube, 
by  electricity,  but  only  a  cubic  inch  of  the  mixed  gases  should  be 
employed. 

(f.)  One  volume  of  this  inflammable  gas,  requires  3  of  oxygen  for 
saturation,  and  gives  two  volumes  of  carbonic  acid  gas. 

(g.)  Dr.  Henry  remarks,  that  in  order  to  insure  the  perfect  com- 
bustion of  the  gas,  it  should  be  mixed  with  5  volumes  of  oxygen  gas, 
of  at  least  90  per  cent,  purity. 


*  For  a  more  particular  view  of  the  theory,  see  alcohol. 
t  Thomson's  First  Principle,  Vol.  I,  p.  149. 

t  The  Dutch  chemists  made  that  of  olefiant  gas,  .909 — Dr.  Henry,  some  years 
ago,  .967— Saussure  Jr.  .9852. 


404  OLEFIANT  GAS. 

5.  MODE  OF  ESTIMATING  ITS  COMPOSITION. 
(a.)  If  too  little  oxygen  be  used,  charcoal  precipitates  unburnt, 
and  the  volume  of  the  residue  is  greater  than  that  of  the  original 
gases. 

(b.)  Upon  the  same  principles  of  calculation  as  those  upon  which 
the  composition  of  the  light  carburetted  hydrogen  gas  was  determin- 
ed, it  follows  that  in  100  cubic  inches  there  are — 

Charcoal,         25.38         85.63  grains,         100. 
Hydrogen,         4.26         14.37     "  16.71 


29.64*     100.00  116.71f 

(c.)  Olefiant  gas  has  therefore  100  grains  of  charcoal  united  to 
16.71  of  hydrogen,  while  the  light  carburetted  hydrogen  has  the 
same  weight  of  carbon,  with  33.41  of  hydrogen,  just  double  ;  in 
other  words,  the  carbon  being  given,  it  has  half  the  hydrogen,  and 
the  hydrogen  being  given,  it  has  double  the  carbon. 

6.  CONSTITUTION. 

As,  in  the  combustion  of  olefiant  gas,  3  vols.  of  oxygen  disappear, 
water  is  formed,  and  2  vols.  of  carbonic  acid  are  produced,  it  is  evi- 
dent that  as  oxygen  does  not  change  its  volume  by  combining  with 
carbon,  to  form  carbonic  acid,  2  volumes  of  the  oxygen  have  gone 
into  the  carbonic  acid  with  2  volumes  of  carbon ;  the  other  volume 
of  oxygen  has  formed  water,  and  as  two  volumes  of  hydrogen  are 
demanded  for  this  purpose,  it  follows  that  each  volume  of  olefiant 
gas  contains  2  volumes  of  carbon,  -f-2  volumes  of  hydrogen,  =2 
equivalents  of  each.  The  compound  will  therefore  weigh  12 -f  2  = 
14,  its  equivalent.J 

If  2  grains  of  sulphur  be  heated  over  mercury,  with  1  cubic  inch 
of  olefiant  gas,  2  cubic  inches  of  light  carburetted  hydrogen  will  be 
obtained,  and  charcoal  precipitated. — Ure. 

7.  MISCELLANEOUS.^ 

(«.)  In  olefiant  gas  there  is  so  large  a  proportion  of  carbon,  that 
when  a  jet  of  the  flame  is  permitted  to  play  against  a  white  earthen 
plate,  it  covers  it  with  charcoal,  and  the  jet  burning  freely  in  the  air, 
emits  a  column  of  lamp  black. 

(b.)  Olefiant  gas  is  decomposed  by  electricity ;  and  by  ignition  in 
porcelain  tubes ;  products,  charcoal  and  hydrogen,  the  latter  in  a 
volume  double  -to  that  of  the  gas  decomposed. 

In  the  experiment  with  the  tube,  by  varying  the  heat,  we  can 
cause  it  to  deposit  more  or  less  charcoal. 


*  Dr.  Turner  states  this  number  at  29.65,  and  that  for  two  volumes  of  hydrogen 
at  4.23.  t  See  p.  403,  (4.  &.)  JHenry,  Vol.  I,  p.  425,  10th  Ed. 

§  The  action  of  chlorine  and  iodine  upon  the  carburetted  hydrogen  gases,  will  be 
considered  under  those  heads. 


CARBON  AND  HYDROGEN.  405 

SUPER-OLEFIANT    GAS. 

1.  REMARK. — We  mention  this  gas,  (whose  distinct  existence  is 
highly  probable,  but  not  perhaps  fully  proved,)  out  of  respect  to  Mr. 
Dalton,  and  Dr.  Henry,  to  whom  science  is  so  much  indebted,  es- 
pecially in  relation  to  the  inflammable  gases. 

2.  HISTORY. — Dr.   Henry,  in  the  Phil.   Trans,   for   1821,  has 
given  an  account  of  the  discovery  of  this  gas  by  Mr.  Dalton,  which 
has  not  been  obtained  in  a  separate  form,  but  mingled  with  other 
varieties,  in  the  gases  obtained  from  oil,  coal,  &c. 

3.  PROPERTIES. 

(a.)  For  complete  combustion,  1  volume  requires  4j  of  oxygen, 
and  produces  3  of  carbonic  acid. 

(b.)  Sp.  gr.  estimated  at  1.4,  but  Dr.  Henry  thinks  that  if  con- 
stituted as  he  supposes,  of  3  volumes  of  gaseous  carbon,  and  3  vol- 
umes of  hydrogen,  condensed  into  1  volume,  its  specific  gravity  must 
be  1.458,  derived  from  multiplying  the  sp.  gr.  of  hydrogen,  .0694, 
and  that  of  gaseous  carbon,  .4166,  each  by  3,  and  adding  the  pro- 
ducts together. 

(c.)  A  portion  of  a  gas  which  contained  more  than  40  per  cent, 
of  the  super-olefiant,  was  cooled  by  muriate  of  lime  and  snow,  but 
no  liquid  was  deposited  from  it ;  it  was  condensible  by  chlorine,  but 
the  product  has  a  peculiar  odor,  unlike  that  of  chloric  ether. 

OTHER    COMPOUNDS    OF    CARBON    AND    HYDROGEN. 

It  is  believed  that  there  are  four  or  five  more  of  these  compounds, 
in  which  the  constituent  principles  bear  the  same  proportion  to  each 
other,  but  differing  in  the  degree  of  condensation. 

1 .  It  is  supposed  that  a  compound  may  exist  of  1  volume  of  car- 
bon, and  of  1  of  hydrogen,  condensed  into  1  :  the  sp.   gr.   of  this 
would  be,  for  the  carbon  vapor,  .4166,  and  for  the  hydrogen,  .0694, 
the  sum  of  which  would  be,  .4860 ;  but  this  has  not  yet  been  dis- 
covered, although  Dr.  Thomson  and  Dr.  Henry,  concur  in  suggest- 
ing that  it  may  yet  be  found.* 

2.  Dr.  Thomson  inferred  that  another  compound  might  exist  in 
the  vapor  of  ether,  in  union  with    1   volume  of  aqueous  vapor.     He 
supposed  that  it  might  consist  of  4  volumes  of  vapor  of  carbon,  and 
4  volumes  of  hydrogen,  condensed  into  1  volume  ;  it  would  of  course 
have  twice  the  sp.  gr.  of  olefiant  gas,  that  of  1.9444  :  it  would  require 
6  vols.  of  oxygen,  for  its  entire  combustion,  and  would  produce  4  vols. 
of  carbonic  acid.f     Its  equivalent  would  of  course  be  28,  composed 
of  4  X  6  for  the  carbon,  and  4X1  for  the  hydrogen. 

Dr.  Thomson  gave  it  the  provisional  name  of  quadro-carburet. 
This  compound  has  since  been  discovered  by  Mr.  Faraday.  In  Mr. 

*  Perhaps  as  a  constituent  of  coal  gas. 

t  Hence,  adding  the  number  representing  the  sp.  gr.  of  aqueous  vapor,  Dr.  Thom- 
son inferred  that  the  sp.  gr.  of  the  vapor  of  ether  must  be  1.9444+06250=2.5694. 


406  CARBON  AND  HYDROGEN. 

Gordon's  patent  oil  gas  lamp,  the  gas  is  compressed  by  a  force  of  30 
atmospheres,  and  a  limpid  fluid*  is  obtained,  which  appears  to  contain 
several  compounds  of  carbon  and  hydrogen.  If  this  fluid  be  heated 
by  the  hand,  and  the  vapor  condensed  into  a  tube,  cooled  to  0,  it 
becomes  a  fluid,  which  remains  such  only  below  32°  Fahr.  and 
even  before  that  temperature  is  attained,  it  is  reconverted  into  vapor, 
which  burns  with  a  brilliant  flame.  Its  sp.  gr.  is  1.9065,  very  near 
that  calculated  for  it  by  Dr.  Thomson,  before  its  discovery.  It  is 
slightly  absorbed  by  water  ;  more  by  alcohol,  but  is  evolved  from  the 
latter,  with  effervescence,  by  water.  At  0  it  is  again  condensed, 
and  the  fluid  having  the  sp.  gr.  of  0.627,  is  the  lightest  known. 
Sulphuric  acid  absorbs  100  times  its  volume,  and  its  color  is  dark- 
ened, but  no  sulphuric  acid  is  disengaged. 

Its  analysis  by  oxygen  is  exactly  what  was  predicted  by  Dr. 
Thomson  ;  as  to  the  quantity  of  gas  required,  the  carbonic  acid  pro- 
duced, the  proportions  of  its  constituents,  and  the  equivalent  num- 
ber, as  already  stated. 

3.  Dr.  Thomson  supposes  that  the  vapor  of  the  fluid  distilled  from 
coal  tar,  and  which  is,  from  its  similarity  to  mineral  naptha,  called  by 
the  same  names,  consists  t)f  6  equivalents  of  vapor  of  carbon  +6  of 
hydrogen,  condensed  into  1.     Its  equivalent  number  is  of  course 
42 ;  it  requires  6  vols.  of  oxygen  for  its  complete  combustion,  and 
there  are  produced  6  of  carbonic  acid.     This  'compound  is  supposed 
to  exist  in  the  coal  gases,  and  as  their  light  is  in  direct  proportion  to 
the  quantity  of  carbon  which  they  contain,  it  is  obvious  that  upon  this 
view,  the  vapor  of  naptha  will  give  three  times  as  much  light  as  defi- 
ant gas.     Its  sp.  gr.  must,  of  course  be  2.9166.     In  pure  naptha, 
potassium  remains  unoxidized,. which  proves  the  absence  of  oxygen. 

4.  In  the  liquid  obtained  by  the  condensation  of  coal  gas,  Mr.  Fa- 
raday discovered  another  compound  of  carbon  and  hydrogen.     This 
fluid,  when  recent,  boils  at  60°  Fahr. ;  one  tenth  being  exhaled,  the 
boiling  point  rises  to  100°,  and  the  whole  is  not  evaporated  till  it  rises 
to  250°.     It  thus  appeared  probable  that  there  were  different  com- 
pounds, differing  in  volatility,  and  by  condensing  the  vapor  at  differ- 
ent temperatures,  he  attempted  to  obtain  them  separate.     The  boil- 
ing point  appearing  more  constant  between   176°,  and  195°,  than 
any  where  else,  he  carried  on  the  distillation  within  those  limits,  and 
by  repeating  it,  and  condensing  the  vapor  at  0,  he  obtained  a  fluid 
which  he  called  bi-carburet  of  hydrogen. 

Its  properties  are  as  follows ;  it  is  a  transparent  colorless  fluid, 
smells  like  oil  gas,  or  almonds;  at  60°,  sp.  gr.  .850,  and  that  of  its 
vapor  2.776.  At  32°,  it  becomes  solid  and  crystalline ;  at  0  trans- 
parent and  crumbles  into  grains,  having  nearly  the  hardness  of  loaf 

*  About  1  gallon  for  1000  cubic  feet  of  good  gas.— Phil.  Trans.  1825,  p.  441. 


NAPTH  ALINE:  407 

sugar.  Boiling  point,  186°,  evaporates  spontaneously ;  soluble,  in 
fixed  and  volatile  oils,  and  in  ether  and  alcohol,  from  which  it  is 
thrown  down  by  water. 

It  burns  readily  and  brilliantly,  and  with  much  smoke ;  in  oxygen 
gas  its  vapor  rises  and  forms  a  detonating  mixture.  Potassium  re- 
tains its  lustre  in  it,  even  when  heated.  By  passing  it  in  vapor 
through  an  ignited  tube,  charcoal  is  deposited,  and  carburetted  hy- 
drogen obtained.  Its  analysis  was  performed  by  detonation  with 
oxygen  ;  and  by  passing  it  over  ignited  oxide  of  copper ;  carbonic  acid 
and  water  were  the  only  products,  and  as  there  is  no  oxygen  in  it,  it 
follows  that  it  is  composed  of  carbon  and  hydrogen  only.  It  requires 
750  measures  of  oxygen  to  burn  100  of  its  vapor;  600  unite  with 
600  of  carbon  vapor,  and  150  with  300  of  hydrogen,  and  therefore 
its  constitution  is  6  equivalents  of  carbon,  and  3  of  hydrogen,  and  of 
course  the  equivalent  of  the  compound  is  6x6—36  +  1x3=39. 
The  sp.  gr.  of  its  vapor  is  easily  inferred ;  for  the  weight  of  the  va- 
por of  carbon  -4166  X  6=2.4996,  and  that  of  hydrogen  .0694  X  3  = 
0.2082=2.7078,  and  this  is  very  near  to  the  number  obtained  by 
Mr.  Faraday. 

NAPHTHALINE. 

A  substance  to  which  this  name  has  been  applied,  was  first  ob- 
served by  Mr.  Garden  and  afterwards  examined  by  Dr.  Kidd  of  Ox- 
ford Univ.  * 

It  is  obtained  from  coal  tar ;  the  naptha  passes  first  by  a  very  gen- 
tle distillation,  and  afterwards  the  naphthaline  in  vapor,  which  con- 
denses in  the  neck  of  the  retort,  in  the  form  of  a  white  crystalline 
solid. 

Properties. — Sp.  gr.  1 .048  ;  taste  pungent  and  aromatic  ;  odor 
peculiar,  and  said  to  resemble  that  of  narcissus;  to  the  touch  smooth 
and  unctuous;  color  white;  lustre  silvery;  soluble  in  alcohol  and 
ether,  in  olive  oil,  in  oil  of  turpentine,  and  in  naptha ;  not  very  in- 
flammable, but,  when  kindled,  burns  rapidly,  with  much  smoke ; 
fusible  at  180°;  evaporates  at  the  common  temperature  and  boils 
at  410°;  its  condensed  vapor  readily  crystallizes  in  thin  trans- 
parent laminae.  By  Dr.  Thomson's  analysis,  naphthaline  consists  of 
one  equivalent  and  a  half  of  carbon  9,  and  of  1  of  hydrogen,  and  its 
own  equivalent  is  therefore  10.  According  to  Dr.  Thomson's  views 
it  is,  therefore,  a  scsqui-carburet.  It  appears  to  form,  with  sulphuric 
acid,  another  peculiar  acid,  to  which  the  name  of  sulpho-naphthalic 
has  been  given,  and  its  compounds  have  been  called  sulpho-naph- 
thalates.  There  is  also  an  acid,  apparently  formed  by  the  action  of 
nitric  acid.  It  is  scarcely  necessary  to  detail  the  particulars  of  these 
unimportant  compounds.* 

*  Phil.  Trans.  1825,  Part  II,  and  Ann.  of  Philos.  XXVII,  44,  and  New  Series, 
VI,  136.  Eng.  Quar.  Jour.  VIII,  289.  Murray.  Turner. 


408  MIXED  GASES. 

MIXED  GASES  ;  obtained  by  heating  various  combustible  bodies, 
as  tallow,  alcohol,  ether,  bituminous  coal,  &ic. 

Remark. — Although,  as  has  been  already  observed,  these  gases 
are,  in  all  probability,  mixtures  of  the  varieties  that  have  been  de- 
scribed, they  do,  in  practice,  present  some  peculiarities  worthy  of  be- 
ing noted. 

I.  COAL  GAS. 

(a.)  There  is  so  much  variety  in  the  properties  of  the  gases  ob- 
tained by  heating  mineral  coal,  that  they  are  hardly  worthy  of  being 
grouped  together,  except  on  the  ground  that  they  are  obtained  from 
a  common  material. 

•    (6.)  Bituminous  coal,  distilled  in  an  iron  retort,  affords,  besides  the 
permanent  gases,  tar  and  solution  of  carbonate  of  ammonia. 

(c.)  The  gas  varies  in  quality,  even  from  the  same  coal,  at  dif- 
ferent stages  of  the  process,  according  to  the  degree  of  heat  and  the 
manner  of  applying  it ;  of  course,  it  varies  with  different  specimens 
of  coal. 

(d.)  Dr.  Henry  remarks,  "within  certain  limits,  the  more  quickly 
the  heat  is  applied,  the  greater  is  the  quantity  and  the  better  the  qual- 
ity, of  the  gas  obtained  from  coal ;  for,  too  slow  a  heat  expels  the 
inflammable  matter  in  the  form  of  tar."* 

(e.)  The  gas  declines  much  in  quality  towards  the  end  of  the  oper- 
ation, although  we  still  continue  to  obtain  large  quantities. 

K)  The  useful  part  of  the  gas  is  composed  of  mixtures  of  light 
leavy  carburetted  hydrogen,  in  endlessly  varied  proportions. 

(g.)  The  useless  gases  are  carbonic  acid,  oxide  of  carbon,  nitro- 
gen and  sulphuretted  hydrogen,f  and  sometimes  ammonia,  (and  sul- 
phurous acid  gas?) 

(h.)  The  disagreeable  smell  arising  from  sulphuretted  hydrogen, 
and  probably  a  little  sulphuret  of  carbon,  may  be  washed  out  by  cream 
of  lime,  without  injuring  the  combustibility  of  the  gas. 

(i.)  The  best  gas  has  the  sp.  gr.  of  at  least  650,  air  being  1,  "  and 
each  volume  consumes  about  2J  volumes  of  oxygen  and  gives  1 J  vol- 
ume of  carbonic  acid." 

(/.)  "  The  last  portions  have  a  sp.  gr.  as  low  as  .340,  and  each 
volume  consumes  about  .8  of  a  volume  of  oxygen  gas  and  gives  about 
.3  of  a  volume  of  carbonic  acid." 

(k.)  Chlorine,  applied  in  a  manner  hereafter  to  be  pointed  out, 
detects  from  13  to  20  per  cent  of  olefiant  gas;  the  rest  is  chiefly  light 
carburetted  hydrogen. 


*  Phil.  Trans.  1808,  1820,  1824. 

t  Dr.  Henry  refers  us,  for  the  method  of  separating  them,  to  his  memoirs  above 
quoted,  to  Manchester  Memoirs,  and  Annals  of  Philosophy,  XV. 


MIXED  GASES.  409 

(/.)  The  last  portions  contain  hardly  any  olefiant  gas;  they  con- 
sist of  light  carburetted  hydrogen,  and  much  hydrogen  and  carbonic 
oxide,  which  is  the  reason  that  they  afford  so  little  light  during  their 
combustion. 

(m.)  There  is  great  uncertainty  and  variety  in  the  quantity  and 
quality  of  gas  obtained  from  coal. — Dr.  Henry  considers  it  as  an  ap- 

Eroximation  to  truth,  to  suppose,  that  112  Ibs.  of  good  coal  may  af- 
>rd  from  450  to  500  cubic  feet  of  gas,  "of  such  quality,  that  half  a 
cubic  foot  per  hour  is  equivalent  to  a  mould  candle  of  six  to  the  pound, 
burning  during  the  same  space  of  time." 

(n.)  I  have  often  obtained  a  very  bright  burning  gas  from  Rich- 
mond (Va.)  coal ;  at  other  times  a  gas  producing  a  very  pale  flame. 
*  (o.)  Anthracite  of  Pennsylvania  and  of  Rhode  Island,*  afford 
much  gas,f  chiefly  light  carburetted  hydrogen,  but  it  is  unfit  for  illu- 
mination; most  authors  state  that  the  anthracties  afford  little  or  no 
gas.  That  of  Wilkesbarre  gave,  in  my  trials,  40  wine  pints  from 
886  grains  of  the  coal,  while  the  specific  gravity  of  the  coal  was  in- 
creased from  1.65  to  1.77,J  and  several  other  varieties  of  American 
anthracite  yielded  large  quantities  of  inflammable  gas. 
II.  OIL  GAS. 

1.  HISTORY. 

(a.)  The  familiar  use  made  of  animal  oils,  to  afford  by  their 
combustion,  artificial  light,  naturally  suggested  the  project  of  decom- 
posing them  to  obtain  gas. 

(6.)  Dr.  Henry,  in  a  memoir  in  Nicholson's  Journal  for  1805,  ap- 
pears to  have  first  brought  this  subject  into  notice,  and  to  have  proved 
that  next  to  the  pure  olefiant,  the  gas  from  oil  is  the  best  adapted  for 
artificial  illumination. 

2.  PREPARATION  AND  PROPERTIES. 

(a.)  By  allowing  spermaceti  oil,  or  even  refuse  whale  oil,  (as  the 
purity  of  the  oil  is  not  material,)  to  fall  drop  by  drop,  from  a  reser- 
voir furnished  with  a  stop  cock,  and  connected  by  a  tube  with  an 
iron  bottle  or  cylinder,  upon  fragments  of  bricks,  or,  as  practised  in 
New  York,  fragments  of  anthracite,  heated  to  a  cherry  red. 

(6.)  A  condensing  vessel  should  be  interposed  between  the  fur- 
nace and  the  gazorneter,  to  receive  the  undecomposed  oil. 

(c.)  A  wine  gallon  of  oil  affords  100  cubic  feet  of  gas,  whose 
specific  gravity  exceeds  .900 ;  more  than  .40  of  this  gas  is  condensi- 
ble  by  chlorine ;  100  volumes  require  200  of  oxygen  to  saturate  them 
and  produce  158  of  carbonic  acid. 


*  The  latter  must  be  moist. 

t  It  is  not  easy  to  say  how  much  of  this  gas  arises  from  water ;  the  increase  of  sp. 
gr.  in  consequence  of  ignition,  seems  however  to  imply  that  a  lighter  constituent  of 
the  mineral  has  been  expelled.  J  Am.  Jour.  Vol.  X,  p.  355,  and  Vol.  XI,  p.  78. 

52 


410  MIXED  GASES. 

(d.)  Wigan  coal  has  been  esteemed  the  hest  in  England ;  the  gas 
from  this  coal,  required,  on  an  average,  only  155  volumes  of  oxygen 
to  100  of  the  coal  gas,  and  gave  88  measures  of  carbonic  acid. 

(e.)  As  the  inflammable  gases  produce  light  just  in  proportion  to 
the  quantity  of  carbon  they  contain,  it  follows,  that  oil  gas  is  nearly 
or  quite  as  powerful  as  gas  from  Wigan  coal. 

3.  MISCELLANEOUS. 

(a.)  Mr.  Brande  estimates,  that  to  produce  a  quantity  of  light 
equal  to  that  of  ten  wax  candles,  burning  for  one  hour,  there  are  re- 
quired 2600  cubical  inches  of  olefiant  gas,  4875  of  oil  gas  and  13120 
of  coal  gas. 

(b.)  Dr.  Henry  suggests  that  this  estimate  is,  as  regards  coal  gas, 
rather  low,  and  is  disposed  to  consider  1  volume  of  oil  gas  as  equiva- 
lent to  2  or  2J  of  coal  gas. 

(c.)  The  late  Mr.  Creighton,  of  Glasgow,  considered  2  volumes 
good  coal  gas  as  equal,  in  affording  light,  to  only  one  of  oil  gas,  and 
valuing  the  quantity  of  light  given  by  one  pound  of  spermaceti  candles 
at  1  shilling,  he  estimated  the  cost  of  an  equal  effect  from  sperm  oil, 
burning  in  an  Argand's  lamp,  at  6 JJ.  that  from  whale  oil  at  4jc?.  and 
that  from  coal  gas  at  2jdf.  "  Twenty  cubic  feet  of  coal  gas,  or  ten 
of  oil  gas,  he  considers  as  equivalent  to  a  pound  of  tallow,  and  5000 
grains  of  spermaceti  oil  to  7000  of  tallow  or  1  Ib.  avoirdupois." 

(d.)  Dr.  Henry  sums  up  the  comparative  claims  of  oil  and  coal 
gas,  by  saying,  that  for  oil  gas,  vessels  and  tubes  of  half  the  size  are 
sufficient  ;*  no  washing  is  needed ;  there  is  no  residuum  ;  the  light  is 
brighter  and  the  heat  less ;  but  that  still,  in  large  establishments  and 
in  countries  where  coal  is  cheap,  the  latter  will  be  preferred  on  the 
score  of  economy. 

(e.)  The  best  criterion  of  the  illuminating  power  of  a  gas  is  the 
quantity  of  oxygen  required  for  its  perfect  combustion,!  and  the 
amount  of  carbonic  acid  produced ;  specific  gravity  is  deceptive,  for 
it  may  be  affected  by  foreign  gases,  for  instance,  by  carbonic  oxide 
or  by  carbonic  acid.  J 

(/.)  It  appears  that  a  very  valuable  illuminating  gas  is  obtained  by 
decomposing  cotton  seed  by  a  well  managed  heat.  Prof.  Olmsted 
lias  shewn  that  it  is  both  economical  and  effectual^ 

(g.)  Coal  gas  is  obtained  by  decomposing  coal  in  an  iron  retort ; 
the  tar  is  received  in  a  condensing  vessel,  and  more  continues  to  be 
deposited  by  the  passage  of  the  gas  through  vertical  tubes  kept  cold. 
The  gas,  under  strong  pressure,  is  passed  through  lime  diffused  in 


*  Oil  gas,  being;  free  from  sulphuretted  hydrogen,  needs  no  purification,  and  is 
therefore  peculiarly  fitted  for  dometic  use. 

t  It  is  suggested  that  condensation  by  chlorine  niay  be  a  test  equally  decisive.— 
Comm. 

I  Henry's  Chem.  Vol.  I,  p.  432,  10th  ed. 

§  Am,  Jour,  Vol.  XIII,  p.  194,  and  Vol.  X. 


MIXED  GASES,  411 

water,  or  through  successive  layers  of  hydrate  of  lime,  to  remove 
carbonic  acid,  sulphuretted  hydrogen,  &c. ;  it  is  finally  received  in  a 
gazometer,  (see  p.  214,)  thence  distributed  by  tubes,  and  burned  at 
proper  orifices  furnished  with  stop  cocks. 

(h.)  It  is  now  evident,  that  the  illuminating  power  of  gases  is  de- 
pendent not  only  upon  the  quantity  of  olefiant  gas  in  them  but  upon 
the  other  compounds  containing  still  more  carbon,  as  the  quadro- 
carburet,  the  vapor  of  naphtha,  &c. 

(*.)  Mr.  Daniel  employs  resin,*  dissolved  in  oil  of  turpentine ;  it 
falls,  drop  by  drop,  into  the  retort,  and  the  volatile  oil,  by  passing 
over  in  vapor,  is  recovered.  This  gas  is  employed  by  Mr.  Gordon 
in  his  portable  lamps,  and  is  said  to  be  equal  to  oil  gas. 

PORTABLE  GAS  LIGHT. 

"One  of  the  greatest  obstacles  to  the 
general  employment  of  gas  lights,  as  a  sub- 
stitute for  candles  and  lamps,  is  the  neces- 
sity of  pipes  leading  from  gazometers,  to 
all  situations  where  the  light  is  wanted.  The 
condensation  of  the  gas  in  strong  metallic 
receivers,  has  been  resorted  to  in  order  to 
obviate  this  difficulty.  This  process  may 
be  illustrated  by  means  of  the  apparatus 
described  for  the  impregnation  of  water 
with  carbonic  acid. 

"It  is  only  necessary  to  exchange  the 
communication  with  the  reservoir  of  car- 
bonic acid  gas,  for  a  similar  communication 
with  a  reservoir  of  olefiant  gas,  and  the  cop- 
per vessel  being  first  exhausted  of  air,  to 
condense  the  gas  into  it.  The  syphon  used 
to  draw  off  the  carbonated  water,  is  repla- 
ced by  a  tube  and  cock,  terminating  in  a 
capillary  perforation.  Through  this,  the 
gas  may  be  allowed  to  escape  in  a  proper 
quantity  to  produce  a  gas  light  when  inflamed." — Dr.  Hare. 

SAFETY  LAMP  OF  SIR  H.  DAVY. 

1.  REMARKS. 

(a.)  It  has  long  been  notorious  that  a  deadly  gas  infests  the  mines 
of  bituminous  coal,  called  by  the  miners,  the  fire  damp  or  wild  fire, 


*  Dr.  Hare,  several  years  ago,  employed  common  rosin,  in  New  York,  and  it  is 
now  used  there  to  afford  gas  light;  he.  obtained  also  a  substance,  rising  in  distilla- 
tion, which  not  a  little  resembled  naphthaline. 


412  MIXED  GASES. 

and  that  the  most  deplorable  accidents  have  frequently  resulted  from 
its  explosion.* 

(b.)  It  probably 'arises  from  the  decomposition  of  water  by  the 
coal,  and  issues  from  the  crevices  of  the  rocks  and  of  the  coal  strata, 
particularly  from  places  called  blowers  ;f  it  is  but  little  more  than 
half  as  heavy  as  common  air,  and  therefore  it  occupies  first  the  roof 
of  the  mine.f 

2.  HISTORY. 

(c.)  The  first  scientific  account  of  the  gas  of  coal  mines,  was  pub- 
lished in  1806,  by  Dr.  Henry, $  who  proved  that  it  is  the  same  as 
the  light  carburetted  hydrogen. 

(d.)  Sir  Humphrey  Davy,  some  years  later,  visited  the  coal  mines 
in  person,  descended  with  the  miners  into  the  regions  of  the  fire 
damp,  obtained  specimens  of  the  gas  and  subjected  them  to  a  chem- 
ical examination.  || 

(e.)  He  discovered  several  important  facts,  and  by  a  train  of  in- 
genious and  philosophical  reasoning,  was  led  to  a  happy  conclusion 
in  the  discovery  of  the  safety  lamp. 


*  In  the  Felling  Colliery,  92  miners  perished  at  one  time,  and  23  at  another,  and 
in  another  57  were  killed  in  the  same  way. — Murray. 

t  These  are  fissures  laid  open  in  working  the  mines. 

t  When  mixed  with  the  air  of  the  mine,  it  is  said  to  produce  a  misty  appearance, 
as  I  had  opportunity  of  observing  at  the  mines  of  Newcastle,  in  England,  in  Nov.  1805. 
If  the  quantity  of  gas  in  the  mines  is  small,  it  is  harmless;  but  if  great  the  consequences 
are  sometimes  extensively  fatal.  The  catastrophe  proceeds  from  the  extreme  in- 
flammability of  this  gas,  and  its  disposition  to  explode  when  mixed  with  the  atmos- 
phere. Unhappily,  in  these  dark  regions,  no  work  can  be  done  without  artificial 
light.  In  some  places,  they  work  by  the  feeble  sparks  produced  by  rubbing  flint 
against  a  jagged  steel  wheel.  In  other  places,  they  carry  a  candle  or  a  torch,  and 
whenever  the  fire  is  communicated  to  a  large  quantity  of  this  gas  mixed  with 
common  air,  the  explosion  is  as  sudden  and  violent  as  that  of  gun  powder.  Some- 
times, the  mine,  machinery,  and  miners  are  blown  up,  with  the  loss  of  all  their 
works,  and  of  course  of  the  lives  of  a  large  proportion  of  the  people. 

If  the  walls  and  roof  of  the  mine  are  so  strong  as  not  to  give  way,  the  expansive 
force  of  the  steam  and  of  the  elastic  vapors  rarefied  by  the  sudden  heat,  forces  every 
thing  along  the  narrow  chamber  of  the  mine,  as  a  bullet  is  driven  from  a  gun.  In 
the  mines  where  the  production  of  this  gas  is  not  very  rapid,  the  miners  set  fire  to  it 
frequently,  and  thus  explode  it  in  small  quantities  without  danger.  This  they  do  by 
means  of  a  candle  tied  to  the  end  of  a  long  pole,  which  they  elevate  into  those  parts  of 
the  roof  where  the  gas  commonly  collects.  Sometimes  they  tie  a  candle  in  the  mid- 
dle of  a  rope,  and  two  men,  by  pulling  the  rope  at  the  two  ends,  bring  the  candle 
into  contact  with  the  gas.  But  where  it  is  produced  too  copiously  to  be  managed  in 
this  way,  the  miners  fix  wooden  pipes  all  along  the  roof  of  the  mine,  with  branches 
carefully  communicating  with  those  places  from  which  the  gas  issues,  and  all  these 
pipes  are  connected  with  one  main  shaft  which  terminates  in  a  chamber  where  is  a 
fire  place  with  a  very  tall  chimney.  Here  a  fire  is  constantly  maintained,  and  the 
rarefaction  of  the  air  produces  a  constant  stream  from  all  parts  of  the  mine  to  this 
spot,  where  the  gas  burns  quietly  away  without  injury. 

When  the  inflammable  air  is  very  copious,  it  is  said  to  burn  at  the  top  of  the  chim- 
ney, and  to  produce  heat  enough  to  maintain  the  combustion  without  any  additional 
fael.  §  Nichok?on's  Jour.  XIX,  149. 

||  Phil.  Trans.  1816;  History  of  the  Safety  Lamp,  1818;  Phil.  Mag.  I,  50.  387. 


MIXED  GASES.  413 

3.  SOME  PECULIAR  PROPERTIES  OF  THE  FIRE  DAMP. 

(a.)  The  most  explosive  mixture  of  this  gas  with  common  air ',  was 
found  to  be  1  measure  of  the  inflammable  gas  to  7  or  8  of  air  ;  it  ex- 
plodes feebly  with  5  or  6  volumes  of  air,  and  with  only  3  or  4,  it  does 
not  explode  at  all ;  it  is  still  explosive  with  14  volumes  of  air,  but 
with  more,  a  taper  burns  in  it  only  with  an  enlarged  flame. 

(6.)  Charcoal  in  active  combustion,  and  iron  heated  to  redness  or 
even  to  whiteness,  did  not  kindle  this  mixture  ;  it  was,  however,  ex- 
ploded by  iron  in  a  state  of  brilliant  combustion,  and  the  smallest 
point  of  flame,  owing  to  its  high  temperature,  produced  instant  ex- 
plosion. 

(c.)  The  fact  which  led  immediately  to  the  discovery  of  the  safe- 
ty lamp,  had  been  observed  before  by  Dr.  Wollaston,  and  was  this, 
"  that  an  explosive  mixture  cannot  be  kindled  in  a  glass  tube  so  nar- 
row as  one  seventh  of  an  inch  in  diameter." 

(d.)  Two  separate  reservoirs  filled  with  an  explosive  mixture,  be- 
^ing  connected  by  a  metallic  tube  one  sixth  of  an  inch  in  diameter, 
a*nd  one  and  a  half  inch  in  length — the  explosion  could  not  be  made 
to  pass  into  the  one,  when  the  other  was  set  on  fire. 

(e.)  It  was  also  discovered  that  fine  wire  sieves,  or  wire  gauze 
being  in  fact  only  short  tubes,  form,  upon  the  same  principle,  an  effec- 
tual barrier  between  two  portions  of  explosive  gas,  which  will  not 
communicate  through  such  a  partition. 

(/.)  It  was  found  also  that  "  a  mixture  of  fire  damp  and  air,  in  ex- 
plosive proportions,  was  deprived  of  its  power  of  exploding  by  the 
addition  of  about  one  seventh  of  its  bulk  of  carbonic  acid  or  nitrogen 
gas."* 

(g.)  Sir  Humphry  Davy  was  thus  led  to  an  attempt  to  combine 
both  these  principles  by  the  construction  of  a  lamp,  which  being  fed 
with  only  a  limited  supply  of  air,  might  be  occupied  more  or  less  by 
carbonic  acid  and  nitrogen,  and  which,  by  having  small  metallic  aper- 
tures, might  prevent  the  spreading  of  combustion  into  the  surround- 
ing atmosphere,  should  that  be  in  an  inflammable  or  explosive  state. 

(A.)  After  various  modifications  and  improvements,  the  safety  lamp 
is  now  constructed  of  wire  gauze,  that  is,  the  flame  is  surrounded  by 
a  wire  sieve,  so  fine  as  to  have  at  least  625  apertures  in  a  square 
inch. 

(i.)  It  is  a  cylinder  2  inches  in  diameter  ;  it  rises  10  or  12  inches 
above  the  flame ;  the  wire  gauze  is  double  at  the  top,  where  the 
greatest  heat  exists,  and  no  part  of  it  is  impervious  to  air,  except 
that  which  contains  the  oil,  and  which  is  furnished  with  means  of 


*  Many  miners  perish  from  the  prevalence  of  these  gases  after  the   explosion  ; 
carbonic  acid  being  formed  and  mixed  with  the  nitrogen  which  is  left. 


414  SAFETY  LAMP. 

raising  and  trimming  the  wick,  and  recruiting  the  oil,  without  open- 
ing the  lamp  in  the  explosive  atmosphere. 

0*0  When  the  proportion  of  the  fire  damp  in  the  air  is  T'¥  the 
wick  of  the  lamp  is  seen  surrounded  by  a  faint  blue  flame. 

(k.)  When  the  proportion  is  increased  to  |,  j,  or  j,  the  lantern 
is  filled  with  the  flame,  burning  green,  as  I  have  observed  it  in  labo- 
tory  experiments ;  still,  the  flame,  even  when  the  wire  is  red  hot, 
does  not  communicate  to  the  exterior  air,  although  it  should  be  in  an 
explosive  state.* 

(I.)  Should  danger  arise  from  a  current  of  explosive  gas  passing 
through  so  rapidly  as  to  heat  the  wire  to  such  a  degree  that  it  might 
inflame  the  air ;  still  the  increase  of  the  cooling  surface,  either  by  di- 
minishing the  size  or  increasing  the  number  of  the  apertures,  would 
obviate  the  danger,  for  the  safety  of  the  instrument  is  supposed  to 
consist  in  the  cooling  powers  of  the  wire,  reducing  the  explosive 
gas  below  that  temperature  at  which  it  is  inflammable,  which  tem- 
perature is  stated  to  be  far  above  a  white  heat.f 

(m.)  Even  when  the-  noxious  gases  prevail,  so  as  to  extinguish 
the  lamp,  and  thus  threaten  life  by  suffocation,  a  small  coil  of  plati- 
num wire,  hung  above  the  lamp,  within  the  wire  gauze  cylinder,  will 
continue  to  glow,  and  will  enable  the  miner  to  grope  his  way  through 
regions  otherwise  perfectly  dark.  This  combustion  is  owing  to  the  fire 
damp,  but  it  does  not  communicate  to  the  external  air ;  and  on  com- 
ing into  better  air,  the  lamp  will  frequently  be  rekindled  spontaneously. 

*  The  miner  should,  however,  then  withdraw,  because  the  wire  may  be  so  rapidly 
oxidized  as  to  fall  to  pieces,  and  he  may  be  in  danger  also  of  suffocation,  from  the 
prevalence  of  irrespirable  gases. 

t  Sir  H.  Davy's  theory  of  the  safety  lamp  is  called  in  question  by  M.  G.  Sibri, 
(Bib.  Univ.  Mars,  1827,  and  Am.  Jour.  Vol.  XIII,  p.  179.)  who  contends  that  it  is 
not  owing  to  the  cooling  power  of  the  metal,  but  to  a  repulsion  existing  between 
flame,  and  any  substance  that  may  be  brought  near  it.  It  is  repelled  equally  by  a 
rod  of  glass  or  porcelain,  as  by  one  of  metal,  and  the  effect  depends  not  on  the  nature 
of  the  body,  but  is  proportioned  directly  to  its  bulk,  and  inversely  to  its  distance  ; 
even  two  flames  will  repel  each  other,  and  so  gross  a  flame  as  that  of  a  candle,  will 
refuse  to  pass  between  two  rods  of  any  kind,  (even  wood,)  brought  near  to  each  other 
on  opposite  sides  of  the  flame,  and  near  the  summit.  The  repulsion  is  not  all  affect- 
ed by  the  temperature  of  the  substance.  I  have  repeated  these  experiments,  and 
find  them  exact,  and  the  cause  is  obvious ;  the  repulsion  appears  to  be  occasioned  by 
the  gas,  which  is  incessantly  blowing  out  from  flame,  and  which  striking  against  any 
obstacle,  reacts,  to  inflect  the  flame  ;  just  as  a  current  of  lava  will  sometimes  stop 
short,  at  a  wall,  rise  parallel  to,  and  finally  cascade  over  it,  without  touching  it ;  this 
well  ascertaained  fact  is  owing  to  the  great  quantity  of  ae'rial  matter  blown  out  by 
lava,  and  which,  meeting  with  an  obstacle,  reacts  upon  it  as  above  described,  with 
respect  to  flame.  Mr.  Sibri  conceives  that  the  number  of  wires  in  the  metallic 
gauze  of  the  safety  lamp,  is  by  far  too  great,  and  that  the  same  security  would  be  af- 
forded by  such  a  number  as  would  merely  give  strengh  to  the  instrument,  without 
so  much  impeding  the  light.  I  have  never  felt  satisfied  with  this  part  of  the  theory 
of  the  safety  lamp,  given  by  its  illustrious  inventor,  and  am  disposed  to  think  that 
the  one  suggested  above  is  the  principal  source  of  protection  ;  in  this  opinion  I  am 
supported  by  Prof.  J.  Griscom,  to  whom  I  am  indebted  for  the  notice  of  Mr.  Sibris' 


SAFETY  LAMP. 


415 


A,  is  a  large  bell  of  common  air,  held  by 
the  hand,  or  suspended  by  a  string. 

B,  is  a  lighted  safety  lamp,  held  by  an  as- 
sistant within  the  jar. 

C,  An  air  jar,  with  cap,  stop  cock,  and 
tube,  filled  with  carburetted  hydrogen,  and 
depressed  into  the  water  of  the  pneumatic 
cistern,  D  D,  so  that  by  gently  turning  the 
key^*,  the  inflammable   gas  flows  through 
the  tube,  mixes  with  atmospheric  air,  pene- 
trates the  lamp,  and  enlarges  the  flame  ;  it 
even  fills  the  whole  lamp  with  a  delicate 
blue  or  green  flame,  which  ultimately  ex- 
tinguishes the  light  of  the  lamp  ;  but  if, 
when  the  lamp  is  nearly  extinguished,  it  be 
lowered  a  little,  so  as  to  better  the  condi- 
tion of  the  air,  it  will  be  rekindled,  and 
then  may  again  be  raised  into  the  jar,  and 
so  on. —  Comm. 

Figure  and  Description  from  Dr. 

"  The  lamp  is  seen  within 
a  large  glass  cylinder  upon  a 
stool.  The  cylinder  is  close- 
ly covered  by  a  lid,  which 
will  not  permit  the  passage  of 
air  between  it  and  the  cylin- 
der, and  which  is  so  light  as 
to  be  easily  blown  off.  Ex- 
cepting the  cage  alluded  to 
above,  the  safety  lamp  differs 
not  materially  from  those 
which  are  ordinarily  used. 
The  upper  surface  of  the  re- 
ceptacle for  the  oil,  forms  the 
bottom  of  the  cage,  which  is 
so  closely  fitted  to  it,  and  so 
well  closed  every  where,  as 
to  allow  air  to  have  access  to 
the  flame  only  through  the 
meshes  of  the  wire  gauze. 
The  cage  is  enclosed  within 
three  iron  rods,  surmounted 
by  a  cap,  to  which  a  ring  for 
holding  the  lamp  is  attached, 
as  seen  in  the  drawing." 

"  If  while  the  lamp  is  burn- 
in  £,  as  represented  in  the 


Hare. 


416  SAFETY  LAMP. 

figure,  hydrogen,  either  pure  or  carburetted,  be  allowed,  by  means 
of  the  pipe,  to  enter  the  glass  cylinder,  so  as  to  form  with  the  air  in 
it  an  explosive  mixture,  there  will,  nevertheless,  be  no  explosion.  It 
will  be  found  that  as  the  quantity  of  inflammable  gas  increases,  the 
flame  of  the  lamp  enlarges,  until  it  reaches  the  wire  gauze,  where  it 
burns  more  or  less  actively,  according  as  the  supply  of  atmospheric 
air  is  greater  or  less.  It  will,  under  these  circumstances,  often  ap- 
pear as  if  the  combustion  had  ceased,  but  on  increasing  the  propor- 
tion of  atmospheric  air,  the  flame  will  gradually  contract,  and  finally 
settle  upon  the  wick,  which  will  burn  as  at  first,  when  the  supply  of 
hydrogen  ceases." 

"If  the  cage  be  removed  from  the  lamp,  and  the  experiment  repeat- 
ed in  all  other  respects  as  at  first,  an  explosion  will  ensue,  as  soon  as 
a  sufficient  quantity  of  hydrogen  is  allowed  to  enter  the  cylinder." 

It  appears  that  Mr.  Stevenson  invented  a  lamp,  whose  light  was 
enclosed  in  a  lantern,  to  which  air  was  admitted  by  a  number  of 
tubes,  and  any  explosion  within  did  not  communicate  to  the  air  with- 
out. 

The  principal  inconveniences  of  Sir  H.  Davy's  lamp  are,  its  lia- 
bility to  injury,  on  account  of  its  delicate  texture,  and  if  there  is  a  hole 
made  in  it,  the  explosive  atmosphere  without  may  be  readily  fired  ;  it 
is  evident  also  that  it  does  not  afford  a  strong  light,  and  the  work- 
men are  sometimes  tempted  if  possible,  to  open  it,  even  in  dangerous 
situations,  and  accidents  are  said  to  have  occurred  from  that  cause. 
Dr.  Murray  invented  a  safety  lamp,  of  which  an  account  is  given  by 
his  son,*  founded  upon  the  well  known  fact,  that  the  inflammable 
gas  occupies  principally  the  upper  cavities,  and  that  the  air  on  the 
floor  is  ordinarily  good.  The  air  for  the  support  of  the  flame  is 
drawn  from  the  floor,  by  a  flexible  tube,  passing  from  the  bottom  of 
the  lamp,  while  the  chimney  at  the  top,  by  the  strong  current  which 
it  is  constantly  discharging,  prevents  the  entrance  of  gas  from  that 
direction.  The  lamp  is  also  of  sufficient  strength,  and  being  furnish- 
ed with  a  good  mirror  and  lens,  it  throws  a  strong  light,  and  it  is 
said  that  if  an  explosion  should  happen  in  it,  it  would  merely  extin- 
guish the  light,  but  would  not  extend  to  the  atmosphere  without. f 


*  Elements,  6th  Ed.  Vol.  I,  p.  609. 

t  Trans.  Roy.  8oc.  Edin.  Vol.  VI,  p,  31. 


CYANOGEN.  417 


COMPOUND  OF  NITROGEN  AND  CARBON. 

This  compound  is  named  here,  because,  in  the  strictness  of  logi- 
cal arrangement,  this  is  the  place  for  its  introduction  ;  but  its  fuller 
developement,  and  that  of  the  connected  topics,  will  be  reserved  to 
a  more  advanced  stage  of  this  work,  because  the  subject  is  compli- 
cated and  difficult,  and  requires  the  previous  knowledge  of  the  most 
important  facts  of  elementary  chemistry.  These  topics  will  be 
touched  upon  again  under  iron,  and  the  other  metals,  and  finished 
under  the  chemistry  of  animal  bodies,  from  which  the  principal 
agents  of  this  family  are  derived. 

CYANOGEN. 

1.  NAME. — xuavo^,  blue.* 

2.  PROCESS. — If  prussian  blue,  8  parts,  be  boiled  with  red  oxide 
of  mercury,  1 1  parts,  a  crystallizable  salt  will  be  obtained,  the  prus- 
siate  or  cyanuret  of  mercury,  by  heating  which,  in  a  dry  state,  in  a 
retort,  we  obtain  over  mercury  a  gas  called  cyanogen,  which  burns 
with  a  superb  purple  and  violet  flame.     It  is  composed  of  2  equiva- 
lents of  carbon,  and  1  of  nitrogen. 

PRUSSIC    ACID,    OR    HYDRO-CYANIC  ACID. 

1.  NAME. — Called  prussic  acid,   from  prussian  blue,  the  parent 
substance,  from  which,  as  above,  the  cyanuret  or  prussiate  of  mercury 
is  obtained,  which  affords  this  agent.     The  term,  hydro-cyanic,  refers 
to  the  union  of  hydrogen  with  cyanogen,  to  form  this  acid. 

2.  PROCESS. — Decompose  the  prussiate,  or  cyanuret  of  mercury, 
in  a  retort  by  muriatic  acid,  and  condense  the  volatile  product  in  an 
ice  cold  receiver. 

3.  PROPERTIES. — It  is  the  most  diffusive  and    virulent  poison 
known  ;  it  kills  small  animals  when  a  drop  is  applied  to  the  tongue, 
and  a  few  drops  are  more  than  sufficient  to  extinguish  life  in  a  vigor- 
ous man.     It  exists  ready  formed  in  the   vegetable    kingdom,    in 
peach  blossoms,  and  peach  kernels,  in  the  bitter  almond,  in  the  lauro 
cerasus,  &ic.     It,  or  its  radical,   combines  with  alkaline  and  earthy 
bases,  and  the  prussiates  or  cyanurets  of  these  bodies  furnish  us  with 
tests  that  are  highly  useful  in  detecting  the  metals.     The  prussic  prin- 
ciple is  transferred  to  them,  front  prussian  blue,  and  these  applications 
may  be  occasionally  mentioned  before  the  subject  is  fully  exhibited. 

There  are  two  acids  composed  of  cyanogen  and  oxygen,  call- 
ed, the  one  cyanic,  and  the  other  fulminic  acid  ;  and  one  of  them  is 
supposed  to  exist  inthe  fulminating  silver,  and  in  fulminating  mercury. 


In  allusion  to  Prussian  blue. 
53 


418  PHOSPHORUS. 

SEC.  IV. — PHOSPHORUS. 

1.  HISTORY  AND  NAME. 

(a.)  Brandt,  an  alchemist  of  Hamburgh,  has  the  credit  of  discov- 
ering Phosphorus,  A.  D.  1669,  while  endeavoring  to  transmute 
metals  ;*  Brandt  sold  the  secret  to  his  friend,  Kunckel,  but  deceiv- 
ed him  with  a  false  process.  Kunckel,  having  however  learned 
that  it  was  obtained  from  urine,  avenged  himself  by  making  the  dis- 
covery anew. 

Mr.  Boyle  also  discovered  it  in  England,  and  Godfrey  Hankwitz, 
a  man  instructed  by  him,  vended  it  at  a  high  price,  in  a  shop  still 
shown  in  London,  near  Covent  Garden  Theatre. 

(b.)  In  1737,  a  committee  of  the  French  Academy  of  Sciences  was 
instructed  in  the  process  by  a  stranger  ;  it  was  then,  as  at  first,  ob- 
tained by  evaporating  bogheads  of  putrid  urine  to  dryness,  and  after- 
wards distilling  the  residuum  with  a  strong  heat,  in  a  stone  ware  retort. 

(c.)  JVLargrajf,  of  Berlin,  by  adding  muriate  of  lead  to  tlie  urine, 
precipitated  phosphoric  acid,  in  union  with  oxide  of  lead,  and  this 
was  decomposed  by  distillation  with  charcoal. 

(d.)  In  1769,  Ghan,  of  Sweden,  a  pupil  of  Scheele,  having  dis- 
covered that  phosphate  of  lime  is  the  basis  of  bones,  invented  the  pro- 
cess now  generally  followed. 

The  name  signifies  light  bearer,  $£5  <Npw. 

2.  PREPARATION. 

(a.)  Obtained  from  bones,  by  a  process  to  be  described  under 
phosphate  of  lime. — At  the  same  time  may  be  mentioned,  the  pro- 
cesses by  which  it  is  extracted  from  urine,  and  from  the  phosphates  of 
soda  and  ammonia,  and  the  method  of  purification  ;  but,  for  the  pres- 
ent, we  will  consider  it  as  obtained  and  pure. 

3.  PROPERTIES. 

(a.)  Color,  after  distillation  in  hydrogen,  nearly  white,  and 
semi-transparent,  usually  however,  brownish  or  flesh  red  ;  looks  like 
wax — is  insipid — becomes  black  when  suddenly  cooled,  after  being 
heated  to  140°  or  160°  ;  but  cooled  slowly,  remains  transparent 
and  colorless,  or  with  the  translucence  of  horn.  Thenard  says  that 
it  must  have  undergone  repeated  distillations,  in  order  to  exhibit 
these  appearances. 

(b.)  Solid,  brittle  in  cold  weaihet* ;  fracture  sometimes  radiated ; 
sp.  gr.  1.714,  or  1.77  ;  in  mild  weather  easily  cut;  in  cold  weather 
brittle.f 


*  He  imagined  that  the  extract  of  urine,  would  enable  him  to  transmute  the  baser 
metals  into  gold  and  silver,  and  while  heating  this  substance,  the  phosphorus  was 
evolved.  t  If  pure,  it  is  very  flexible  ;  l-600th  of  sulphur  renders  it  brittle. 


PHOSPHORUS.  419 

(c.)  Crystallizes  by  melting  it  under  water,  and  when  the  crust 
has  congealed,  it  must  be  pierced,  and  the  liquid  interior  poured  out, 
by  inclining  the  vessel ;  the  crystals  are  needles,  or,  if  the  cooling 
has  been  slow,  octahedra.* 

(d.)  Crystallizes  also  from  solution  in  an  essential  oil,  by  slow 
evaporation,  and  in  dodecahedra,  from  solution  of  phosphuret  of  sul- 
phur. 

( e.)  Becomes  covered  with  a  brownish  crust,  by  keeping. 

(/.)  Melts  at  99°,  and  this  must  be  done  always  under  water 
Volatilized  at  219°,  boils  in  close  vessels  at  554°,  takes  fire  in  the 
air,  at  148°.f 

(g.)  Highly  inflammable,  and  burns  with  a  bright  white  flame,  and 
much  white  smoke,  which  if  collected  is  found  to  be  acid. 

(A.)  It  burns  with  intense  splendor  in  oxygen  gas,  but  the  facts  on 
this  head  are  reserved  for  phosphoric  acid.  It  burns  also  in  chlo- 
rine and  other  gases,  to  be  mentioned  in  their  proper  places. f 

(i.)  Burns  slowly  without  flame ;  in  the  dark,  with  a  beautiful 
blue  luminous  cloud,  and  with  a  white  smoke  in  the  light ;  but  not 
in  air  artificially  dried ;  these  appearances  are  more  distinct,  in  pro- 
portion as  the  temperature  is  higher,  and  a  garlic  smell  accompanies 
them.  Mr.  Boyle  found  that  3  grains  emitted  light  for  15  days. 

(/.)  A  stick  of  phosphorus,  placed  in  a  glass  tube,  for  a  handle, 
will  leave  luminous  traces,  if  drawn  on  a  wall  in  a  dark  room,  but  it 
does  not  show  well  unless  in  a  warm  place ;  in  the  cold,  it  is  not  ap- 
parent. 

(k.)  Jl  piece  of  phosphorus,  between  two  folds  of  paper,  is  easily  in- 
flamed by  friction. 

(I.)  By  means  of  a  little  tallow  or  wax,  stick  some  phosphorus 
to  the  side  of  a  wine  glass,  or  tumbler,  and  it  may  be  inflamed  by  mix- 
ing sulphuric  acid  and  water,  in  the  vessel. 

(m.)  Phosphorus  merely  luminous  does  not  burn  the  fingers,  still  it 
is  best  always  to  take  hold  of  it  with  forceps. 

(n.)  Phosphoric  fire  bottles  are  formed  by  putting  very  dry  phos- 
phorus into  a  dry  vial  with  a  small  mouth,  and  then  introducing  a  hot 
iron  rod  and  rolling  the  vial  upon  it  as  an  axis ;  it  must  be  corked  as 
soon  as  the  iron  is  withdrawn. 


*  By  melting  and  cooling  large  quantities  under  water,  it  has  been  obtained  in  oc- 
tahedral crystals  of  the  size  of  cherry  stones. 

t  According  to  Higgins,  if  quite  dry  it  takes  fire  at  60°.  most  authors  say  108°, 
or  109. 

t  Mr.  Graham  has  observed  that  its  combustion  is  prevented  by  the  presence  of 
very  small  quantities  of  foreign  gases  and  vapors,  as  l-450th  defiant,  l-150th  etherial 
vapor,  l-1820th  vapor  of  naptha,  l-4444th  of  that  of  oil  of  turpentine,  &c. — Turner. 


420 


PHOSPHORUS. 


(o.)  The  same  thing  is  less  perfectly  done  by  simply  melting  the 
phosphorus  in  the  vial  and  then  corking  and  rolling  it  around,  that  the 
phosphorus  may  adhere  to  every  part. 

(p.)  A  sulphur  match  is  to  be  introduced  and  rapidly  withdrawn, 
rubbing  at  the  same  time  against  the  side ;  if  it  does  not  fire,  a  little 
friction  on  a  board  or  a  cork  will  generally  make  it  burn.* 

(q.)  Eudiometry  is  performed  by  phosphorus,  by  rapid  combustion 
and  by  slow,  in  various  ways.f 

ATMOSPHERIC  EUDIOMETER,  BY  PHOSPHORUS. Dr.  Hare. 

"  If  a  cylinder  of  phosphorus  be  support- 
ed upon  a  wire  (as  here  represented)  within 
a  glass  matrass,  inverted  in  a  jar  of  water, 
the  oxygen  of  the  included  air  is  gradually 
absorbed.  In  order  to  determine  the  quan- 
tity of  oxygen  in  the  air,  we  have  only  to 
ascertain  the  ratio  between  the  quantity  ab- 
sorbed, and  the  quantity  included. 

"  This  object  may  be  attained  by  weigh- 
ing the  matrass,  when  full  of  water,  and 
when  containing  that  portion  only  which 
rises  into  it  in  consequence  of  the  absorp- 
tion. As  the  weight  in  the  first  case  is  to 
the  weight  in  the  last,  deducting  the  weight 
of  the  glass  in  both  cases,  so  will  100  be  to 
the  number  of  parts,  in  100  of  atmospheric 
3ir,  which  consist  of  oxygen  gas. 


*  A  spontaneous  light  is  formed,  by  inserting  a  taper  with  a  bit  of  phosporus  on  the 
wick,  into  a  tube  sealed  and  drawn  thin  at  the  end  next  the  phosphorus;  the  other 
end  maybe  sealed  or  not;  the  phosphoric  end  is  heated  in  the  mouth  or  otherwise, 
and  withdrawn  suddenly,  or  the  tube  is  broken  when  the  phosphorus  fires — it  is  a  toy. 

J  Eudiometer  of  Seguin. — Fill  with  and  invert  in  mercury,  a  glass  tube  one  inch 
in  diameter  and  ten  inches  long;  throw  up  a  small  piece  of  phosphorus;  it  is  then 
melted  by  a  live  coal  or  hot  iron,  and  small  portions  of  a  measured  quantity  of  air 
are  separately  introduced ;  the  phosphorus  is  inflamed  each  time ;  heat  the  top  of 
the  tube  at  finishing,  and  measure  the  residuum  which  is  nitrogen. 

Huniboldfs. — Introduce  phosphorus,  1  grain  to  12  cubic  inches  of  air,  into  a  grad- 
uated tube,  hermetically  sealed  at  one  end,  and  carefully  corked  at  the  other.  In- 
flame it  by  a  coal,  and  after  all  is  cool  the  cork  is  withdrawn  under  water;  the 
space  unoccupied  by  the  water  is  nitrogen  gas. 

JBerthollefs. — In  this  there  is  a  slow  combustion,  in  a  graduated  glass  tube.  A 
measured  quantity  of  air  is  thrown  up,  and  a  slick  of  phosphorus,  supported  on  a 
glass  rod,  is  made  to  pervade  it.  In  a  few  days  the  oxygen  gas  will  be  absorbed, 
and  an  acid  formed  which  will  be  absorbed  by  the  water,  while  the  nitrogen  is  left. 
Nitrogen  gas  dissolves  a  little  phosphorus,  and  is  thereby  augmented  in  bulk 
£bout  one  fortieth,  which  must  be  in  each  case  subtracted. 


PHOSPHORUS.  421 

"  If  the  neck  of  a  vessel  of  this  kind  hold  about  one  fourth  as  much 
as  the  bulb,  by  graduating  the  neck,  so  that  each  division  will  repre- 
sent a  hundredth  part  of  the  whole  capacity,  the  result  may  be  known 
by  inspection."* 

(r.)  Phosphorus  is  not  luminous  in  oxygen  gas,  and  does  not  burn 
in  it  even  slowly,  nor  can  any  light  be  perceived  in  the  darkest 
place,  till  the  temperature  is  raised  to  80°  or  81°,  which,  if  the 
vessel  is  small,  may  be  done  by  warming  it  by  the  hands. 

(s.)  It  then  becomes  luminous,  and  is  surrounded  by  white  vapors  ; 
this  appearance  ceases  again  if  the  temperature  sink  to  55° ;  at  about 
104°  it  takes  fire  in  oxygen  gas;  though  not  luminous  at  55°,  it  ap- 
pears to  be  dissolved  slowly  in  the  oxygen  between  that  degree  and 
81°. 

(t.)  If  into  oxygen  gas  thus  impregnated  with  phosphorus,  nitrogen 
or  hydrogen  be  thrown  up,  it  becomes  luminous. 

(u.)  Nitrogen  dissolves  phosphorus  from  55°  upward,  and  it  may 
be  distilled  in  this  gas  or  in  hydrogen,  and  it  does  not  become  lu- 
minous. 

(v.)  But  a  bubble  or  two  of  oxygen  gas  or  common  air,  or  any 
gas  mixed  with  oxygen,  renders  the  nitrogen  luminous. 

(w.)  More  strikingly  still  if  phosphorized  nitrogen  be  let  up  into 
such  gases  ;  pure  oxygen  is  however  best  of  all. 

(x.)  Phosphorus  becomes  luminous  in  common  air,  whose  pres- 
sure is  diminished  to  one  eighth  or  one  tenth  that  of  the  atmosphere. 

(y.)  Phosphorized  nitrogen  and  phosphorized  oxygen,  (made  by 
keeping  both  gases  in  contact  with  phosphorus  for  some  hours,)  do 
not  become  luminous  when  mixed  at  55°. 

(z.)  Phosphorus  is  easily  dissolved,  by  simple  digestion  in  oil  of 
olives,  almonds,  &tc. 

(aa.)  Also,  in  oil  of  turpentine  and  other  essential  oils,  but  more 
care  is  necessary. 

(bb.)  Phosphorized  oils  rubbed  on  the  face  and  hands,f  or  poured 
into  hot  water,  exhibit  luminous  clouds  and  flashes. 

(cc.)  Phosphorus  dissolves  in  alcohol  with  a  gentle  heat,  but  the 
experiment  is  dangerous,  as  the  vial  must  be  corked  ;  it  must  there- 
fore be  very  strong,  and  the  heat  applied  very  gentle. 

(dd.)  A  flash  of  light  appears  when  this  spirit  is  poured  upon  hot 
water  in  the  dark. 

4.  ELEMENTARY  NATURE  OF  PHOSPHORUS. — Sir  Humphry  Davy, 
by  galvanizing  phosphorus  in  a  glass  tube,  with  a  battery  of  500  pairs 


*  For  a  more  precise  eudiometer  see  Dr.  Hare's  Compendium,  p.  170. 
t  It  should  be  ascertained  that  the  phosphorus  is  all  dissolved ;  otherwise  severe 
burns  may  be  produced. 


422  PHOSPHORIC  ACID. 

of  plates,  extricated  a  considerable  quantity  of  phosphuretted  hydro- 
gen^ and  caused  the  phosphorus  to  become  of  a  deep  red  brown  color. 
It  is  not,  however,  considered  as  certain  that  hydrogen  is  contained 
in  phosphorus ;  it  may,  in  this  case,  have  proceeded  from  moisture 
accidentally  present,  for  a  little  moisture  would  afford  a  large  vol- 
ume of  hydrogen  gas,  which  would  of  course  be  phosphorized. 

5.  POLARITY. — Phosphorus  is  attracted  by  the  negative  pole  in  the 
galvanic  circuit,  and  is  therefore  electro-positive. 

6.  COMBINING  WEIGHT,  12. 

7.  MISCELLANEOUS. — Phosphorus  exists  no  where  in  nature  in  a 
free  state  ;  this  would  be  impossible  on  account  of  its  combustibility. 
It  is  found  in  the  acid  of  the  natural  phosphates  of  lead,  copper,  iron, 
lime,  &tc. ;  most  abundantly,  however,  in  animal  bodies,  and  more 
particularly  in  bones.     It  exists  also  in  the  saline  form,  in  vegetable 
fluids.     Phosphorus  is  little  used  except  in  the  laboratory.     It  is  a 
violent  poison,  even  as  is  said,  in  the  dose  of  1  grain.     In  more 
moderate  doses,  it  is  stimulating,  antispasmodic,  &c.     Its  best  form 
of  exhibition  is,  dissolved  in  ether,  8  grs.  to  1  oz.  of  which  4  or  5 
drops  containing  about  TV   of  a  gr.  may  be  given  two,  three,  or 
more  times  in  a  day,  in  some  spirituous  tincture. —  Coxe. 

PHOSPHORIC  ACID. 

1.  HISTORY. — Not  known  till  after  the  discovery  of  phosphorus; 
observed  by  Boyle  ;  first  examined  by  Margraff. 

2.  PREPARATION. 

(a.)  By  decomposing  bone  ashes  by  sulphuric  acid,  for  the  particu- 
lars of  which  process,  see  phosphate  of  lime. 

(b.)  By  the  combustion  of  phosphorus. — Phosphorus  burning  in  an 
earthen  dish  floating  on  mercury  is  covered  by  a  bell  glass  full  of 
common  air  or  oxygen  gas.*  The  combustion  in  the  latter,  is  rapid 
and  brilliant,  with  much  heat  and  light ;  the  phosphorus  with  the  oxy- 
gen is  converted  into  phosphoric  acid,  which,  jn  a  diy  vessel,  is  con- 
densed in  white  flakes ;  the  gas,  if  pure  and  in  proper  proportion, 
wholly  disappears,  and  any  foreign  gas  remains.  There  should  be 
an  excess  of  oxygen  gas,  to  save  the  vessels  from  fracture  ;  if  the 
oxygen  is  pure  at  first,  the  remaining  gas  is  still  so. 


*  500  grs.  of  phosphorus  require  1  cubic  foot  of  oxygen  gas  at  a  medium  tempera- 
ture for  saturation,  and  the  product  is  1250  grs.  dry  phosphoric  acid;  1  grain  of  phos- 
phorus requires  15  cubic  inches  of  common  air,  and  of  course  about  4  cubic  inches  of 
oxygen  for  its  saturation. — Note  Book.  Dr.  Hope's  Lectures,  Edinb. 


PHOSPHORIC  ACID.  493 

(c.)  This  combustion  is  elegantly  performed  in  a  glass*  globe,  of 
the  capacity  of  three  gallons,  with  a  mouth  two  or  three  inches  wide  ; 
a  concave  copper  dish  supported  by  wires  which  are  hooked  at  the 
top  so  as  to  hang  from  the  orifice,  contains  the  phosphorus  ;  a  piece 
not  larger  than  a  hazle  nut  should  be  employed  ;  the  dry  globe  is 
filled  with  oxygen  gas  flowing  from  a  gazometer  and  introduced  by 
a  tube  going  to  the  bottom  and  displacing  the  common  air. 

A  hot  iron  kindles  the  phosphorus,  and  a  saucer  is  laid  over  the 
orifice  ;  when  one  piece  of  phosphorus  is  burnt  out,  another  may  be 
introduced  through  a  glass  tube,  and  will  kindle  of  its  own  accord, 
and  so  on  till  the  oxygen  is  exhausted. 

This  experiment,  in  one  case,  yielded  me  distinct  crystals  of  perfectly 
transparent  phosphoric  acid,  scattered  in  great  numbers  in  the  interior 
of  the  glass  globe ;  they  were  not  larger  than  a  pin's  head,  and  were 
formed  from  the  viscous  fluid  arising  from  the  deliquescence  of  flakes 
of  concrete,  snow-white  phosphoric  acid  ;  when  the  air  is  admitted,  it 
deliquesces  in  a  few  minutes. 

(c?.)  The  above  experiment  is  neatly  performed  by  commencing 
the  combustion  in  a  glass  globe  in  common  air  or  in  oxygen  gas,  and 
allowing  the  last  to  flow  in  as  it  is  needed,  from  a  gazometer  through 
a  flexible  tube  ;  by  introducing  phosphorus  and  oxygen  gas,  alter- 
nately, the  experiment  may  be  safely  continued  as  long  as  we  please. 

(e.)  Melt  phosphorus  in  a  thin  glass  globe  underwater,  and  inject 
oxygen  gus  through  a  tube,  descending  to  the  bottom  of  the  vessel, 
and  connected  with  a  bladder  or  gazometer ;  as  the  gas,  by  small 
portions  at  a  time,  comes  in  contact  with  the  melted  phosphorus,  the 
latter  flashes  beautifully  under  the  water,  which  dissolves  the  acid 
thus  formed,  and  by  evaporation,  it  is  obtained  solid.f — Pelletier. 

(/.)  Drop  successively,  small  pieces  of  phosphorus  into  warm  nitric 
acid,$  diluted  with  an  equal  bulk  of  water,  contained  in  a  flask,  or 
tubulated  retort.  When  the  red  fumes  of  nitrous  acid  gas  cease, 
and  the  fresh  pieces  of  phosphorus  readily  take  fire  at  the  surface, 
the  process  is  through. 

By  continuing  the  heat,  any  remaining  acid  will  be  expelled,  and 
the  concrete  phosphoric  acid  obtained  ;  1  dr.  3  grs.  of  phosphorus, 


*  See  Lavoisier's  Elements,  and  Dr.  Hare's  Compendium,  p.  103,  for  an  appa- 
ratus admitting  of  accuracy,  in  consequence  of  the  use  of  the  air  pump. 

t  A  considerable  quantity  of  a  red  flaky  substance  floats  in  the  water,  which  some 
have  regarded  as  an  oxide  of  phosphorus. 

t  If  the  acid  be  concentrated,  there  will  be  a  rapid  inflammation,  and  if  the  pieces 
of  phosphorus  are  large,  there  may  be  even  a  dangerous  explosion. 

Some  writers  recommend  concentrated  acid  in  a  platinum  capsule:  this  will  ordi- 
narily induce  inflammation,  or  explosion,  with  some  danger  and  considerable  loss ; 
with  a  diluted  acid,  in  a  mattrass,  both  inconveniences  may  be  avoided.  I  have 
often  tried  both. 


424  PHOSPHORIC  ACID. 

with  3  oz.  of  the  common  acid,  produce  6  dr.  of  phosphoric  acid. 
The  theory  will  be  be  given  hereafter. 

3.  PROPERTIES. 

(a.)  Evaporated  and  heated  to  ignition  in  a  platinum  crucible,  it 
becomes  white,  firm  and  transparent,  like  glass.  This  is  the  pure 
acid.* 

(b.)  Deliquesces  into  a  jelly  ;  soluble  in  water,  the  anhydrous 
flakes  dissolve  with  hissing  ;  the  acid  decidedly  reddens  the  vegetable 
blues  ;  it  is  very  sour  and  almost  corrosive  ;  it  combines  with  bases 
to  form  phosphates.  It  blackens  oils. 

(c.)  The  glacial  phosphoric  acid  is  a  hydrate,  and  the  water  can 
not  be  expelled  by  heat,  for  if  fully  ignited,  it  rises  in  vapor  with  the 
water.  It  used  to  be  said  that  this  acid  is  fixed  at  intense  degrees 
of  heat ;  this  remark  applies  only  to  the  impure  acid ;  still  it  endures 
a  considerable  heat,  and  from  its  tendency  to  vitrify  with  earthy 
bodies,  it  is  a  powerful  flux,  and  is  very  effectual  in  decomposing 
saline  bodies,  provided  heat  be  applied. 

(d.)  The  deliquesced  acid,  on  being  heated  in  a  platinum  cruci- 
ble, exhibits  anew,  after  being  cooled,  the  density  and  brilliancy  of 
the  precious  stones. f 

(e.)  A  great  quantity  of  heat  and  light  are  liberated  during  the 
combustion,  which  unites  two  substances,  one  a  gas,  and  the  other  a 
volatile  odorous  solid ;  the  phosphoric  acid  is  inodorous  and  fixed, 
and  of  great  density,  which  implies  great  condensation.  The  dry 
acid  sublimes  in  close  vessels ;  a  little  water  prevents  this,  but  a  larger 
proportion  carries  up  some  of  the  acid  with  it  when  it  is  evaporated. 

(/.)  A  little  heat  is  evolved  when  phosphoric  acid  of  a  spongy 
consistency,  is  mixed  with  water ;  the  heat  has  varied  from  1°,  to 
more  than  50°,  as  the  density  of  the  acid  was  greater  or  less. 

(g.)  Sp.gr.  in  glass  2.8516;  in  dryness  2.687;  in  deliques- 
cence 1.417, 

(A.)  Charcoal,  at  a  red  heat,  completely  decomposes  the  phospho- 
ric acid ;  carbonic  acid  gas  is  formed  and  the  phosphorus  sublimes, 
and  may  be  received  by  immersing  the  neck  of  the  retort  under 
water.  This  is  nearly  the  ordinary  process  for  the  extraction  of  phos- 
phorus. 

(*".)  Diamond  produces  no  effect ;  for  it  may  be  kept  a  long  time 
in  the  midst  of  phosphoric  acid,  at  a  red  heat,  without  experiencing 


*  In  the  process  by  nitric  acid,  some  ammonia  is  formed  by  the  union  of  the  hy- 
drogen of  the  water  with  the  nitrogen  of  the  acid,  and  it  is  driven  off  by  the  heat. 

t  Chaptal  says,  "  I  observed  once,  to  my  great  astonishment,  that  the  phosphoric 
glass  I  had  just  made,  emitted  very  strong  electric  sparks ;  these  flew  to  the  hand 
at  the  distance  of  two  inches.  I  exhibited  this  phenomena  to  my  audience  of  pupils. 
This  glass  lost  the  property  in  two  or  three  days,  though  preserved  in  a  capsule  of 
common  glass." 


PHOSPHOROUS  ACIDS.  425 

any  change ;  owing,  without  doubt,  to  the  strong  cohesion  of  its 
particles.* 

(/.)  Phosphoric  acid  separates  the  carbonic,  with  effervescence, 
from  its  combinations. 

4.  COMPOSITION. — According  to  Lavoisier's  elaborate  experiments, 
related  in  his  Elements,  phosphoric  acid  is  composed  of  about  60 
parts  of  oxygen  to  40  of  phosphorus,  f  or  about  3  parts  of  the  former 
to  2  of  the  latter.     Other  and  more  recent  philosophers  give  less 
oxygen,  but  differ  in  their  results. 

Rose,  100  phosphorus  are  combined  with  114.6  oxygen. 

Dulong,        100         do.  do.  124.8       do. 

Berzelius,     100         do.  do.  127.5      do. 

Davy,  100         do.  do.  135.        do. 

Davy  formerly  obtained  153.  for  the  proportion  of  oxygen.  Dr. 
Henry  thinks  that  the  true -proportion  is  probably  133J.  The  com- 
bining weight  of  phosphorus  has  been  deduced  from  the  composi- 
tion of  phosphate  of  lead,  and  is  taken  at  12.J  and  that  of  phospho- 
ric acid,  adding  2  equivalents  of  oxygen,  16,  at  28. 

5.  POLARITY. — It  is  attracted  to  the  positive  pole,  and  is  therefore 
electro-negative. 

6.  USES. — A  powerful  acid,  not  known  in  common  life  nor  in  the 
arts.     Some  of  its  alkaline  salts  are  used  as  fluxes. 

7.  DISTINCTIVE  CHARACTER. — The  solid  phosphoric  acid,  heated 
on  charcoal  by  the  blowpipe,  exhibits  a  flame,  proceeding  from  the 
decomposition  of  the  acid  by  the  coal  and  the  consequent  emission 
and  combustion  of  phosphorus. 

PHOSPHOROUS  ACIDS. 

1.  HISTORY. — Lavoisier,  in  1777,  first  demonstrated  that  the  two 
acids  of  phosphorus,  obtained  by  the  slow  and  by  the  rapid  com- 
bustion, are  different  compounds,  owing  to  their  different  propor- 
tions of  oxygen. 

2.  PREPARATION. 

(a.)  Till  Sir  H.  Davy  proved  the  contrary,  it  was  thought  that  the 
only  mode  of  preparing  phosphorous  acid,  was  by  a  slow  combustion 
in  the  air.  At  a  high  temperature,  phosphorus,  whether  burning  in 
common  air  or  in  oxygen  gas,  is  saturated  with  oxygen,  and  produ- 
ces phosphoric  acid ;  at  a  common  temperature  it  becomes,  at  least 
in  part,  phosphorous  acid. 

*  Fourcroy,  II.  69.         t  Corresponding,  if  phosphorus  is  12,  with  5  equiv.  of  each. 

t  For  the  grounds  of  this  conclusion  see  Henry,  Vol.  I,  p.  377,  10th  ed.  This 
number  is  not  universally  adopted.  See  Turner's  Chemistry,  2d  ed.  p.  261,  where  it 
is  stated  that  M.  Dulong  conceives  the  oxygen  in  the  phosphorous  and  phosphoric 
acids  to  be  in  the  proportion  of  1.5  to  2.5  or  3 : 5,  and  Berzelius  thinks  that  phospho- 
ric acid  is  composed  of  oxygen  56  parts  and  phosphorus  44,  (very  near  the  results 
obtained  by  Lavoisier.) 

54 


426  PHOSPHOROUS  ACIDS. 

(b.)  Place  slicks  of  phosphorus  in  a  glass  funnel,  standing  in  the 
mouth  of  a  bottle ;  a  heavy  acid  vapor  falls  in  a  white  current,  and 
becomes  liquid  by  deliquescence.* 

The  phosphorus  is  increased  in  weight,  by  that  of  the  oxygen  and 
water  imbibed,  and  1  part  thus  produces  3  or  4  of  phosphorous  acid. 
It  is  found,  kowever,  that  the  product  is  not,  as  was  formerly  suppo- 
sed, phosphorous  acid  alone. 

Sir  H.  Davy  found  it  to  be  a  mixture  of  phosphorous  and  phos- 
phoric acids ;  but  it  is  suggested  by  Murray  that  it  is,  when  first  form- 
ed, wholly  phosphoric  acid,  but  that  in  condensing  it  unites  with  more 
oxygen  and  becomes,  in  part,  phosphoric  acid.  It  appears  probable 
that  there  is  a  definite  compound  of  phosphorus  and  oxygen,  forming 
phosphorous  acid,  although  as  obtained  by  deliquescence,  the  two 
acids  are  present  in  mixture. 

3.  PROPERTIES  of  this  mixed  acid.\ 

(a.)  A  transparent  dense  fluid,  viscid,  adhering  to  the  glass  like 
oil,  but  possessing  various  degrees  of  density  as  it  has  imbibed  more 
or  less  water. 

(b.)  It  reddens  dark  vegetable  colors,  and  sets  the  teeth  on  edge. 

(c.)  When  heated,  a  part  of  the  water  is  evaporated,  and  it  emits 
a  white  dense  smoke,  of  an  alliaceous  odor,  which  in  the  open  air, 
takes  fire  with  a  vivid  flash ;  and  the  substance  becomes  entirely 
phosphoric  acid. 

Sd.)  This  acid  combines  with  water  in  every  proportion. 
e.)  Aided  by  heat,  nitric  acid  readily  converts  this  acid  into  phos- 
phoric acid ;  proportions,  1  of  the  phosphorous  acid,  to  8  of  the  ni- 
trous, of  the  sp.   gr.   1.3.     This  is  perhaps  the  best  process  for  ob- 
taining pure  phosphoric  acid. 

USES  IN  MEDICINE,  &c. — Valuable  as  a  remedy  against  uterine 
hoemorrhage,  in  parturition.  J  Probably  it  would  act  also  as  a  tonic. 

OTHER  MODES  OF  COMBINING  PHOSPHORUS  WITH  OXYGEN. 

(a.)  Every  person  conversant  with  phosphorus  must  have  observ- 
ed that  when  it  is  kept  immersed  in  water,  the  air  not  being  entirely 
excluded,  it  is  slowly  oxygenized ;  and  the  water  becomes  acid. 


*  This  simple  arrangement  is  sufficient,  but  Fourcroy  recommends  to  place  the 
phosphorus  in  glass  tubes,  wide  open  at  top,  and  capillary  at  the  bottom  ;  their  points 
converge  in  the  throat  of  a  large  glass  funnel ;  they  are  thus  secured  from  taking 
fire;  the  funnel  is  placed  in  a  bottle,  the  bottle  on  a  plate  having  water  in  it,  and 
over  the  whole  stands  a  glass  receiver,  with  two  apertures  at  its  sides,  to  regulate 
the  admission  of  the  air ;  the  bottom  of  the  receiver  is  immersed  in  the  water.  This 
.arrangement  I  have  tried ;  it  is  neat  and  effectual,  but  more  complex  than  is  necessary. 

t  Dulong  calls  the  acid  thus  obtained  the  phosphatic,  regarding  it  as  a  distinct 
compound,  (Phil.  Mag.  XLVIII,  273,)  but  this  opinion  is  not  generally  adopted. 

t  Used  by  the  late  eminent  Dr.  Eneas  Munson,  of  New  Haven,  who  practised 
medicine  with  great  success  for  60  years.  I  used  to  supply  him  with  this  acid,  and 
his  language  was,  that  it  operated  in  such  cases,  like  a  charm. 


PHOSPHOROUS  ACID3.  427 

(b.)  The  sticks  of  phosphorus  are  also  covered  witli  a  white  in- 
crustation, which  was  formerly  supposed  to  be  an  oxide  of  phos- 
phorus. 

(c.)  If  the  phosphorus  be  at  the  same  time  exposed  to  the  light, 
the  incrustation  becomes  brown,  water  being  decomposed,  as  is 
evinced  by  the  evolution  of  phosphuretted  hydrogen,  and  the  forma- 
tion of  the  phosphorus  and  phosphoric  acids.* 

(d.)  When  phosphorus  is  burned  in  less  atmospheric  air  than  is 
necessary  to  its  entire  consumption,  there  remains  a  red  substance, 
supposed  by  some  to  be  a  hyd rated  oxide,  but  the  exact  composition 
of  the  oxides  of  phosphorus  has  not  yet  been  ascertained.  I  have 
observed  that  the  same  substance  is  formed  when  phosphorus  is  burn- 
ed in  oxygen  gas. 

(e.)  Phosphorus  being  burned  in  highly  rarefied  air,  produces  a 
"  red  solid,  comparatively  fixed,  and  requiring  a  heat  above  212° 
for  its  fusion — a  white,  and  easily  volatile  substance,  which  is  com- 
bustible, soluble  in  water,  and  has  acid  properties,  and  a  substance, 
which  is  strongly  acid,  and  not  volatile,  even  at  a  white  heat.f  The 
first  appears  to  be  a  mixture  of  unburned  phosphorus,  and  phospho- 
rous acid  ;  the  second  to  be  phosphorous  acid ;  and  the  third  to  be 
phosphoric  acid."J 

The  white  volatile  solid  unites  with  bases,  and  forms  salts,  that 
are  called  phosphites.  This  acid  absorbs  oxygen  from  the  air,  and 
becomes  phosphoric  acid,  and  on  account  of  its  avidity  for  oxygen, 
it  precipitates  the  salts  of  mercury,  silver,  platinum  and  gold. 

PHOSPHOROUS  ACID  OF  DAVY. 

REMARK. — According  to  Sir  H.  Davy,  as  already  stated,  what  has 
been  usually  called  phosphorous  acid,  is  a  mixture  of  the  phosphorous 
and  phosphoric. 

1.  PREPARATION. 

(a.)  Sublime  phosphorus  through  corrosive  sublimate,  and  a  limpid 
fluid  is  obtained,  a  compound,  as  is  supposed  of  chlorine  and  phos- 
phorus. 

(6.)  Mix  this  product  with  water,  and  apply  heat  till  the  liquid  is 
of  the  consistence  of  syrup  ;  it  is  said  to  be  a  solution  of  pure  phos- 
phorous acid  in  water,  and  it  becomes  solid  and  crystalline  on  cool- 


*  I  have  a  bottle  of  sticks  of  phosphorus  which  were  put  up  for  me  in  London,  25 
years  ago.  Having  been  distilled  in  hydrogen  gas,  they  were  then  white,  but  they 
are  now  covered  by  a  lively  red  crust,  and  the  water,  which  has  never  been  chang- 
ed, is  decidedly  acid. 

t  According  to  the  views  now  entertained  of  the  pure  glacial  phosphoric  acid,  it 
should  be  volatilized  at  a  lower  heat  than  that  stated  in  the  text,  on  the  authority  of 
Sir  H.  Davy. 

t  Henry,  10th  Ed.  Vol.  I,  p.  371. 


428  PHOSPHOROUS  ACIDS. 

ing.     The  theory  will  be  intelligible  after  chlorine  has  been  dis- 
cussed. 

2.  PROPERTIES. 

(«.)  Jlcid  to  the  taste — reddens  vegetable  blues,  and  forms  phos- 
phites with  alkalies. 

(6.)  Odor  fetid — give  white  vapors  by  heat — combustible  in  the 
air,  and  therefore  contains  an  excess  of  phosphorus,  which  being  ex- 
pelled or  burned,  the  residuum  is  phosphoric  acid. 

3.  COMPOSITION. 

Phosphorus,  56.81          100          132 

Oxygen,  -     43.19  76          100 


100.00* 

Phosphorus,  56.524         100 

Oxygen,  -     43.476  76.92 

lOO.f 

By  a  more  recent  investigation,  Sir  H.  Davy  concluded  that 
phosphorous  acid  contains  just  half  as  much  oxygen  as  phosphoric 
acid.  Phosphorus,  59.7  100. 

Oxygen,  -     40.3  67.5 

100. 

4.  CONSTITUTION. — Taking  it  for  granted,  that  in  phosphorous 
acid,  the  elements  are  united,  equivalent  and  equivalent,  and  calling 
phosphorus  12  ;  the  phosphorous  acid  will  be  represented  by  12  +  8 
=20,  the  representative  number,  J  while  phosphoric  acid  is  supposed 
to  be  composed  of  phosphorus,  1  equivalent,  12,  and  oxygen,  2 
equivalents,  16=28,  as  stated  under  phosphoric  acid. 

The  above  are  the  views  of  Sir  H.  Davy  and  Dr.  Thomson,  but 
Berzelius  and  Dulong  consider  the  oxygen  in  the  two  acids  as  being 
in  the  proportion  of  2  to  5. 


HYPO-PHOSPHOROUS  ACID. 


1.  HISTORY. — Discovered  by  Mr.  Dulong^  in  consequence  of 
observing  the  peculiar  action  of  phosphuret  of  baryta  upon  water. 

2.  PREPARATION. 

(a.)  By  this  action,  two  compounds  are  said  to  be  formed;  an  in- 
soluble phosphate  of  the  earth  easily  separable  by  the  filter. 
(b.)  Jl  soluble  barytic  salt  which  passes  through  the  filter. 


*  Gay-Lussac.  t  Dulong,  Phil.  Mag.  XLVIII,  273. 

t  Henry,  Vol.  I,  p.  373,  10th  Ed.  §  Phil.  Mag-.  V.  48,  p.  271. 


PHOSPHATES.  429 

(c.)  Decompose  the  latter  by  just  so  much  sulphuric  acid,  as  pre- 
cipitates the  earth. 

(d.)  An  acid  solution  remains,  which,  after  evaporation,  is  viscous, 
tenacious,  and  uncrystallizable. 

(e.)  By  a  stronger  heat,  phosphuretted  hydrogen  gas  is  expelled — 
phosphorus  sublimed  and  phosphoric  acid  remains. 

3.  PROPERTIES. 

(a.)  Forms  with  alkaline  and  earthy  bases,  salts  of  extreme  solu- 
bility. 

(b.)  Those  of  baryta  and  strontia,  crystallize  with  great  diffi- 
culty. 

(c.)  Those  of  the  alkalies  are  soluble  in  all  proportions,  in  highly 
rectified  alcohol. 

(d.)  That  of  potassa  is  more  deliquescent  than  muriate  of  lime. 

(e.)  Absorb  oxygen  slowly  from  the  air,  and  by  heat  applied  in  a 
retort,  give  the  same  products  as  the  acid  itself. 

4.  COMPOSITION. — Phosphorus,  72.75          100. 

Oxygen,        27.25  37.44 

100. 

Calculated  by  Dulong,  upon  the  supposition  that  it  is  a  binary 
compound  of  oxygen  and  phosphorus,  but  it  may  be  a  triple  com- 
pound of  these  two,  and  hydrogen  forming  an  hydracid ;  in  which 
case,  its  proper  name  would  be  hydro-phosphorous  acid.  Sir  H. 
Davy  thinks  that  the  oxygen  of  this  acid  is  just  half  that  of  phospho- 
rous acid,  and  of  course  that  100  of  phosphorus  are  combined  with 
33.75  oxygen.  If,  as  above  stated,  phosphorous  acid  consists  of  an 
equivalent  of  each  element,  it  is  probable  that  this  acid  contains  two 
equivalents  of  phosphorus,  12  x2=24-f- 1  of  oxygen,  8=32,  its  rep- 
resentative number.*  It  is  not  certain  that  we  are  yet  accurately 
acquainted  with  the  proportions  of  the  elements  in  the  acids  of  phos- 
phorus. 

PHOSPHATES. 

General  Characters. 

(a.)  Phosphates  of  alkalies  partially  decomposed  by  ignition  with 
charcoal ;  phosphate  of  ammonia  is  decomposed  by  heat  alone. 

(b.)  Phosphates  of  the  alkaline  earths  not  decomposed  when  heat- 
ed with  charcoal,  nor  is  phosphorus  obtained. 

(c.)  Before  the  blowpipe,  both  alkaline  and  earthy  phosphates, 
melt  into  a  vitreous  globule,  sometimes  transparent  and  sometimes 
opake ;  that  of  ammonia  is  dissipated  entirely. 


*  Henry,  Vol.  I,  p.  374,  10th  Ed. 


430  PHOSPHATES. 

(d.)  Soluble  in  nitric  and  phosphoric  acid,  without  effervescence, 
and  precipitated  from  that  solution  by  lime  water  or  ammonia. 

(e.)  Sulphuric  acid  decomposes  them,  at  least  in  part,  and  sepa- 
rates the  phosphoric  acid. 

(/.)  Often  phosphoresce  by  heat. 

Form  bi-phosphates  and  some  triple  salts. 

Those  of  the  alkalies,  soluble ;  of  the  earths,  insoluble. 

PHOSPHATE  OF  POTASSA. 

1.  PREPARATION. 

Sa.)  In  the  mode  soon  to  be  mentioned  for  the  phosphate  of  soda. 
b.)  By  heating  the  bi-phosphate  in  a  platinum  crucible,  along  with 
pure  potassa. 

2.  PROPERTIES. 

(a.)  Insoluble  in  cold,  but  soluble  in  hot  water ;  "  it  precipitates 
as  the  solution  cools  in  a  brilliant  gritty  powder."  Very  fusible — 
producing  before  the  blowpipe  a  transparent  bead — opake  on  cooling, 
Forms  a  "  thick,  glutinous  and  adhesive"  solution  in  muriatic,  nitric, 
and  phosphoric  acids ;  alkalies  occasion  no  precipitate  from  these 
solutions,  if  much  diluted ;  otherwise,  the  reverse. 

The  vegetable  grains  belonging  to  the  Cerealia,  contain  a  small 
quantity  of  this  salt. 

It  is  supposed  to  be  a  compound  of  1  equivalent  of  water,  2  of 
acid,  and  1  of  alkali. 

It  is  said  that  a  subphosphate  of  potassa  is  obtained  by  fusing  po- 
tassa and  phosphate  of  potassa  together,  in  a  platinum  crucible. 

It  is  insoluble  in  cold,  but  sparingly  soluble  in  hot  water.  It  is 
supposed  that  it  has  two  equivalents  of  potassa  and  1  of  acid,  while 
the  neutral  phosphate  contains  one  equivalent  of  each  constituent,  and 
the  bi-phosphate,  2  of  acid  to  1  of  alkali. 

Bl-PHOSPHATE  OF  POTASSA. 

1.  PREPARATION. — Formed  by  dropping  liquid  phosphoric  acid 
into  carbonate  of  potassa,  till  effervescence  ceases,   and  the  liquid 
ceases  to  precipitate  muriate  of  baryta. 

2.  PROPERTIES. 

(a.)  By  evaporation  crystallizes  in  square  prisms ;  the  primary 
form,  an  octahedron  with  square  bases.  The  composition  is,  1 
equivalent  of  potassa,  2  of  phosphoric  acid,  and  2  of  water. 

(b.)  Very  soluble  in  water;  taste  bitter;  sp.  gr.  2.8516;  by 
heat,  melts  and  loses  its  water  ;  becomes  dry,  and  again  deliquesces. 
At  ignition,  melts  into  a  transparent  deliquescent  glass.  Exists  in 
small  quantities  in  barley.* 

*  Hope.     Note  Book. 


PHOSPHATES.  431 


PHOSPHATE  OF  SODA. 

Dr.  Pearson,  of  London,  introduced  it  into  medicine,  and  his 
process  for  forming  it,  is  as  follows — 

1.  PREPARATION. 

(a.)  To  a  solution  of  1400  grs.  crystallized  carbonate  of  soda,  at 
150°,  in  2.100  grs.  of  water;  add  by  degrees,  500  grs.  phosphoric 
acid  of  the  sp.  gr.  1.85  ;  boil,  filter  while  hot,  and  crystals  will  con- 
tinue to  form  for  several  days.  From  the  above  quantity  of  materi- 
als, Dr.  Pearson  obtained  from  1450  to  1550  grs.  of  crystals. 

(b.)  The  usual  process  is  to  add  carbonate  of  soda  in  excess,  to 
the  impure  phosphoric  acid,*  procured  from  the  decomposition  of 
bone  ashes  by  sulphuric  acid.  (See  phosphate  of  lime.)  The  solution 
is  filtered,  and  crystals  are  obtained  by  slow  evaporation. f 

2.  PROPERTIES. 

(a.)  The  phosphate  of  soda  of  the  shops  has  an  excess  of  alkali, 
which  is  said  to  be  essential  to  the  formation  of  good  crystals  ;  they 
are  rhomboidal  prisms,  with  pyramidal  terminations,  and  their  solution 
turns  blue  vegetable  colors  green. 

(b.)  Its  taste  is  much  like  that  of  common  salt. 

(c.)  From  this  circumstance,  it  is  advantageously  employed  as  a 
purgative,  as  it  may  be  taken  in  broth,  &c.  without  disgust,  and  even 
without  the  patient's  knowledge.  Dose,  from  six  drachms  to  one 
ounce. 

(d.)  Soluble  in  about  4  parts  of  water,  at  60°,  and  in  2,  at  212. 

(e.)  Suffers  the  aqueous  fusion,  and  loses  .62  of  water,  dries,  and 
melts  at  a  red  heat ;  by  cooling  after  blowpipe  fusion,  assumes  a  poly- 
hedral form. 

(f.)  Effloresces  rapidly  on  the  surface. 

(g.)  The  strong  acids  decompose  it  partially,  and  the  free  phos- 
phoric acid  forms  a  very  soluble  bi-phosphate. 

(h.)  With  most  of  the  earths,  fuses  into  vitreous  compounds,  be- 
ing an  excellent  flux. 

(i.)  In  the  humid  way,  baryta,  strontia,  and  lime,  attract  its  acid  j 
it  is  doubtful  whether  potassa  decomposes  it. 

3.  COMPOSITION — of  the  dry  salt. 

Phosphoric  acid,  53.48         100 

Soda,  -     46.52 

100.00J: 


*  Holding  phosphate  of  lime  in  solution,  which  is  precipitated. 
t  For  processes,  vide  Black's  Lectures,  Vol.  II,  233  and  4. 
t  Bevzelius,  Ann.  de  Chim.  et  de  Phys.  II,  164. 


432  PHOSPHATES. 

Dry  phosphoric  acid,  1  equivalent,      28  or  46.67 
Soda,  1          "  32  or  53.33 

Its  equivalent,   60  100.00 

In  crystals  ;  Phos.  acid,  1  equivalent,        28*  16.39 

Soda,            1           "               32  18.73 

Water,       12           "             108  64.88 

Its  equivalent,  168     lOO.OOf 

According  to  Mr.  Dalton's  opinion,  the  salt  above  described  is  a 
bi-phosphate,  having  2  atoms  of  acid,  and  1  of  base,  with  double 
the  acid,  making  a  quadro-phosphate — it  is  neutral  as  to  test  colors.  > 

To  render  the  common  or  bi-phosphate  neutral,  Mr.  Dalton  says 
that  its  sodaf  must  be  doubled,  when  it  will  acquire  much  more  sol- 
ubility, and  crystallize  in  fine  needles. 

Mr.  Dalton  recommends  this  form  of  the  salt  as  a  test.  Dr.  Hen- 
ry remarks,  that  fresh  experiments  are  necessary  to  reconcile  these 
discordant  statements.^ 

By  heat  on  a  sand  bath,  the  crystals  loose  12  equivalents  of  water, 
without  changing  their  properties.  It  is  said  that  they  still  retain 
£  an  equivalent  of  water,  which  they  give  up  at  ignition ;  and  then 
being  redissolved  in  water,  and  the  solution  spontaneously  evap- 
orated, irregular  four  sided  prisms  are  obtained,  whose  primary  is  a 
rhombic  octahedron ;  they  do  not  effloresce,  are  much  less  soluble 
than  before,  and  consist  of  1  equivalent  of  acid,  and  1  of  soda, 
with  5  of  water.  The  solution  precipitates  nitrate  of  silver,  white, 
and  not  yellow,  like  the  common  phosphate.  A  phosphate  of  soda 
has  also  been  obtained,  from  a  solution  evaporated  at  90°,  con- 
taining 7  J  equivalent  of  water ;  they  are  permanent  in  the  air,  and 
have  a  different  form  from  the  common  phosphate.  || 

4.  MISCELLANEOUS. 

(a.)  Exists  in  human  urine,  with  phosphate  of  ammonia  and,  the 
concrete  salts,  obtained  by  evaporation,  are  principally  these  two ; 
formerly,  under  the  name  of  microcosmic  salt,  much  employed  as  a 
flux,  with  the  blowpipe. 

(b.)  The  phosphate  of  soda  is  used  for  the  same  purpose,  and  be- 
sides its  use  in  medicine,  it  is  advantageously  employed  as  a  substi- 
tute for  borax  in  the  soldering  of  metals. 

(c.)  It  is  useful  in  chemistry ;  by  double  exchange,  we  can  thus 
form  almost  all  other  phosphates. 


*  35.71,  Mitscherlich,  quoted  by  Turner,  2d  Ed.  p.  581. 

t  Thomson's,  First  Prin.  I,  201. 

t  By  adding  as  much  again  caustic  soda.  §  Turner,  Vol.  I,  p.  568. 

{I  Turner,  2d  Edition,  p  281,  and  Edin.  Jour.  XIV,  No.  p.  298. 


PHOSPHATES.  433 

PHOSPHATE  OF  AMMONIA. 

1.  PREPARATION. 

(a.)  By  saturating  pure  phosphoric  acid  with  ammonia. 

(b.)  By  decomposing,  by  carbonate  of  ammonia,  the  acidulous 
liquor  proceeding  from  the  action  of  sulphuric  acid  upon  bone  ashes. 
(See  phosphate  of  lime.) 

2.  PROPERTIES. 

(a.)  Its  crystals  are  rhombic  prisms,  terminated  by  dihedral  sum- 
mits ;  the  primary  form  is  an  oblique  rhombic  prism,  whose  smaller 
lateral  angle  is  84°,  30' ;  sometimes  it  is  obtained  in  needles. 

(b.)  Its  taste  is  sharp,  cooling,  and  ammoniacal. 

re.)  Sp.  gr.  1.8051. 

(d.)  Soluble  in  4  parts  of  water  at  60°,  and  in  less  at  212°; 
crystallizes  on  cooling,  but  not  beautifully,  unless  by  spontaneous 
evaporation. 

(e.)  Not  affected  by  the  air. 

(/.)  Suffers  the  aqueous  fusion,  and  is  decomposed  by  heat;  the 
ammonia  is  exhaled,  and  the  phosphoric  acid  melts  into  a  vitreous 
globule. 

(g.)  This  is  one  mode  by  which  the  phosphoric  acid  is  obtained 
pure,  or  nearly  so. 

(h.)  On  account  of  the  facility  with  which  this  salt  is  decomposed 
by  heat,  it  affords  phosphorus  when  heated  with  charcoal. 

3.  COMPOSITION. — Acid  28 -{-17  ammonia,  or  62.22,  and  37.78. 
There  is  said  to  be  also  Ij  equivalent  of  water.* 

4.  MISCELLANEOUS. 

(a.)  It  exists  in  urine,  mixed  with  the  phosphate  and  muriate  of 
soda,  from  which  it  is  difficult  to  free  it ;  in  that  state  it  forms  the 
long  famed  microcosmic  salt. 

.  (b.)  In  its  pure  state  not  employed;  but  the  microcosmic  salt  has 
been  much  used  as  a  flux  for  the  mineralogist,  and  in  the  composi- 
tion of  the  pastes. 

BI-PHOSPHATE    OF    AMMONIA. 

1 .  PREPARATION. — By  adding  to  phosphoric  acid,  ammonia  or  its 
carbonate,  till  the  solution  ceases  to  precipitate  muriate  of  baryta. 

2.  PROPERTIES. — Less  soluble  than  the  natural  phosphate  ;  no 
change  in  the  air ;  primary  form,  an  octahedron,  with  a  square  base, 
but  the  right  square  prism,  with  a  rhombic  base  is  most  frequent.f 

3.  COMPOSITION. — Acid,  2  equivalents,  56+2  of  ammonia,  34 
+  3  of  water,  27=117  for  its  equivalent. 


*  Turner,  quoting  Mistcherlich. 
t  Turner. 


55 


434  PHOSPHATES. 

PHOSPHATE    OF    SODA    AND    AMMONIA. 

1.  PREPARATION. — By   dissolving    in  a  little  boiling   water,   1 
equivalent  of  muriate  of  ammonia,  and  1  of  phosphate  of  soda  ;  the 
double  phosphate  crystallizes  as  the  fluid  cools,  and  muriate  of  soda 
remains  in  solution. 

2.  PROPERTIES. 

(a.)  Primary  form,  the  oblique  rhombic  prism  ;  effloresces,  losing 
ammonia,  and  passes  to  the  condition  of  bi-phosphate  of  soda. 

(6.)  Decomposed  by  heat ;  the  ammonia  and  water  are  dissipated 
and  a  very  fusible  bi-phosphate  of  soda  remains. 

3.  COMPOSITION. — 1    equivalent   phosphate    of  soda,  60, -{-1   of 
phosphate  of  ammonia  45,-f  10*  of  water  in  the  crystals =90  =  195. 

Remarks. — This  is  the  microcosmic  salt,  in  a  state  of  purity. 
According  to  Fourcroy,  this  salt  effloresces,  loses  its  ammonia,  and 
passes  to  the  condition  of  bi-phosphate  of  soda.  It  turns  tincture  of 
violets  green.  The  ammonia  is  said  to  be  dissipated  by  repeated  so- 
lutions and  crystallizations. 

PHOSPHATE    OF    LIME. 

1.  DISCOVERY. — By  Gahn  and  Scheele,  in  1774,  who  found  that 
hones  consist  principally  of  this  substance,  with  some  other  salts, 
cemented  by  gelatine  ;  it  exists  in  bones,  in  the  proportion  of  86  per 
cent. 

2.  PREPARATION. 

(a.)  By  precipitating  lime  water,  by  liquid  phosphoric  acid— 
(b.)  Or,  phosphorus  burned  beneath  a  bell  glass  inverted  over 
lime  water,  becomes  phosphoric  acid,  and  precipitates  the  lime — 

!c.)  Or,  by  mingling  solutions  of  phosphate  of  soda,  and  muriate 
ime,  adding  the  muriate  lastf — 

(df.)  Or,  we  may  purify  the  phosphate  of  lime  of  bones — or.  lix- 
iviate bone  ashes  with  abundance  of  hot  water,  to  remove  muriate 
and  phosphate  of  soda,  and  the  carbonate  of  lime  may  be  dissolved  by 
acetic  acid ;  or,  dissolve  the  phosphate  by  muriatic  acid  and  precipi- 
tate by  ammonia ;  the  phosphate  falls  without  decomposition,  and 
after  being  dried  is  pure.  J 

3.  PROPERTIES. 

(a.}  A  white  powder,  never  crystallized  except  as  a  native  mineral, 
(b.)  Insoluble  in  water,  tasteless  and  inodorous. 
(c.)  Melts  by  the  most  intense  heat  into  an  opake  white  enamel, 
(d.)  Unaffected  by  the  air. 

(e.)  Formed  with  water,  into  a  paste,  it  is  made  into  cupels  for 
ithe  assay ers. 

*  Mistcherlich  quoted  by  Turner. 

1  Otherwise  the  .precipitate  will  have  excess  of  base,  and  the  liquor  will  be  acid. 
— Berzelius.  +  Fourcroy. 


PHOSPHATES.  435 

(/*.)  Partially  decomposed  by  acids,  especially  the  stronger,  and 
even  by  the  vegetable  acids. 

4.  COMPOSITION. — One  equivalent  of  acid,  28,  and  one  of  lime,  28. 
BI-PHOSPHATE  OF  LIME   is  easily  formed  by  dissolving  phosphate 

of  lime  in  as  much  phosphoric  acid  as  the  salt  contains,  and  it  is  always 
formed,  (or  at  least  a  phosphate  with  excess  of  acid,)  in  the  decom- 
position of  bone  ashes,  as  will  appear  more  particularly  farther  on. 
The  bi-phosphate  is  very  soluble  in  water  and  does  not  crystallize.* 
It  melts  before  the  blowpipe  into  a  transparent  globule  ;  it  is  insoluble, 
and  doubtless,  by  the  heat,  loses  the  excess  of  acid. 

Remark. — For  a  notice  of  Mr.  Dalton's  views  respecting  the  bi- 
tri-  quadri-  octo-  and  dodeca-phosphate  of  lime,  containing,  as  is  sup- 
posed, 2,  3,  4,  8  and  12  equivalents  of  acid,  reference  may  be  had 
to  Henry's  Chemistry,  10th  ed.  Vol.  I,  p.  591. 

5.  MINERAL  AND  ANIMAL  PHOSPHATE. 

Found  as  a  mineral  in  many  countries  ;  in  Estremadura,  in  Spain, 
forms  extensive  rocky  strata  ;  it  is  there  used  in  building.  Most  of 
the  natural  phosphates  are  highly  phosphorescent  by  heat ;  animal 
phosphates  are  not.  Occurs  crystallized  in  Saxony,  Bohemia,  Eng- 
land, United  States,  &c.  in  six  sided  prisms  and  tables  ;  it  is  called 
apatite  and  asparagus  stone. 

It  exists  in  most  animal  fluids;  in  human  urine,  in  the  form  of 
bi-phosphate,  and  is  precipitated  by  lime  water  and  the  alkalies ;  in 
milk  and  blood  ;  it  is  found  in  the  muscles  and  in  jelly ;  in  preter- 
natural ossifications,  and  in  most  of  the  calculi,  whether  in  the  kid- 
neys or  the  bladder.  It  exudes  through  the  skin,  and  is  found  in 
the  solid  excrements  of  animals  whose  urine  does  not  contain  it.  It 
is  found  also  in  the  ashes  of  both  vegetable  and  animal  substances. 

6.  PROCESS  FOR  PHOSPHORUS. f 

(a.)  Burn  bones  in  a  furnace,  or  even  in  a  common  fire;  the  oils, 
gelatine,  &ic.  will  be  consumed  and  the  osseous  part  will  be  easily 
pulverized.  In  an  earthen  pan  or  dish,  place  bone  ashes  2  parts, 
water  20  and  sulphuric  acid  1  ;J  digest  them  upon  embers  or  by  a 
sand  heat,  and  stir  thoroughly,  with  a  glass  rod  during  ten  or  twelve 
hours  ;  throw  the  mass  upon  a  coarse  linen  filter,  stretched  over  a 
frame  with  tenter  hooks;  wash  the  insoluble  residuum  with  boiling 
water  till  it  comes  orT  tasteless ;  the  fluid  will  be  turbid ;  let  it 
settle,  and  then  draw  it  off  clear ;  evaporate  in  a  clean  copper  or  tin 
vessel  to  dryness  ;  or,  it  will  answer  if  still  moist. 


*  Fourcroy  says  it  can  be  made  to  crystallize  in  brilliant  micaceous  scales. 

t  For  a  series  of  years,  I  was  in  the  habit  of  manufacturing  all  the  phosphorus 
required  in  the  experiments  of  the  laboratory,  and  nearly  every  part  of  the  annexed 
statement  I  have  repeatedly  verified  by  my  own  experience. 

t  There  will  be  a  considerable  effervescence  owing  to  carbonate  of  lime,  and  as 
is  said,  carbonate  of  soda. 


436  PHOSPHATES. 

(6.)  The  fluid  obtained  by  the  filtration  is  acidulous  phosphate  and 
acidulous  sulphate  of  lime;*  the  two  neutral  salts  being  held  in  solu- 
tion by  an  additional  quantity,  probably  an  equivalent  of  their  respec- 
tive acids.  To  free  the  fluid  from  the  earthy  matter  thus  dissolved, 
the  liquor  may  be  decomposed  by  acetate  or  nitrate  of  lead,  and  the 
precipitate  of  phosphate  of  lead  may  be  decomposed  by  heating  it 
in  an  earthen  retort,  with  half  its  weight  of  charcoal  powder.  The 
phosphorus,  obtained  in  this  way,  may  be  contaminated  with  sulphur, 
because  sulphate  of  lead  is  thrown  down  by  the  acetate  or  nitrate  ; 
this  may  be  got  rid  of,  by  decomposing  the  phosphate  of  lead  by  sul- 
phuric acid,  and  then  the  liberated  phosphoric  acid  by  charcoal. 

(c.)  This  process  is  complicated,  and  it  is  better  to  decompose  the 
.acidulous  phosphate  by  adding  carbonate  of  ammonia;  the  phosphate 
of  ammonia,  on  being  evaporated  and  heated  to  low  redness,  gives 
up  its  ammonia ;  sulphate  of  ammonia,  if  present,  is  volatilized,  and 
the  phosphoric  acid  is  obtained  nearly  or  quite  pure.  But  even  this 
is  unnecessary,  if  the  object  is  merely  to  obtain  the  phosphorus ;  for 
that  purpose  the  acidulous  phosphate  may  be  at  once  decomposed. 

(d.)  The  purified  acid,  mixed  ivith  one  half  its  weight  of  charcoal 
powder  and  heated  in  a  furnace,  affords  about  one  fourth  of  its  iveight 
of  phosphorus.^ 

(e.)  The  solid  residuum  from  (b)  is  commonly  employed  to  afford 
phosphorus. 

(/.)  It  is  mixed  with  from  J  to  J  its  weight  of  dry  powdered  char- 
coal and  distilled. 

(g.)  The  acidulous  solution,  when  considerably  evaporated,  must 
be  suffered  to  cool,  and  sulphate  of  lime  will  subside,  which  must  be 
separated. 

(A.)  The  earthen  retort  is  glased  with  lime,  1  part,  slacked  ivith  a 
solution  of  2  parts  of  borax;  and  with  this  mixture  the  retort  is  wash- 
ed thoroughly,  inside  and  out ;  when  it  is  heated  it  will  melt  and  fill 
the  pores  through  which  the  phosphorus  would  otherwise  escape. 

(i.)  The  retort  is  carefully  coated  with  fire  lute,  and  its  neck  dips 
into  water  ;  the  heat  is  very  gradually  raised,  and  much  gas  is  pro- 
duced ;  it  burns  spontaneously,  with  brilliant  flashes  ;  we  continue 
the  heat  some  time  after  gas  has  ceased  to  come. 

(/.)  If  the  neck  of  the  retort  is  choked,  which  is  ascertained  by  a 
wire,  a  hot  iron  bar  is  applied  to  it  externally  to  melt  the  phosphorus. 

(/c.)  Some  phosphorus  may  come  over  into  the  water,  but  most 
of  it  condenses  in  the  neck  of  the  retort,  and  must  be  got  out  by 
heating  it  with  water  poured  from  a  tea  kettle. 

*  Perhaps  bi-phosphate  and  bi-sulphate. 

t  It  is  said  not  to  be  so  good  for  (his  purpose  as  the  acidulous  phosphate,  because- 
it  is  more  liable  to  be  volatalized. 


PHOSPHATES'.  437 

(/.)  Phosphorus  is  purified  by  straining  it  through  leather  under 
hot  ivater;  or  better  by  distillation  in  vessels  filled  with  hydrogen  gas. 
It  is  melted  under  hot  water,  in  a  retort,  and  suffered  to  congeal ;  the 
retort  is  then  filled  with  hydrogen  gas,  its  mouth  plunged  into  warm 
water,  and  the  distillation  is  performed  by  a  sand  heat  or  even  by  a 
naked  fire  :  it  is  a  delicate  and  difficult  process ;  I  have  been  suc- 
cessful with  it,  but  have  had  the  retort  break  from  the  regurgitation 
of  the  water ;  in  such  a  case  there  is  a  violent  and  even  dangerous 
combustion. 

(m.)  It  is  cast  into  sticks  in  the  throat  of  a  funnel,  or  drawn  up 
into  tubes  by  suction ;  the  finger,  protected  by  leather,  is  slipped 
over  the  end  of  the  tube,  and  the  latter  is  then  placed  in  cold  water. 

(n.)  Phosphorus  may  be  obtained  by  precipitating  the  phosphoric 
acid  from  urine,  or  from  phosphate  of  soda,  by  nitrate  or  acetate  of 
lead;  we  distil  the  concrete  residuum  with  charcoal.  About  14  or 
18  parts  of  phosphorus  are  afforded  by  100  parts  of  phosphate  of 
lead  ;  less  heat  is  necessary  in  this  than  in  the  process  with  bones. 

(o.)  The  product  of  phosphorus  is  greatest  ivhen  the  materials  are 
dry  and  the  distillation  is  slow.  Pelletier  obtained  60  ounces  at  one 
operation,  from  the  acid  of  36  Ibs.  of  bones,  (576  ounces,)  decom- 
posed by  30  Ibs.  of  sulphuric  acid ;  at  another  time  he  procured  only 
half  this  quantity. 

(p.)  Phosphorus  is  purified  by  liquid  chlorine.  It  should  be  pre- 
viously granulated,  which  is  done  by  melting  it  beneath  water  and 
shaking  it  as  the  water  cools ;  then  by  shaking  it  in  solution  of  chlo- 
rine the  color  is  in  a  few  minutes  removed.* 

PHOSPHATE  OF  BARYTA. 

1.  PREPARATION. — The  muriate  or  nitrate  of  baryta,  mixed  with 
the  phosphate  of  soda  or  ammonia,  produces  a  precipitate  of  phos- 
phate of  baryta. 


*  By  estimates  made  thirty  years  ago,  the  acids  which  decompose  the  phosphate  of 
lime,  take  up  uo  more  than  _*_"_  of  the  lime  it  contains,  and  separate  from  it  less 
than  half  the  phosphoric  acid ;  "  100  parts,  treated  by  an  acid,  afford  only  .33  of 
acidulous  phosphate  of  lime,  containing  only  .17  of  disengaged  phosphoric  acid  out 
of  the  .41  of  this  acid  which  exists  in  the  100  parts  of  phosphate  of  lime ;  so  that 
by  the  distillation  of  this  substance  with  charcoal,  we  obtain  only  about  .05  of 
phosphorus,  instead  of  .16  which  exist  in  the  100  parts  of  the  bases  of  bones."  It 
would  seem,  however,  (o.)  that  Pelletier  obtained  double  this  quantity.  Neutral 
phosphate  of  lime  remains  in  the  retort  after  the  distillation  of  phosphorus  ;  its 
origin  is  obvious.  We  decompose  no  more  phosphoric  acid  than  what  goes  to  hold 
in  solution  the  phosphate  of  lime.  In  the  process  of  the  older  chemists,  the  solid 
extract  of  urine  was  distilled  to  obtain  phosphorus  ;  only  the  phosphoric  acid  of  the 
phosphate  of  ammonia  was  decomposed  by  the  combustible  matter  present,  and 
therefore  very  little  phosphorus  was  obtained ;  the  product  is  increased  by  the  ad- 
dition of  charcoal. 


438  PHOSPHATES. 

2.  PROPERTIES. — White,  insipid,  pulverulent,  insoluble  in  water, 
soluble  in  nitric  and  muriatic  acids  ;  applied  to  no  use. 

3.  ITS  COMPOSITION,  after  being  washed  and  dried,  is,  according 
to  Berzelius — 

Phosphoric  acid,  31.8         100. 

Baryta,          -  -     68.2         214.46 

100. 

Dr.  Henry  suggests  that  if  it  be  constituted  of  1  equivalent  of  acid 
and  1  of  base,  its  composition  will  be  expressed  by 

Phosphoric  acid,  28         26.62         100 

Baryta,  -         -         _     78         73.38         280 


Its  equivalent,   106        100.00 

Berzelius,  by  dissolving  baryta  in  phosphoric  acid,  and  evaporating 
the  solution,  obtained  acidulous  crystals,  which,  if  composed  of  2 
equivalents  of  acid,  =56,  and  1  of  base,  =78  =  1<343  and  would  be 
a  bi-phosphate.  From  a  solution  of  these  crystals,  alcohol  precipi- 
tates a  bulky  white  and  tasteless  substance,  which  appears  to  be  com- 
posed of  2  equivalents  of  base,  and  3  of  acid,  or  if  we  say  1  of  the 
former  and  l£  of  the  latter,  it  would  be  called  a  sesqui-phosphate.* 

PHOSPHATE  OF  STRONTIA. 

1.  FORMATION  AND  PROPERTIES.  —  Every  thing  in  the  last  article 
is  applicable  to  this,  except  that  it  is  soluble  in  phosphoric  acid,  gives 
a  purple  flame  with  charcoal  before  the  blowpipe,  is  totally  decom- 
posed only,  by  the  sulphuric  acid  and  partially  by  the  nitric  and  mu- 
riatic acids.     It  is  fusible  by  the  blowpipe,  into  a  white  enamel  ;  it 
is  soluble  in  2000  parts  of  water. 

2.  COMPOSITION.—  Acid,   36.565,  base,  63.435  =  100.00. 

Dr.  Henry  remarks,  that  "  if  a  true  binary  compound,  it  should 
consist  of  very  nearly  65  base,  -f-  35  acid  ;  and  that  there  is  a  bi- 
phosphate  consisting  of  2  atoms  of  acid,  1  atom  of  base,  and  2  of 
water." 

PHOSPHATE  OF  MAGNESIA. 

1.  PREPARATION. 

By  digesting  phosphoric  acid  on  magnesia  or  the  carbonate. 

By  mixing  equal  quantities  of  the  concentrated  solutions  of 
sulphate  of  magnesia  and  phosphate  of  soda  ;  in  a  few  hours,  crys- 
tals of  phosphate  of  magnesia  are  formed. 


. 

(a.) 
(6.) 


*  Henry,  Vol.  I,  p.  605.     See   Berzelius  on  two  sub-phosphates,  Ann.  of  Phi!. 
XV,  277. 


PHOSPHATES.  439 

2.  PROPERTIES. 

(a.)  They  are  compressed  prisms;  speedily  effloresce  and  re- 
quire 1 5  parts  of  cold  water  for  solution  ;  hot  water  dissolves  so  much 
that  crystals  form  as  the  solution  cools. 

(b.)  Lose  water  of  crystallization  by  heat;  melt  by  a  still  higher 
heat  into  a  glass. 

(c.)  Decomposed  entirely  by  sulphuric,  nitric,  and  muriatic  acids, 
and  by  fixed  alkalies  and  alkaline  earths.  Ammonia  forms  a  triple 
salt,  which  exists  in  urine. 

(d.)  Composed  of  acid,  1  equivalent,  20;  base  1,  28=48,  and 
when  crystallized,  water  7  =  63  =  111. —  Thomson. 

PHOSPHATE  OF  AMMONIA  AND  MAGNESIA. 

1 .  DISCOVERY. — Found  by  Fourcroy,  in  the  calculus  of  a  horse;  ex- 
ists in  the  bones  of  most  animals,  and  is  common  in  the  human  subject. 

2.  PREPARATION. 

(a.)  Formed  by  adding  phosphate  of  ammonia,  or  ammonia,  or  its 
carbonate  to  phosphate  of  magnesia;  or  carbonate  of  ammonia  and 
afterwards  phosphate  of  soda  to  solution  of  sulphate  of  magnesia, 
when  the  double  phosphate  subsides  in  the  form  of  minute  grains. 

(b.)  Magnesia  is  detected  when  in  solution  in  an  acid,  with  or 
without  other  earths,  in  the  following  manner. 

(c.)  Add  to  the  solution  bi-carbonate  of  ammonia,  (formed  by  ex- 
posing common  carbonate  to  the  air,  till  it  has  lost  its  smell ;)  the 
other  earths  will  be  precipitated,  but  not  the  magnesia. 

(d.)  Add  a  cold  saturated  solution  of  phosphate  of  soda  ;  a  white 
powder  precipitates  which  is  the  ammoniaco-magnesian  phosphate. 

(e.)  Ammoniacal  phosphate  of  magnesia  is  a  white  powder  which 
lines  the  cavities  of  some  calculi  in  the  form  of  crystals^  and  is  fre- 
quently deposited  in  crystals. 

(f.)  Tasteless,  insoluble  in  water,  soluble  in  acids,  even  in  the 
acetic,  and  is  precipitated  unchanged  when  the  acid  is  saturated  by 
ammonia  ;  decomposed  by  heat,  the  ammonia  and  water  flying  away,, 
and  leaving  the  phosphate  of  magnesia ;  composed  of  equal  weights 
of  phosphate  of  ammonia,  phosphate  of  magnesia,  and  water.* 

PHOSPHATE  OF  ALUMINA. 

Phosphoric  acid  combines  with  alumina,  to  saturation,  forms  a 
white  insipid  powder  which  melts  before  the  blowpipe  into  a  transpa- 
rent globule. 

•&  •&  *•  #  •&  •* 

The  phosphates  of  the  other  earths  are  comparatively  unimportant. 

*  Its  composition  is  said  to  be  otherwise  not  accurately  determined.  Stromeyer 
states  the  magnesia  at  .37. — Turner. 

But  Thomson  states  it  at  1  equiv.  phosphate  of  magnesia,  48,  1  equiv.  phosphate  of 
ammonia,  45,  4  of  water,  36  ;  its  equivalent  being  129,  the  salt  being  dried  without 
heat. 


440  PHOSPHURETTED  HYDROGEN. 

BINARY  COMPOUNDS  OF  PHOSPHORUS  WITH  VARIOUS  BASES. 
PHOSPHURETTED  HYDROGEN.* 

1.  PREPARATION. 

(a.)  Hydrogen  gas  may  be  partially  phosphuretted,  by  heating 
phosphorus  in  it  by  the  solar  rays. 

(b.)  The  better  mode  is  to  heat  a  strong  alkaline  solution,  (potash 
or  soda,)  with  phosphorus  ;  the  retort  may  be  previously  filled  with 
hydrogen  gas. 

(c.)  To  do  this  properly,  introduce  the  phosphorus  and  fill  the  retort 
with  hot  water — as  it  cools,  the  phosphorus  will  congeal,  and  adhere 
to  the  bottom,  so  that  it  will  not  fall  out ;  throw  in  the  hydrogen  gas 
by  means  of  a  bladder  and  tube,  or  by  a  tut>e  coming  from  an  air 
jar,  or  a  gazometer ;  keep  the  mouth  of  the  retort  down,  and  with 
the  finger  upon  it,  dip  it  into  the  alkaline  solution ;  now  expel  so 
much  gas,  by  warming  the  retort,  that  when  it  cools,  the  requisite 
portion  of  fluid  may  enter. 

(d.)  Or,  fill  the  retort  with  the  alkaline  solution,  and  throw  out  by 
hydrogen  gas,  as  much  as  you  choose. f 

(e.)  Or,  we  may  mix  lime  with  a  strong  solution  of  pearl  ashes 
find  add  the  phosphrous  ;  or,  use  solution  of  caustic  potash,  phos- 
phorus, and  quick  lime  ;  or  quick  lime  only,  and  phosphorus,  and  wa- 
ter. Either  of  these  methods  will  succeed.  The  first  and  the  last  of 
the  three  now  named,  are  easy  and  cheap,  and  answer  as  well  as  the 
more  troublesome  modes  usually  described  ;  the  last  process,  which 
is  the  easiest,  is  little  inferior  to  any  other.  In  all  cases,  it  would  be 
better  to  wait  till  ebullition,  when  the  vapor  will  have  expelled  the 
air  ;  then  through  the  tubulure  of  the  retort,  drop  in  the  phosphorus ; 
this  saves  the  necessity  of  any  other  precaution. 

(/.)  Phosphuret  of  lime,  with  dilute  muriatic  acid,  and  a  mod- 
erate heat ;  to  prevent  explosion,  the  retort  may  be  entirely  filled 
with  the  diluted  acid. 


*  Discovered  in  1783,  by  Gengembre.  It  is  called  also  phosphuretted  and  bi- 
phospuretted  hydrogen  gas. 

t  My  method  is  to  fill  a  small  retort,  (holding  from  4  to  6  or  8  oz.)  with  a  strong 
alkaline  solution.  Drop  in  the  phosphorus,  then  from  a  small  vial  with  a  bent  tube 
and  a  little  iron  filings  and  diluted  acid,  throw  up  as  much  hydrogen  gas,  as  will  dis- 
place the  greater  part  of  the  fluid,  keeping  the  mouth  of  the  retort  in  a  bowl  of  the 
same  solution,  then  place  the  neck  of  the  retort  under  the  shelf  of  the  tub,  and  ap- 
ply a  lamp.  It  never  fails.  A  bottle  full  of  the  solution  will  last  for  years,  as  but 
little  is  expended  at  a  time. —  Communicated,  J.  G. 

I  would  add,  that  even  when  the  air  is  not  removed,  the  only  precautions  necessary 
to  be  observed,  are — not  to  immerse  the  beak  of  the  retort  until  it  has  ceased  flashing 
in  the  interior,  "and  begins  to  shew  flame  at  the  mouth— not  to  immerse  it  deeply  at 
all,  and  to  watch  that  the  water  does  not  go  back  by  regurgitation, — Author. 


PHOSPHURETS.  441 

In  these  cases  water  is  decomposed  ;  its  hydrogen,  with  a  portion 
of  phosphorus,  forms  phosphuretted  hydrogen,  and  its  oxygen,  with 
other  proportions,  forms  phosphorous,  and  hypo-phosphorous  acid. 

2.  PROPERTIES. 

(a.)  Smell  alliaceous  ;  fires  spontaneously,  with  a  beautiful  ring  of 
smoke,  rising  and  enlarging  for  some  distance  ;  it  is  vapor  of  water 
and  phosphorous  acid ;  similar  appearances  are  sometimes  seen  dur- 
ing the  discharge  of  artillery. 

(b.)  Detonates  with  oxygen,  1^  of  oxygen  to  1  measure  of  phos- 
phuretted hydrogen  ;  only  one  bubble  of  either  gas  must  be  let  up 
into  the  other  at  once.  The  combustion  is  very  brilliant.*  If  only  1 
measure  of  oxygen  be  used,  the  product  is  phosphorous  acid,  if  1 J, 
it  is  the  phosphoric. 

(c.)  In  chlorine  and  nitrous  oxide  gases,  phosphuretted  hydro- 
gen explodes.  In  all  these  cases,  the  same  effect  is  produced,  if 
the  gas  supporting  combustion  be  let  up  into  the  phosphuretted  hy- 
drogen, and  with  oxygen  this  course  is  rather  safer. 

(d.)  Sulphurous  acid  gas,  and  phosphuretted  hydrogen  mutually 
decompose  each  other. 

(e.)  Phosphuretted  hydrogen  loses  its  spontaneous  inflammability, 
after  standing  a  short  time  ;  a  part  of  the  phosphorus  is  deposited  ; 
but  it  still  burns,  and  with  a  very  bright  light,  when  kindled  by  a  candle. 

(/.)  In  the  dark,  and  over  mercury,  it  retains  its  inflammability  a 
long  time. 

(g.)  It  is  lighter  than  common  air.  Air  being  1,  its  sp.  gr.  is  ac- 
cording to  Thomson,  .9027,  theory  and  experiment  coinciding,  for 
sp.  gr.  of  hydrogen,  -  0.0694 

And  of  phosphorus  vapor,     0.8333 

0.9027f 
Dumas  gives  it  at  1.761  5  Dalton  at  1.1. 

*  A,  represents  an  air  jar,  with  a  few  cubic 
inches  of  oxygen  gas,  standing  over  a  column  of 
water.  B,  is  a  retort,  with  slacked  lime,  phos- 
phorus, and  strong  solution  of  pearl  ashes,  the 
bubbles  of  gas  coming  singly,  but  rather  rapid- 
ly— on  depressing  the  mouth  of  the  retort,  (on 
a  particular  occasion,)  a  little  gas  accumulated, 
and  one  bubble  hung  in  the  glass  jar  without 
explosion,  but  the  next  blew  up  the  whole 
with  great  violence,  broke  all  the  contigu- 
ous glass  vessels,  shot  some  of  their  fragments 
to  the  distance  of  40  feet,  among  a  large  au-  B 
dience,  and  slightly  wounded  several  specta- 
tors ;  this  shews  the  necessity  of  extreme 
caution.— See  Am.  Jour.  Vol.  VI,  p.  187. 

t  Henry,  Vol.  1,  p.  489. 

56 


442  PHOSPHURETS. 

(h.)  Water  absorbs  a  portion  of  this  gas,  by  agitation  ;  if  thorough- 
ly deprived  of  air  at  55°,  it  absorbs  j-  of  its  bulk,  (Dalton ;)  ^ 
(Thomson.) 

(i.)  Heat,  below  boiling,  expels  it  unaltered  and  inflammable. 

(j.)  Spontaneously  decomposed  by  exposure  to  the  air;  oxide 
of  phosphorus  is  precipitated,  and  the  gas  rises  uninflammable,  (spon- 
taneously.) 

(&.)  Solution  of  this  gas  does  not  change  the  test  colors.  This 
gas  being  readily  absorbed  by  sulphate  of  copper,  and  chloride  of 
lime,  a  sure  method  is  thus  afforded  of  ascertaining  whether  it  is  con- 
taminated with  common  hydrogen. 

SI.)  Precipitates  many  metallic  solutions  in  the  state  of  phosphuret. 
m.)  Potassium  does  not  inflame  in  phosphuretted  hydrogen  gas, 
even  when  heated,  but  the  potassium  is  converted  into  a  phosphuret, 
and  2  measures  of  the  gas  become  3. 

(n.)  Decomposed  by  heat,  by  electricity,  and  by  vaporizing  sul- 
phur through  this  gas;  it  then  becomes  sulphuretted  hydrogen.* 
Phosphuretted  hydrogen  collected  in  a  jar  with  a  cap  and  stop 
cock,  blazes  when  the  jar  is  depressed  into  the  water  and  the  orifice 
opened  ;  or  if  a  bent  tube  be  attached  to  the  cap,  and  the  bubbles 
be  allowed  to  issue  from  beneath  the  water,  they  flash  as  they  break 
into  the  air.f 

OTHER    VARIETIES    OF    PHOSPHURETTED    HYDROGEN. 

1.  Sub-phosphuretted  hydrogen  gas. 

(a.)  This  is  the  gas,  already  named,  which  remains  after  the  com- 
mon phosphuretted  hydrogen  has  deposited  J  of  its  phosphorus,^,  and 
has  thus  lost  its  spontaneous  inflammability  ;  it  is  called  at  present, 
gub-phosphuretted  hydrogen,  and  by  some  proto-phosphuretted  hy- 
drogen. 

(b.)  For  perfect  combustion  it  requires  1.25  volumes  of  oxygen; 
,75  saturates  the  phosphorus,  and  .50  the  hydrogen  ;  as  the  vapor  of 
phosphorus  requires  its  own  volume  of  oxygen,  this  gas  is  inferred 
to  consist  of  1  vol.  of  hydrogen,  0.0694  +  0.75  of  a  vol.  of  phosphorus, 
0,6250  =  .(5944, 


*  We  are  not  informed  what  becomes  pf  the  phosphorus  ;  whether  it  is  precipitated 
or  remains  suspended  in  vapor. 

t  It  is  supposed  that  many  of  these  fires  which  are  said  to  be  seen  at  night,  around 
burying  grounds,  and  other  place?  where  animal  and  vegetable  substances  are  un- 
dergoing decomposition,  arise  in  part  at  least,  from  phosphuretted  hydrogen.  Trav- 
elling once,  through  a  deep  valley,  in  a  dark  night,  between  Wallingford  and 
Durham,  Conn.  I  was  surrounded  by  multitudes  of  pale  lambent  lights;  they  were 
every  moment  changing  their  position,  and  some  of  them  were  within  the  reach  of 
my  whip  ;  they  were  yellowish  and  not  intense. 

I  Thomson. — Dumas  says  one  third, 


PHOSPHURETS.  443 

2>  Hydro-phosphoric  gas. — Davy  ;  bi-hydroguret  of  phosphorus. 
—  Thomson. 

(a.)  Obtained  by  heating  solid  phosphorous  acid  away  from  air  ; 
the  hydrogen  of  the  water  of  crystallization  unites  with  a  part  of  the 
phosphorus  to  form  this  gas,  and  the  oxygen  with  another  part  to 
form  phosphoric  acid. 

(b.)  JL  distinct  gas,  not  spontaneously  inflammable ;  smell  fetid, 
but  less  so  than  that  of  the  phospburetted  hydrogen. 

c.)  JLt  300°  Fahr.  it  detonates  violently  with  oxygen  gas. 
)  Explodes  in  chlorine  with  a  white  flame. 

Water  absorbs  j-  of  its  volume. 

/.)  Sp.  gr.  .87* — more  than  twelve  times  as  much  as  that  of  hy- 
drogen gas. 

(g.)  Potassium  heated  in  it  becomes  a  phosphuret,  and  the  volume 
of  the  gas  is  doubled. 

(A.)  Sulphur  in  the  same  manner  produces  sulphuretted  hydro- 
gen gas,  equal  to  twice  the  original  volume. 

(i.)  3  volumes  of  this  gas  condense  5  of  oxygen,  1  volume  re- 
quires 2  of  oxygen  for  its  complete  combustion,  1  for  each  of  its 
constituent  principles,  forming  phosphoric  acid ;  and  with  1 J  vol. 
oxygen,  phosphorous  acid. 

(j.)   1  volume  of  this  gas  absorbs  4  of  chlorine. 

Remarks. — Mr.  Dalton  says  that  there  is  only  one  variety  of  the 
phosphuretted  hydrogen,  that  the  others  quoted  are  merely  mixtures 
of  this  with  common  hydrogen,  and  that  they  may  be  separated  by 
chloride  of  lime,  which  absorbs  the  former.  He  says  that  phosphu- 
retted hydrogen  requires  2  volumes  of  oxygen  for  saturation,  and  8 
volumes  of  water  for  its  solution, f  &c. 

It  is  inconsistent  with  the  design  of  this  work  to  discuss  the  views 
of  different  writers  on  the  subject  of  these  compounds,  particularly 
the  elaborate  researches  of  M.  Dumas. {  A  full  abstract  of  them  is 
given  by  Dr.  Ure,  in  his  Dictionary,  2d  Ed.  p.  658,  and  the  views 
of  Prof.  Rose  are  briefly  stated  by  Dr.  Turner,  2d  Ed.  of  his 
Chemistry,  p.  355.  It  is  sufficient  for  the  general  student  to  know 
that  there  are  either  several  varieties  of  phosphuretted  hydrogen,  or 
that  the  gas  which  has  been  so  long  known  by  that  name,  is  mixed 
in  different  proportions  with  common  hydrogen  gas,  which  as  al- 
ready stated,  is  the  opinion  of  Mr.  Dalton. 


*  Davy. — .9653  Thomson.  Theory  would  give  it  at  .9721 ;  twice  the  sp.  gr.  of 
hydrogen,  =  0.1388,+  sp.  gr.  of  phosphorus  vapor,  8333.— .9721. — Henry.  Mr. 
Dumas  states  it  as  1.214. 

t  Thomson's  Annals,  Vol.  XI,  p.  7. 

i  Ann.  dc  Chirn.  et  de  Phys.  Vol.  XXXI,  p.  158-. 


444  PHOSPHURETS. 

PHOSPHURET  OF  SULPHUR,  OR  SULPHURET  OF  PHOSPHORUS.* 

1.  PREPARATION. 

(«.)  It  is  unsafe  to  form  this  compound  by  melting  the  materials 
under  water,  unless  in  very  small  quantities,  say  60  or  80  grains, 
and  with  a  heat  not  over  160°  Fahr. 

(6.)  Mix  the  ingredients,  the  phosphorus  in  slices- — the  sulphur 
in  flowers,  and  place  them  in  a  tube  sealed  at  one  end,  and  loosely 
corked ;  immerse  this  in  water,  and  heat  it  gradually,  till  the  com- 
bination is  formed,  f  Or,  melt  phosphorus,  not  exceeding  30  or 
40  grains,  in  a  tube  from  J  to  f  of  an  inch  wide,  and  4  or  5 
inches  long  ;  the  sulphur  may  be  thrown  in,  in  successive  small 
pieces.  In  all  the  modes,  sulphuretted  hydrogen  is  evolved. 

2.  PROPERTIES. 

(«.)  Fusibility  greatest  when  the  proportions  are  equal — or  1J  of 
sulphur  to  2  phosphorus,  J  congeals  at  41  ;  1  of  sulphur  to  2  phos- 
phorus, at  50°  ;  with  1  to  4  at  60°  ;  sulphur  prevailing,  it  becomes 
less  fusible ;  1  of  phosphorus  to  2  sulphur  congeals  at  56°,  1  to  3 
at  99°.  Phosphorus  1,  and  sulphur  8,  or  even  30,  give  a  solid  and 
good  compound  for  lighting  matches,  but  they  unite  in  every  propor- 
tion. 

(b.)  Decomposes  water,  becomes  acid,  emits  fetid  gases,  and 
if  heated  in  contact  with  water  to  210°,  it  explodes. 

(c.)  Less  inflammable  when  formed  in  the  dry  than  in  the  humid 
ivay  ;  becomes  very  inflammable  by  kindling  it  by  a  hot  wire  in  the 
tube,  and  suffering  it  to  burn  for  a  few  minutes. 

(d.)  Olive  oil,  rubbed  with  this  compound,  and  suffered  to  stand 
in  the  cold,  dissolves  it,  as  do  the  essential  oils. 

(e.)  When  the  solution  is  perfectly  clear,  it  may  be  rubbed  on  the 
hands  with  safety,  and  appears  very  luminous  in  the  night. 

(f.)  The  solution  in  olive  oil,  mixed  in  equal  parts  with  oil  of 
turpentine,  gives  a  beautiful  shower  of  fire,  when  poured  out  in  the 
dark. 


*  For  many  interesting  particulars,  see  Nich.  Vol.  VI,  and  VII ;    Accum  and 
Briggs ;  Ann.  de  Chim.  Vol.  IV,  p.  10  ;  Quar.  Jour.  IV,  p.  361. 

t  The  young  chemist  should  be  very  much  on  his  guard  in 
forming  this  dangerous  compound  ;  the  mode  in  which  I  have 
succeeded  the  best,  has  been  to  prepare  the  materials  as  stated  t 
in  the  text,  and  then  to  hang  the  tube  through  a  piece  of  board 
laid  across  a  common  tea-kettle,  whose  lid  is  removed ;  it  con- 
tains cold  water,  and  is  placed  over  live  coals  contained  in  a 
table  furnace,  and  left  to  itself;  it  ought  not  to  be  approached 
until  the  water  has  boiled  and  grown  cold  again.  I  have,  when 
even  all  these  precautions  were  taken,  known  several  violent 
explosions,  throwing  the  kettle  to  a  distance. 

Prof.  Olmsted  remarks,  that  if  the  phosphorus  is  dried  by  blotting  paper,  and  the 
sulphur  in  a  saucer,  the  danger  of  explosion  is  greatly  diminished. 

\  Thenard  says  2  of  phosphorus  and  1  of  sulplur. 


ftl  9 


PHOSPHURETS.  445 

PHOSPHURETS  OF  THE  ALKALIES  are  scarcely  formed,  except 
the  transient  combination  by  which  phosphuretted  hydrogen  is  pro- 
duced ;  they  have  but  a  momentary  existence,  and  pass  to  the  saline 
condition. 

PHOSPHURET  OF  LIME. 

1.  PREPARATION. 

(a.)  A  coated  glass  or  earthen  tube  is  partly  filled  with  good  lime, 
in  pieces,  occupying  the  middle  ;  phosphorus  is  placed  at  one  end, 
which  is  stopped  with  fire  lute ;  the  other  end  is  closed  with  solid 
chalk ;  lay  it  across  a  furnace,  and  when  the  lime  is  red  hot,  draw 
the  phosphorus  into  the  heat,  it  sublimes,  and  the  compound  is  form- 
ed ;  it  must  be  kept  close  from  the  air. 

2.  PROPERTIES. 

Of  an  auburn  brown  color. 

Thrown   into  water,  emits  phosphuretted  hydrogen,  which 
flashes  in  the  air. 

(c.)  Place  some  of  it  in  a  dish  of  water,  and  bring  over  it  quickly 
a  jar  of  common  air,  which  produces  a  pretty  fire  work ;  we  should 
be  on  our  guard  against  explosion,  which,  especially  if  oxygen  gas 
be  used,  is  very  liable  to  happen. 

(d.)  It  is  said,f  that  lime  and  phosphorus  stratified  in  a  long  vial, 
buried  in  sand  to  the  neck,  and  gradually  heated,  keeping  just  be- 
low redness  till  the  combination  is  formed,  will  answer  as  a  substi- 
tute for  the  tube  experiment,  and  then  the  phosphuret  may  be  kept 
in  the  same  vial.J 

(e.)  It  is  very  possible  that  this  substance  is,  at  least  in  part,  a 
phosphuret  of  calcium  ;  but  no  accurate  experiments  have  been 
made  to  determine  this  point. 

(/.)  If  phosphorus  be  sublimed  through  carbonate  of  lime,  the 
carbonic  acid  is  decomposed,  and  charcoal  deposited. 

Remark. — From  half  an  ounce  of  good  phosphuret  of  lime,  60 
cubic  inches  of  phosphuretted  hydrogen  gas  are  obtained,  by  the 
agency  of  muriatic  acid. 

####•*##• 

The  phosphurets  of  baryta  and  strontia  may  be  formed  in  the 
same  manner,  but  they  possess  no  properties  that  are  peculiar,  ex- 
cept that  the  phosphuret  of  baryta^  is  employed  for  the  formation  of 
the  hypo-phosphorous  acid. 

*  If  languid,  warm  water  makes  it  succeed  brilliantly,  and  sulphuric  acid,  (strong) 
added  to  the  mixture,  has  the  same  effect.  Muriatic  acid  has  a  similar  effect,  but 
not  with  so  much  energy. 

t  Aikins'  Diet.  Vol.  II,  p.  214. 

+  This  has  not  succeeded  well  with  me  ;  the  phosphorus  is  vaporized  before  the 
lime  is  sufficiently  heated. 

§  See  Dr.  Pearson's  account  of  the  phosphurets  in  the  Phil.  Trans. 


446  NITROGEN. 

SEC.  V. — NITROGEN. 

COMBINATIONS  OF  NITROGEN  AND  PRECEDING  SIMPLE  BODIES. 
COMPOUNDS  OF  NITROGEN  WITH    OXYGEN,    AND  THE  COMBINA- 
TIONS OF  THESE  WITH  PRECEDING  BODIES. 

Remarks. — As  it  seemed  difficult  to  advance  at  all  without  a 
knowledge  of  the  composition  of  the  atmosphere,  the  history  of  nitro- 
gen was  given  in  connexion  with  that  subject.  It  now  remains  to 
detail  the  history  of  the  other  Compounds  into  which  nitrogen  enters, 
in  connexion  with  oxygen,  and  it  seeins  to  me  that  the  properties 
of  this  very  singular  class  of  bodies  will  be  best  understood  by  taking 
them  in  the  following  order. 

NITRIC  ACID. — -NiTRic  OXIDE  GAS,  (nitrous  gets.) — NITROUS 
ACIDS. — NITRATES  OF  ALKALIES. — NITROUS  OXIDE,  (exhilirating 
gas.) — NITRATES  OF  EARTHS. — NITRITES  ;  to  be  concluded  by  a 
recapitulation  of  the  composition,  fyc.  of  the  nitric  compounds. 

NITRIC  ACID. 

1.  HISTORY. — First  obtained  by  distilling  a  mixture  of  nitre  and 
clay.     The  discoverer  was  Raymond  Lully,  a  chemist  of  the  island 
of  Majorca,  born  in  1235.     Basil  Valentine,  in  the  fifteenth  century, 
describes  the  process  more  minutely,  and  calls  the  acid  water  of  nitre  ; 
subsequently  it  was  called  spirits  of  nitre  and  aquafortis  ;  the  latter 
is  still  the  name  in  the  shops.      Called  nitric  acid  by  the  French 
chemists,  in  1782;  because  it  is  obtained  from  nitre.*     On  the  prin- 
ciples of  the  nomenclature,  it  would,  at  that  time,  have  been  called 
azotic  acid,  and  the  name  azote  was  altered  to  nitrogen  to  make  the 
terminology  consistent. 

2.  PREPARATION. 

(a.)  For  information  merely,  the  original  experiment  of  Mr.  Cav- 
endish may  be  repeated. f  In  that  case,  it  was  formed  by  electrizing 
for  a  great  length  of  time,  with  many  thousand  shocks,  a  mixture  of 
oxygen  and  nitrogen  gases,  in  the  proportion,  by  measure,  of  5  parts 
of  oxygen  to  3  of  common  air,  or  7  oxygen  to  3  nitrogen,  or  common 
air  by  itself.  J  It  may  be  done,  over  quicksilver,  in  a  glass  tube,§ 
furnished  with  gold  or  platinum  wires ;  caustic  potash,  introduced 
before  electrization,  will  absorb  the  acid  as  it  is  formed,  and  thus 

*  Familiarly  called  saltpetre. 

t  See  Phil.  Trans.  Vol.  LXXV,  1785. 

'  t  Oxygen  and  azotic  gas  were  mixed  by  Mr.  Cavendish,  in  the  proportion  of  416 
of  the  former,  to  914  of  the  latter,  in  bulk,  in  one  experiment,  and  in  another,  in  the 
proportion  of  1920 : 4860,  and  (Phil.  Trans.  1785,)  he  converted  them  totally  into 

WITRIC  ACID. 

§  A  distinguished  chemist,  in  London,  informed  me,  in  1805,  that  he  and  a  noble- 
man who  was  his  pupil,  had  labored  during  a  month  to  produce  nitric  acid  by  the  ori- 
ginal experiment  of  Mr.  Cavendish^  but  without  success.  This  goes  only  to  prove 
that  it  is  a  difficult  process,  for  the  name  of  Mr.  Cavendish  is  sufficient  authority  for 
any  thing  which  he  asserts. 


NITRIC  ACID.  447 

nitre  will  be  produced,  from  which  the  acid  may  be  extracted.  Min- 
gled in  proper  proportions,  the  gases  nearly  disappear,  in  conse- 
quence of  their  combination. 

(b.)  The  usual  process  for  nitric  acid.* — A  large  retort,  with  an 
adopter,  tubulated  receiverf  and  sand  heat ;  the  lute,  is  clay5  sand  and 
flour,  equal  measures,  mixed  and  kneaded  together ;  proportions  of 
the  salt  and  acid,  nitre  6,  sulphuric  acid  4  to  6 ;  the  nitre  in  fragments : 
if  the  receiver  is  not  tubulated  there  should  be  an  opening  through  it 
for  gas  to  escape;  heat  slowly  raised,  receiver  kept  cool;  there 
should  be  no  water  in  it,  if  we  would  obtain  a  strong  acid ;  the  pro- 
cess lasts  one  hour,  or  two  or  more,  according  to  the  quantity ;  there  is 
some  red  gas  at  the  beginning,  and  much  towards  the  end  ;  the  retort 
is  clear  in  the  middle  of  the  experiment,  and  when  the  residuum 
puffs  up,  we  stop  the  process.  To  extract  the  caput  mortuum,  J  warm 
water  is  poured  in  very  cautiously,  and,  at  first,  in  very  small  portions, 
for  there  is  great  heat  and  ebullition ;  proceed  carefully  till  the  super- 
sulphate  of  potassa  is  thus  dissolved ;  if  left  in,  it  almost  infallibly 
breaks  the  retort  by  crystallizing  ;  the  excess  of  acid  may  be  driven 
away  by  heat,  or  neutralized  by  chalk,  and  then  crystals  of  sulphate 
of  potassa  will  be  obtained. 

(c.)  Nitric  acid  is  freed  from  muriatic,  and  in  a  good  degree  from 
the  sulphuric,  by  nitrate  of  silver  ;§  the  sulphuric  acid  is  better  re- 
moved by  distilling  it  again  from  J  of  the  original  quantity  of  very  pure 
nitre. 

(d.)  Nitrate  of  baryta  also  separates  the  sulphuric  acid ;  it  must 
be  re-distilled  off  from  the  precipitate,  leaving  J  or  T\  in  the  retort. 

(e.)  Pure  nitre  is  prepared  by  dissolving  and  crystallizing  nitre 
several  times,  the  last  time  with  the  addition  of  nitrate  of  silver,  to 
precipitate  the  muriatic  acid.  Such  nitre  will,  if  the  salt  does  not  soil 
the  neck  of  the  retort,  and  the  heat  is  cautiously  raised,  and  is  not 
raised  too  high,  give  pure  nitric  acid  in  the  first  process. 

(/.)  The  colored  acid  may  be  made  clear  by  long  and  cautious 
heating,  to  expel  the  nitric  oxide  gas,  and  a  receiver  may  be  used  to 
save  any  acid  that  rises.  The  acid  is  more  easily  cleared  by  a  little 
black  oxide  of  manganese,  placed  in  the  retort  which  imparts  oxygen 
and  converts  the  nitrous  into  nitric  acid.  Probably  any  other  nitrate 
would  answer  to  afford  nitric  acid,  but  the  nitrate  of  potash  is  the  best.|| 

*  Nitre  may  be  decomposed  by  sulphuric  acid  in  small  quantities,  with  a  naked  glass 
retort,  over  a  lamp  or  live  coals,  and  the  adopter  is  not  indispensable,  as  the  receiver 
is  very  little  heated  in  the  process. 

t  Furnished  with  a  bent  tube  if  you  wish  to  collect  the  gases  evolved. 

t  An  old  fanciful  name  given  to  the  solid  residuum  from  distillation. 

§  Or  nitrate  of  lead  ;  but  nitrate  of  silver  is  preferable. 

|)  Dr.  Thomson,  (First  Principles,  Vol.  I,  p.  107,)  says  that  pure  nitre  is  anhy- 
drous, and  that  if  a  little  water  be  mechanically  lodged  between  the  plates  of  the 
crystals,  it  is  easily  dissipated  by  a  moderate  heat  or  by  fusion.  When  such  nitre  in 
the  proportion  of  12|  parts  is  decomposed  by  6  \  parts  of  the  strongest  sulphuric 


448  NITRIC  ACID. 

3.  PROPERTIES. 

(a.)  Its  sp.  gr.  is  usually  1.5  or  1.55  ;  it  has  been  obtained  as  high 
as  1.62,  by  Proust  ;f  supposed  to  be  in  its  pure  state  an  acid  gas  of 
sp.  gr.  2440,  air  being  1000 ;  this  acid  gas  with  water  forms  the 
common  acid;  that  having  the  sp.  gr.  1.55,  contains  nearly  86  per 
cent,  of  acid,  and  14  water. 

Table  of  the  strength  of  nitric  acid,  from  Thomson's  First  Prin- 
ciples, Vol.  I,  p.  114. 

Equiv.  of  acid.       Equiy.  of  water.  Acid  in  100.  Sp.  Gr. 

1     -       -  1     -       -         85.714     -       -         1.5500 

1  2         -  75.000         -       -     1.4855 

1     -  3     -  66.668     -       -         1.4546 

1         -       -       4         -       -     60.000         -       -     1.4237 
1     -  5     -  54.545     -       -         1.3928 

1         -       -       6         -  50.000         -       -     1.3692 

1     -  7     -  46.260     -       -         1.3456 

1  8         -  42.857         -       -     1.3220 

1     -  9     -  40.000     -       -         1.3032 

1         -       -     10         -       -     37.500         -       -     1.2844 
1     -       -         11     -       -         35.294     -       -         1.2656 
1         -       -     12         -       -     32.574         -       -     1.2495 
1     -       -         13     -       -         31.579     -       -         1.2334 
1         -       -     14         -       -     30.000         -       -     1.2173 
1     -       -         15     -       -         28.571     -       -         1.2012 
(b.)  Hydro-nitric  acid,  as  it  is  called,  is  a  pale  colorless  fluid,  like 
water,  with  a  pungent  odor,  and  it  emits  smoke  in  the  air. 
(c.)  It  has  all  the  acid  properties  in  perfection. 
(d.)  Highly  corrosive,  and  turns  the  skin  yellow, 
(e.)  Boils  at  248°,  and  is  distilled  without  change  ;  but  this  boil- 
ing point  belongs  to  acid  of  the  sp.  gr.  1.42,  containing  acid  .60  and 
water  40. 


acid,*  we  obtain  the  strongest  nitric  acid,  with  sp.  gr.  1.55.  When  the  proportion  of 
sulphuric  acid  is  doubled,  the  retort  is  not  so  liable  to  be  broken,  but  the  nitric  acid, 
obtaining  a  larger  supply  of  water  from  the  sulphuric  acid,  is  of  course  weaker. 
When  12|  parts  sulphuric  acid  are  mixed  with  12|  parts  of  pure  anhydrous  nitre,  the 
whole  of  the  nitric  acid  is  obtained,  but  of  the  sp.  gr.  1.4855,  and  its  composition  is  1 
equivalent  acid  and  2  water.  In  the  London  Pharmacopeia,  equal  parts  of  nitre  and 
sulphuric  acid  are  ordered ;  this  contributes  to  the  formation  of  a  bi-sulphate  of  pot- 
ash, which  is  said  to  be  necessary  to  the  entire  decomposition  of  the  nitre,  and  af- 
fords two  proportions  of  water,  which  are  required  to  condense  the  whole  of  the 
nitric  acid.  The  Edinburgh  Pharmacopeia  and  the  manufacturers  use  three  fourths 
or  four  fifths  of  sulphuric  acid,  and  these  proportions  are  the  best. 

*  It  is  well,  before  using  it,  to  heat  the  sulphuric  acid  nearly  to  its  boiling  point, 
to  expel  the  water  it  may  have  imbibed. 

t  Gay-Lussac  says,  (Ann.  de  Chim.  et  de  Phys.  Vol.  I,  p.  396,)  that  1.510,  at  18° 
centigrade,  is  the  heaviest  that  had  then,  (1816,)  been  obtained. 


NITRIC  ACID.  44Q 

Jlny  acid,  either  weaker  or  stronger,  boils  at  a  lower  temperature;  if 
weaker,  it  is  strengthened,  if  stronger,  it  is  weakened  by  boiling  ;  and 
acids  of  all  degrees  of  strength  come,  by  continued  boiling  to  sp.  gr. 
1.42,  which  seems  to  be  the  strongest  combination  of  acid  and  water. 
Acid  of  sp.  gr.  1.369,  contains  half  its  weight  of  water  ;  that  of  sp. 
gr.  1.30,  has  acid  40  and  water  60,  and  boils  at  236°.* 

(/.)  Frozen  at  2°  below  0,  Fah.  if  of  sp.  gr.  1.3.  When  either 
stronger  or  weaker,  it  requires  a  much  more  intense  cold,  as  much,  in 
some  cases,  as  to  freeze  mercury. f 

(g.)  Exposure  to  light,  colors  it  red,  while  oxygen  gas  is  given 
out,  provided  it  be  strong  ;  and  this  happpens  when  it  is  weak,  if  it 
be  previously  mixed  with  sulphuric  acid. 

(A.)  Decomposed  into  oxygen  and  nitrogen  gases,  or  nitric  oxide 
gas,  by  being  passed  in  vapor  through  a  red  hot  earthen  tube,  and 
the  stronger  the  acid  the  more  readily  it  is  decomposed.  A  pendent 
candle  just  blown  out,  is  promptly  relighted  by  being  plunged  into  the 
mixed  oxygen  and  nitrogen  ;  these  may  be  analyzed  by  any  of  the 
eudiometrical  methods,  and  their  proportion  ascertained.  They  will 
be  found  to  be  in  nearly  the  reversed  proportions  of  the  atmosphere. 
Some  nitric  oxide  gas  usually  comes  over  and  produces  red  fumes  of 
nitrous  acid,  which  are  soon  absorbed  by  the  water,  and  leave  the  ox- 

(gen  and  nitrogen  mixed.  The  decomposition  of  the  solid  nitrates 
y  ignition  affords  similar  results  ;  nitrate  of  ammonia,  is  however  an 
exception,  as  will  appear  in  its  proper  place. 

(i.)  Causes  ice  and  snow  to  melt,  producing  cold  ;  4  parts  strong- 
est nitric  acid  with  7  of  snow,  sink  the  mercury  from  -f  32  to  — 30°  , 
see  tables  of  freezing  mixtures. 

(j.)  Attracts  water  from  the  air  and  becomes  weaker,  but  not  in 
an  equal  degree  with  sulphuric  acid. 

(/c.)  Acid  2,  -f-  water  1,  at  common  temperature,  raise  the  therm. 
112°,  but  if  more  water  is  added,  this  mixture  lowers  the  tempera- 
ture. Nitric  acid,  58  measures,  of  sp.  gr.  1.5,  mixed  with  42  of 
water,  raises  the  temperature  from  60°  to  140°,  Fahr.  and  on  cool- 
ing, the  100  measures  occupy  92.65.J 

(I.)  More  or  less  affected  and  decomposed  by  all  combustibles,  and 
by  most  metals. 

(m.)  It  explodes  with  hydrogen  at  a  high  degree  of  heat ; 
caution  is  required ;  it  is  best  shown  by  passing  the  hydrogen  gas 
from  a  flask,  by  means  of  a  tube  bent  twice  at  right  angles,  through 
nitre  melted  in  a  crucible,  when  there  is  a  slight  explosion,  and  a 
flash  at  the  passage  of  every  bubble  of  gas  ;  some  caution  is  requisite. 


Dalton.     Thomson.     Henry.  t  Cavendish,  Phil.  Trans.  1788. 

Ure,  quoted  by  Turner. 

57 


I 


4f>0  NITRIC  AC  It). 

(?i.)  Boiled  on  sulphur,  sulphuric  acid  is  formed,  but  without 
combustion. 

(o.)  Poured  on  charcoal,  there  results  a  vivid  inflammation;  it  is 
best  to  pound  ignited  charcoal  taken  immediately  from  the  fire ;  put 
it  into  a  worthies  glass  vessel  or  a  crucible,  and  add  the  acid  gradu- 
ally. Lamp  black,  or  the  charcoal  of  oils  inflames  more  easily  than 
common  charcoal,  but  a  mixture  of  the  two  more  easily  than  either 
alone. 

(p.)  Phosphorus  is  converted  into  phosphoric  acid  by  the  nitric  ; 
if  weak,  it  merely  boils  with  red  fumes  of  nitrous  acid  $  if  very  strong, 
and  especially  if  warm,  it  burns  with  a  splendid  combustion;  it  is 
thrown  about  in  jets  of  fire  and  requires  great  caution  ;  to  render  it 
the  more  beautiful,  a  tall  narrow  deep  vessel  should  be  used,  but 
when  the  quantity  of  both  substances  is  considerable,  there  is  some- 
times a  dangerous  explosion.* 

(q.)  If  phosphoric  acid  is  desired^  the  common  aquafortis  is  strong 
enough  ;  it  may  be  gently  heated  ;  the  phosphorus  is  added  in  pieces, 
and  when  they  are  no  longer  dissolved,  and  readily  take  fire  on  com- 
ing to  the  surface,  the  process  is  through. 

(r.)  Heat  will  expel  any  remaining  nitric  acid,  and  if  pushed  far 
enough  in  a  platinum  vessel,  we  obtain  glacial  phosphoric  acid. 

(s.)  The  easily  oxidable  metals,  iron,  tin,  zinc,  copper,  &ic.  de- 
compose the  acid  powerfully,  especially  if  hot. 

(t.)  Very  strong  nitric  acid,  poured  from  a  glass  fixed  to  a  pole,  fires 
oil  of  turpentine,  and  other  volatile  oils — the  pole  is  for  safety.  A 
little  sulphuric  acid  is  mixed  with  the  nitric,  to  concentrate  it  by  re- 
moving a  portion  of  water  which  it  contains.  The  drying  oils  do  not 
need  the  addition  of  sulphuric  acid. 

4.  COMPOSITION  AND  COMBINING  WEIGHT. — When  we  have  fin- 
ished the  history  of  the  compounds  of  nitrogen  and  oxygen,  we  will 
review  that  of  nitric  acid,  which  cannot  perhaps  be  fully  understood 
without  an  acquaintance  with  all  the  acids  and  oxides,  which  have 
nitrogen  for  their  basis.  We  may  state  at  present,  that  the  propor- 
tions of  the  elements  of  nitric  acid,  by  weight,  are, 

74.13     oxygen,       -       -     286     by  volume,  nearly  250 
25.87     nitrogen,  100  "  "    '    100 

100.00  386 


*  This  circumstance  has  happened  so  often  in  my  own  experience,  with  nitric  acid 
distilled  from  very  pure  nitre,  with  two  thirds  its  weight  of  sulphuric  acid,  and  with- 
out any  water  in  the  receiver,  that  I  cannot  but  repeat  the  caution  that  the  operator 
should  be  much  on  his  guard.  With  a  stick  of  phosphorus  as  long  as  a  finger  drop- 
ped into  2  or  3  oz.  of  strong  nitrous  acid,  1  have  known  explosions  like  those  of  a 
swivel,  and  the  fragments  of  glass  have  wounded  persons  at  a  considerable  distance. 
See  Am.  Jour.  for'Dr.  Hare's  experience. 


NITRIC  ACID.  451 

and  its  constitution,  5  equivalents  of  oxygen  —40,  and  1  of  nitrogen 
=  14,  its  own  equivalent  being  therefore  54.* 

Liquid  nitric  acid,  sp.  gr.  1.50,  contains  2  proportions  of  water, 
18  +  54  =  72  for  the  representative  number. 

Dr.  Thomson  assigns  the  sp.  gr.  3.75,  to  the  dry  gaseous  acid, 
and  this  number  is  produced  by  multiplying  .06944,  the  specific 
weight  of  hydrogen,  by  54,  that  of  nitric  acid. 

5.  POLARITY. — In  the  galvanic  circuit,  this  acid  is  attracted  to  the 
positive  pole,  and  is  therefore  electro-negative. 

C.  USES. 

(a.)  The  nitric  acid  is  a  very  important  agent  in  chemistry. 
From  its  yielding  its  oxygen  with  so  much  facility,  it  is  often  em- 
ployed to  oxidate  substances  of  various  kinds,  and  particularly  several 
of  the  acids  are  formed  in  this  way.  It  attacks  and  decomposes  all 
vegetable  and  animal  substances,  giving  oxygen  to  their  carbon,  to 
form  carbonic  acid,  and  to  their  hydrogen  to  form  water. 

(b.)  It  is  also  much  used  in  the  arts ;  by  engravers  in  etching 
their  copper  plates  ;  in  the  solution  of  metals,  and  in  dyeing  ;  es- 
pecially with  muriatic  acid,  to  prepare  tin  as  a  mordant  for  cochineal, 
to  produce  the  scarlet ;  and  in  forming  and  fixing  other  fine  colors. 
It  is  employed  in  medicine,  particularly  in  liver  diseases  ;  as  an  auxili- 
ary in  some  other  cases,  both  internally  and  externally,  but  in  the 
latter  case,  diluted,  so  as  merely  to  prick  the  skin  ;  as  a  very  valuable 
remedy  in  fevers — typhus,  petechial  and  malignant ;  and  as  a  tonic. 
It  is  diluted  to  such  a  degree,  as  to  be  only  agreeably  acid,  and  it  may 
be  qualified  By  sugar  and  aromatics. 

The  diluted  nitrous  acid  of  the  Edinburgh  and  Dublin  pharmaco- 
peias, is  composed  of  equal  weights  of  nitrous  acid  and  water. 

(c.)  Vapor  of  nitric  acid  expelled  from  nitrate  of  potassa  by  sul- 
phuric acid,  is  used  in  fumigations  to  counteract  febrile  effluvia ; 
it  appears  to  possess  a  good  deal  of  efficacy  in  that  way,  and  is 
not  inconvenient  to  the  patient,  to  whose  bed  side  it  may  be  carried 
without  harm ;  no  heat  should  however  be  applied,  as  it  will  then 
emit  very  suffocating  vapors  of  nitrous  acid.  Half  an  ounce  of  nitre 
is  mixed  with  2  drachms  of  sulphuric  acid,  and  the  vapor  from  this 
will  fill  ten  cubic  feet.  For  this  application,  Dr.  Carmichael  Smith 
received  from  the  British  Parliament,  a  reward  of  5000  pounds  ster- 
ling. 

(d.)  It  is  one  of  the  great  acids  of  commerce.  It  forms  nitrates  with 
the  salifiable  bases.  All  its  salts  are  soluble ;  it  is  separated  from 
them  all  in  a  state  t)f  decomposition,  by  heat,  and  the  bases,  ammonia 
excepted,  are  left  behind. 


*  Henry,  Vol.  I,  p.  324;  Thomson's  First  Priii.   Vol.  I,  p.  112;  Ann.  of  Philos. 
N.S.  VIII,  299. 


452  DEUTOXIDE  OF  NITROGEN. 

7.  MISCELLANEOUS — In  the  arts,  copperas  calcined  to  redness,  is 
mixed  in  equal  quantities  with  dried  and  purified  nitre  ;  the  distilla- 
lation  is  performed  in  an  earthen  retort  or  an  iron  pot  with  an  earth- 
en head,  and  a  very  strong  fuming  acid  is  thus  obtained,  called  aqua 
fords.  If  the  materials  have  not  been  before  heated,  they  will  afford 
water  and  a  diluted  acid  which  fumes  very  little  ;  it  is  called  single 
aqua  fortis.  The  sulphate  of  potassa  is  separated  by  solution,  and 
the  oxide  of  iron  is  sold  for  polishing  metals  ;  it  is  called  colcothar. 
On  the  continent  of  Europe,  they  use  clays,  boles  and  other  earths 
containing  silex  ;  the  affinity  exerted  by  these  earths,  towards  the  al- 
kali of  the  nitre  decomposes  the  latter  at  a  red  heat.  As  crude  nitre 
is  employed,  the  acid  which  is  called  spirit  of  nitre,  is  contaminated 
with  muriatic  acid. 

The  French  distil  the  nitric  acid  in  large  cast  iron  cylinders,  but 
when  iron  is  used,  more  of  the  nitric  acid  is  decomposed,  and  there 
is  of  course  more  nitrous  acid  produced. 

The  corrosive  fumes  of  nitrous  acid  are  carefully  avoided  in  the 
manufactories;  they  sometimes  cause  the  workmen  to  spit  blood. 
The  double  aqua  fortis  is  half  as  strong  as  pure  nitric  acid ;  and  sin- 
gle aqua  fortis  being  half  as  strong  as  double,  is  of  course  one  fourth 
the  strength  of  the  strongest  acid.  Nitric  acid  is  distinguished  by 
its  ready  action  on  copper  and  mercury ;  by  forming  nitre  with  potash, 
and  nitro-muriatic  acid  with  muriatic  acid,  and  thus  becoming  capa- 
ble of  dissolving  gold,*  by  bleaching  a  very  dilute  solution  of  indigo, 
if  in  the  proportion  of  7|oj  or  turning  it  yellow  if  ^^,  when  a  few 
drops  of  sulphuric  acid  are  added  ;  also  by  the  scintillation  which  it 
produces  when  dropped  upon  ignited  charcoal.  For  economical 
purposes,  100  good  nitre,  60  strong  sulphuric  acid,  and  20  of  water, 
form  a  good  proportion. 

Dr.  Ore  states,  as  the  result  of  his  own  experiments,  that  if  the 
respective  terms  of  dilution  of  nitric  acid  with  water,  be  taken  as  an 
arithmetical,  the  densities  will  be  in  a  geometrical  series. f 

In  its  concentrated  state,  it  is  a  deadly  poison,  corroding  and  de- 
stroying the  animal  organs. 

NITRIC    OXIDE    GAS NITROUS    GAS OR   DEUTOXIDE    OF    NITROGEN. 

1.  REMARKS. — In  the  strictness  of  logical  arrangement,  this  oxide 
should  be  described  after  the  protoxide  or  exhilirating  gas,  and  both 
of  them  before  nitric  acid,  but  as  it  is  obtained  by  the  decomposition 
of  the  latter,  its  history  will  probably  be  most  intelligible  if  intro- 
duced here. 

*  But  muriatic  acid  produces  a  similar  iluid  with  the  chlorates  and  bromates. 
t  Diet,  2d  Ed.  p.  57. 


DEUTOXIDE  OF  NITROGEN. 

2.  HISTORY  AND  NAME. — It  appears  from  Dr.  Hole's  vegetable 
statics,   that  he  obtained  this  gas  more  than  a  century  ago,  hut  Dr. 
Priestley  first  examined  its  properties  with  attention  in  1772.*     He 
called  it  nitrous  air;  it  is  called   also  nitrous  gas,   and  nitric  oxide 
gas,  and  deutoxide  of  nitrogen.     The  two  last  names  being  the  most 
proper  will  be  employed,   and  for  brevity  the  term  nitric  oxide  will 
be  commonly  used. 

3.  PREPARATION. 

(a.)  It  is  best  obtained  by  the  action  of  nitric  acid  upon  mercury 
or  copper:  for  both  economy  and  purity  the  latter  is  preferred. 

(b.)  Nitric  acid,  sp.gr.  1.2  or  1.3,  is  poured  upon  cuttings  of 
copper.  With  shears  like  those  used  by  the  tinmen,  cut  sheet  copper 
into  pieces  of  such  size  that  they  will  easily  slide  into  a  glass  retort ; 
add  common  aqua  fortis,  or  any  of  the  varieties  of  nitric  acid  of  the 
shops,  till  the  copper  is  more  than  covered ;  then  add  hot  water, 
by  little  and  little,  till  the  action  comes  on  ;  let  the  first  red  vapors  es- 
cape, and  when  the  neck  of  the  retort  is  nearly  clear  of  the  red  color 
the  gas  may  be  saved. f 

(c.)  If  any  of  the  copper  clippings  are  left,  they  may  be  rinsed 
with  water  and  allowed  to  remain  in  the  retort  for  another  operation. 

(d.)  If  a  diluted  acid  be  used,  the  heat  of  a  lamp  or  of  a  few  coals 
may  be  employed.  In  general,  the  gas  comes  rather  suddenly;  con- 
tinues to  flow  rapidly  for  a  few  minutes  and  then  remits;  it  is  of 
little  use  to  urge  it  with  heat  beyond  this  point ;  some  gas  may  indeed 
be  obtained,  but  it  appears  to  be  principally  that  which  was  dissolved 
in  the  nitric  acid,  and,  although  there  may  be  an  active  ebullition, 
little  is  disengaged  besides  aqueous  vapor. 

(e.)  Jin  economical  process  for  obtaining  nitric  oxide  gas  is,  to  mix 
sulphuric  acid  and  nitre  in  the  proportions  to  afford  nitric  acid,  and 
then  to  add  to  the  mixture  some  pieces  of  copper.  J 

(f.)  THEORY  of  the  process. — The  nitric  acid  imparts  oxygen  to 
the  copper  and  converts  it  into  peroxide,  which  unites  with  a  portion 
of  acid  that  has  not  been  decomposed  and  forms  nitrate  of  copper ; 
the  nitric  oxide  contains  all  the  nitrogen  of  the  acid  decomposed  and 
as  much  of  the  oxygen  as  remains  after  the  oxidation  of  the  cop- 
per. 


*  Priestley  on  Air. 

t  The  contrast  presented  by  the  green  solution  of  the  copper  and  the  red  vapor 
of  nitrous  acid  is  very  striking;  the  solution,  which  will  be  nitrate  of  copper,  (usu- 
ally with  excess  of  acid,)  should  be  saved  for  future  uses. 

t  In  some  of  the  processes  for  nitric  oxide,  a  portion  of  nitrous  oxide,  and  even  of 
nitrogen,  is  evolved. 


454  DEUTOX1DE  OF  NITROGEN. 

(g.)  Specific  gravity ;  air  being  1.  it  is  1.041,  and  100  cubic  inches 
at  60°  Fahr.  and  30  inches  of  the  barometer  weigh  31.770*  grains ; 
compared  with  hydrogen  its  weight  is  15. 

4.  COMPOSITION. 

(a.)  Potassium,  heated  in  this  gas,  abstracts  50  per  cent,  of  oxy- 
gen and  leaves  the  same  quantity  of  nitrogen;  as  50  cubic  inches  of 
oxygen  weigh  16.944  grains,  and  50  of  nitrogen  14.826,  its  weight 
is  plainly,  for  100  cubic  inches,  31.770,  as  stated  above.  As  there 
is  no  condensation  attending  the  union  of  the  gases  which  unite  in 
equal  volumes,  we  easily  obtain  the  specific  gravity  by  calculation ; 
thus  the  specific  gravity  of  oxygen  gas,  air  being  1,  is  -  1.1111 
that  of  nitrogen  gas  is  .9722  -  .9722 

The  sum  of  which  2.0833  divided  by  2  =  1.041. 
By  volume,  therefore,   this  gas  consists  of  50  oxygen  and  50  nitro- 
gen; by  weight  of  53.4  oxygen   and  46.6  nitrogen;  the  difference 
between  the  number   expressing  the  weight  and  the  volume  is  owing 
to  the  difference  in  the  specific  gravity  of  the  two  gases. 

(b.)  Heat,  applied  in  porcelain  tubes,  and  electric  sparks  decom- 
pose this  gas  ;  the  product  resembles  common  air,  and  a  portion  of 
the  original  gas  is  left  undecomposed. 

(c.)  Iron,  zinc,  tin,  arsenic,  phosphorus,  charcoal  and  the  alkaline 
sulphurets,  by  abstracting  oxygen,  convert  it  either  into  nitrous  oxide 
or  nitrogen. 

5.  CONSTITUTION. — The  equivalent  number  of  this  gas  is  obtain- 
ed by  adding  14,   which  is  the  number  for  nitrogen,   to  16,  which 
represents  two  equivalents  of  oxygen,  and  30  therefore  represents  the 
nitric  oxide. 

6.  PROPERTIES. 

(a.)  Invisible,  colorless,  and  permanently  elastic. 

(b.)  Not  much  absorbed  by  water,  unless  previously  boiled,  when 
it  takes  up,  by  agitation,  about  TV  of  its  bulk,  which  is  again  expelled 
by  ebullition. f  Dr.  Turner  states  the  absorption  at  1  or  about  11 
per  cent.  J 

(c.)  Very  hostile  to  life;  warm  blooded  animals,  immersed  in  it, 
are  killed  almost  instantly,  and  it  destroys  the  irritability  of  the  heart. 
It  kills  by  suffocation  and  by  excoriation.  It  becomes  nitrous  acid 


*  Its  weight  was  formerly  stated  by  Sir  H.  Davy  at  34.26  grains. 

t  The  impregnated  water  is  said  to  generate  nitrate  of  ammonia  after  long  keep- 
ing ;  this  is  perhaps  not  extraordinary,  as  all  the  elements  are  present,  namely,  hy- 
drogen and  oxygen  in  water,  arid  oxygen  and  nitrogen  in  the  nitric  oxide. 

1  Elements,  p.  186. 


DEUTOXIDE  OF   NITROGEN.  455 

by  meeting  with  the  oxygen  in  the  air,  in  the  cavities,  and  excites 
the  glottis  to  violent  spasmodic  action  with  most  distressing  irritation.* 

(d.)  Action  on  combustibles. — This  is  very  various;  some  com- 
bustibles that  burn  in  common  air,  do  not  burn  in  this  gas,  as  a 
candle,  sulphur,  and  most  common  combustibles,  which,  although  on 
fire,  are  extinguished  by  immersion  in  nitric  oxide. 

Phosphorus,  if  previously  kindled,  burns  with  great  energy,  but  it 
may  be  melted  in  this  gas  without  inflaming.  Homberg's  pyro- 
phous  is  spontaneously  inflamed. 

Charcoal,  previously  ignited,  takes  fire,  but  burns  feebly.-^  Hydro- 
gen gas,  mingled  with  the  nitric  oxide,  does  not  explode  by  a  lighted 
candle,  but  burns  quietly,  with  a  greenish  white  flame,  of  peculiar  and 
agreeable  hue,  which  is  modified  between  that  of  the  yellow  vapors 
of  nitrous  acid,  and  the  pale  bluish  flame  of  the  hydrogen. 

Carburetted  hydrogen — no  explosion,  except  between  7  measures 
of  nitric  oxide  gas,  and  1  of  the  olefiant. 

Spongy  platinum  acts  upon  a  mixture  of  hydrogen  gas  with  nitric 
oxide,  in  proper  proportions ;  acid  and  nitrogen  and  watery  vapor  are 
evolved. 

Ammonia  100  parts,  and  this  gas  150,  detonate  by  the  electric 
spark,  and  by  a  spontaneous  action,  nitrogen  is  liberated  in  the 
course  of  a  month.  J 

(e.)  Action  on  oxygen  ga&. — This  is  the  most  interesting  of  all 
the  relations  of  nitric  oxide  gas.  Wherever  it  meets  with  oxygen 
gas,  either  alone,  or  in  mixture  with  other  gases,  it  produces  deep 
brownish  red  fumes  of  nitrous  acid. 

This  property  need  be  indicated  here,  only  in  a  general  way,  be- 
because  it  will  be  more  fully  stated  under  the  nitrous  acid. 

1 .  Fill  a  tall  glass  tube  with  infusion  of  litmus,  or  purple  cabbage'; 
pass  up  some  bubbles  of  nitric  oxide  gas,  that  have  stood  for  an  hour 
or  two  over  water ;  there  will  be  no  alteration  in  the   color  of  the 
litmus ;  now  add  some  oxygen  gas,  or  common  air ;  there  will  still 
be  no  change  till  the  bubbles  reach  the  nitric  oxide  ;  then  red  fumes 
will  be  produced,  which  will  promptly  change  the  color  of  the  liquid 
to  red,  and  the  water  will  rise  rapidly,  on  account  of  the  absorption 
of  the  acid  vapor. 

2.  The  above  experiment  may  be  repeated,  only  using  a  tall  air 
jar,  and  common  air.     The  observer  who  sees  the  result  for  the  first 


*  As  I  once  experienced,  having  breathed  some  of  it,  for  nitrous  oxide,  from  an 
air  vessel.  Insects  that  will  live  in  some  of  the  other  noxious  gases  die  in  this,  and 
fishes  die  in  water  impregnated  with  it. — Murray. 

t  Murray.  Most  authors  say  brilliantly,  but  in  numerous  trials,  I  could  never 
make  it  burn  at  all.  It  will  never  answer  for  a  class  experiment.  May  it  not  be 
that  nitric  oxide  gas  has  been  in  this  case  confounded  with  nitrous  acid  vapor,  which 
is  more  energetic  in  supporting  combustion  ?  t  Henry. 


450  NITROUS  ACIDS. 

time,  is  astonished  at  the  deep  blood  red  color  of  the  fumes,  and 
the  rapid  absorption,  especially  when  oxygen  gas  is  employed.  In 
this  case,  the  hand  laid  upon  the  jar,  in  which  the  combination  is 
going  on,  is  sensible  of  considerable  heat. 

3.  Lift  out  of  the  pneumatic  cistern,  a  large  air  jar,  filled  with  ni- 
tric oxide  gas,  having  previously  slipped  under  it  a  pane  of  window 
glass ;  reverse  its  position,  and  suddenly  remove  the  glass  plate ;  im- 
mediately a  dense  cloud  of  red  nitrous  acid  vapor  will  rise  from  the 
mouth  of  the  jar,  and  the  hand  placed  in  the  current,  will  be  warm- 
ed. The  acid  will  soon  disappear,  being  absorbed  by  the  watery 
vapor  in  the  atmosphere. 

NITROUS    ACIDS. 

1.  General  Explanation. — It  is  obvious,  from  the  statements  that 
have  been  made,  that  whenever  nitric  oxide  gas  is  mingled  with  free 
oxygen  gas,  nitrous  acid  is  produced,  and  thus  these  gases  become 
very  delicate  tests  of  the  presence  of  each  other.  It  is  also  true, 
that  nitric  oxide  willl  sometimes  detach  oxygen  gas  from  combina- 
tion, and  form  with  it  nitrous  acid. 

(a.)  Prepare  a  flask  with  a  tube  bent  twice  at  right  angles,  thus  : 
in  the  flask  A,  place  the  copper  and  diluted  ni- 
tric acid  :  in  the  bottle  B,  some  pale  colorless 
nitric  acid.  As  soon  as  the  nitric  oxide  gas  be- 
gins to  be  evolved,  the  pale  acid  will  change  its 
color,  and  pass  rapidly  through  many  shades  of 
yellow,  ending  with  deep  green,  while  blood  red 
fumes  will  rise  from  the  surface.  These  chang- 
es are  owing  to  the  absorption  of  the  nitric  ox- 
ide gas,  by  the  nitric  acid  ;  this  is  at  the  same 
time  partially  decomposed,  giving  oxygen  to 
the  nitric  oxide  gas,  which  is  thus  converted  into  nitrous  acid,  and  in 
this  state  mingles  with  the  still  undecomposed  nitric  acid,  and  thus 
presents  a  variety  of  shades  of  color  ;*  "  even  a  little  more  than  1 
per  cent,  being  sufficient  to  impart  a  pale  yellow  color." 

(b.)  In  the  process  for  nitric  acid  from  the  nitrate  of  potash  and 
sulphuric  acid,  as  already  described,  p.  447  it  is  now  obvious  that  the 
red  fumes  which  appear  slightly  at  the  beginning,  and  abundantly  at 
the  end  of  the  distillation,  are  owing  to  the  decomposition  of  a  por- 
tion of  nitric  acid,  giving  both  nitric  oxide,  and  oxygen  gas,  which 
again  unite  in  different  proportions  from  the  original  ones,  and  thus 
produce  fuming  nitrous  acid. 

*  Heat,  gradually  and  long  applied,  will  discharge  this  color,  and  dilution  with 
water  does  it  instantly,  while  red  fumes  are  emitted. 


HYPO-NITROUS  ACID.  457 

In  the  middle  of  the  process,  when  the  first  effects  of  the  sulphu- 
ric acid  are  over,  and  the  materials  have  not  as  yet  become  very  hot, 
the  nitric  acid  passes,  without  decomposition,  and  by  changing 
the  receiver,  we  obtain  it  nearly  colorless.  If  any  combustible  is 
mixed  with  the  materials,  the  red  fumes  are  much  increased,  as  the 
acid  is  then  decomposed  more  rapidly  than  before. 

(c.)  In  all  cases  where  nitric  acid  acts  on  combustibles,  or  on 
metals,  it  becomes  colored,  and  emits  red  fumes,  especially  if  in  con- 
tact with  the  atmosphere  ;  this  is  owing  to  the  generation  of  nitrous 
acid,  in  consequence  of  the  extrication  of  nitric  oxide  gas,  and  its 
subsequent  reoxigenation  to  produce  nitrous  acid. 

(d.)  It  follows,  that  nearly  all  the  acids  of  the  nitric  family, 
found  in  the  shops,  and  in  the  arts,  and  all  that  are  colored,  are 
mixtures  of  nitric  and  nitrous  acids  ;  but  the  nitric  acid  usually  pre- 
vails, and  such  acids  by  uniting  with  bases,  form  true  nitrates ;  still  it 
is  true  that  the  purest  and  strongest  nitric  acid,  and  the  purest  and 
strongest  nitrous  acid  are  scarcely  known,  except  in  the  hands  of  the 
philosophical  chemist ;  the  pale  acid  of  the  shops  is  usually  a  nitric 
acid,  diluted,  more  or  less,  with  water ;  and  all  the  colored  acids, 
may,  by  additional  dilution,  or  by  the  proper  application  of  heat,  be 
brought  to  the  condition  of  nitric  acid. 

(e.)  Still,  although  there  are  many  varieties  in  the  weight,  color, 
fuming  properties,  and  energy  of  the  nitrous  acids  of  the  arts,  we 
must  not  suppose  that  there  is  a  great  diversity  of  real  nitrous  acids, 
and  that  the  nitric  oxide  and  oxygen  "  can  unite  in  every  propor- 
tion" within  certain  limits.  "  The  true  explanation  is,  that  the 
mixture  of  these  gases  may  give  rise  to  three  compounds,  the  hyponi- 
trous,  the  nitrous,  and  the  nitric  acids,  and  that  if  certain  precautions 
are  adopted,  either  of  them  may  be  formed,  almost  if  not  entire- 
ly, to  the  exclusion  of  the  others."* 

HYPO-NITROUS    ACID. 

1.  NAME  AND  HISTORY. — Called  by  some  per-nitrous,  but  hypo- 
or  sub-nitrous  seems  the  most  proper  name,  since  it  is  less  energetic 
as  an  acid  than  the  nitrous  and  nitric,  and  also  contains  less  oxygen. 
First  obtained  by  Mr.  Dalton,f  and  Gay-Lussac.f 

2.  PROCESS. 

(a.)  Mingle  over  mercury,  in  a  glass  tube,  containing  a  strong  so- 
lution of  pure  potassa,  400  measures  of  nitric  oxide  gas,  with  100 
of  oxygen.  The  compound  thus  formed,  will  be  absorbed  by  the 
alkali,  and  is  supposed  to  be  the  hypo-nitrous  acid. 

(6.)  If  100  measures  of  nitric  oxide  gas  be  exposed  for  three 
months  to  a  solution  of  pure  potassa,  over  mercury,  25  measures  of 

*  Turner. 

t  Thomson's  Ann.  Vol.  X.  *  Ann.  de  Chim.  et  de  Phys.  Vol.  I,  p.  400. 

58 


458  HYPO-NITROUS  ACID. 

nitrous  oxide  (protoxide)  will  be  left,  the  remainder  having  com- 
bined with  the  alkali  in  the  form  of  hypo-nitrous  acid,  oxygen  having 
been  afforded  by  one  portion  of  the  nitric  oxide,  which  was  thus  re- 
duced to  nitrous  oxide,  while  the  other,  by  the  aid  of  the  oxygen, 
became  nitrous  acid. 

(c.)  Gay-Lussac  supposes  that  he  obtained  the  same  acid  by  dis- 
tilling the  nitrate  of  lead,  the  volatile  product  being  condensed  in  a 
receiver,  kept  cold  by  a  freezing  mixture.*  But  it  is  perhaps,  not 
certain  that  the  hypo-nitrons  acid  has  yet  been  obtained  in  a  state  of 
freedom. 

3.  PROPERTIES. 

(a.)  The  acid  obtained  by  Gay-Lussac,  from  the  destructive  dis- 
tillation of  nitrate  of  lead,  boiled  at  79°  Fahr.  and  was  dissipated  in 
very  dense  red  fumes. 

(6.)  Poured  into  water,  nitric  oxide  gas  ivas  abundantly  liberated^ 
"  and  the  water  became  blue,  green,  and  yellow,  according  to  the 
proportion  added." 

(c.)  Sulphuric  acid,  either  strong,  or  a  little  weakened,  and  at  a 
moderate  temperature,  forms  with  the  hypo-nitrous  acid,  four  sided 
prisms,  which,  as  well  as  the  fluid  in  which  they  are  produced,  emit 
nitric  oxide  gas  by  the  contact  of  water. 

(d.)  Nitrous  acid  vapor,  passed  into  sulphuric  acid  gives  also  a 
similar  compound.-^ 

4.  CONSTITUTION. — Hypo-nitrons   acid  appears   to   consist,   by 
measure,  of  200  of  nitrogen  to  300  of  oxygen,  or  of  100  to  150  ; 
for  since  100  measures  of  oxygen  (see  2,)  are  mingled  with  400  of 
nitric  oxide  to  produce  hypo-nitrous  acid,  and  as  nitric  oxide  consists 
of  equal  volumes  of  nitrogen  and  oxygen,  it  follows  that  the  propor- 
tions are  as  above  stated.     Also,  in  the  experiment  2.  (b.)  "  deduct- 
ing from  the  nitrogen  and  oxygen  originally  contained  in  the  nitric 
oxide  gas,  the   quantities  constituting  25  of  nitrous  oxide,  we  shall 
find  that  25  volumes  of  nitrogen,  and  37.5  of  oxygen  had  disappear 
ed  and  formed  a  new  compound,  which  was  absorbed  by  the  potassa. 
Thus — 100  nitric  oxide  gas       =50  nitrogen  +50      oxygen, 

25  nitrous  oxide  gas    =25      "         -j-12.5     " 

25  37.5 

and  25  :  37.5  :    100  :  150."— H. 

These  are  exactly  the  proportions  assigned  by  Gay-Lussac  to  the 
hypo-nitrous  acid. 


*  Dulong  and  Dr.  Thomson,  however,  suppose  that  the  acid  obtained  in  this  case 
was  the  real  nitrous. — Murray. 

t  Also  by  mingling  oxygen  gas,  sulphurous  acid,  nitric  oxide  gas,  and  aqueous 
vapor,  a  similar  compound  is  produced.  Clement  and  Desormes,  its  discoverers, 
supposed  it  to  consist  of  sulphuric  acid  and  nitric  oxide  gas. — H. 


NITROUS  ACID.  459 

The  representative  number  of  hypo-nitrous  acid  is  38,  made  up 
of  1  proportion  of  nitrogen,  14,  and  3  of  oxygen,  24  ;  thus  answer- 
ing to  1  volume  of  nitrogen,  and  l£  of  oxygen — 1  volume  of  oxygen 
representing  two  proportions,  viz.  16. 

5.  The  hypo-nitrous  acid  cannot  be  obtained  from  its  alkaline 
combinations  in  the  isolated  form,  for  whenever  a  stronger  acid  is 
added,  to  separate  it  from  the  alkali,  it  is  decomposed  into  nitrous 
acid,  and  nitric  oxide  gas. 

NITROUS  ACID. 

It  has  been  already  explained,  in  what  sense  this  term  has  been 
generally  used  by  chemists.  It  now  appears  that  there  is  a  distinct 
and  peculiar  acid,  to  which  the  term  may  be  properly  applied. 

1.  PREPARATION. 

(a.)  According  to  Dr.  Thomson* — the  distillation  of  dry  nitrate 
of  lead  into  a  receiver  kept  cold  by  a  mixture  of  snow  and  salt,  affords 
this  acid  in  purity  ;  Gay-Lussac  considers  it  as  the  hypo-nitrous.f 

(b.)  Sir  Humphry  Davy  obtained  it  by  mixing  in  a  vessel  deprived 
of  air,  2  volumes  of  nitric  oxide  and  1  of  oxygen,  the  gases  being  both 
dry.  The  condensation,  according  to  Davy,  is  into  one  half;  ac- 
cording to  Gay-Lussac  and  Dr.  Thomson,  into  one  third  of  their 
original  volume. 

(c.)  The  correct  performance  of  this  experiment  requires  a  glass 
globe  adapted  to  the  air  pump,  and  also  to  glass  jars  from  which 
the  two  gases  can  be  introduced  in  their  proper  proportions. 

(d.)  The  common  class  experiment  of  mingling  the  gases  by  pour- 
ing them  into  glass  jars  through  water,  in  the  pneumatic  cistern,  gives 
a  mixed  acid  ;  composed  probably  of  the  three  varieties — nitric,  ni- 
trous, and  hypo-nitrous. 

2.  PROPERTIES. 

(a.)  In  dry  glass  vessels,  it  forms  a  deep  blood  red  vapor,  or  per- 
haps it  might  be  called  a  gas. 

(b.)  It  is,  however,  condensed  into  a  liquid  by  a  low  temperature. 
The  density  of  the  anhydrous  acid  is  1.451. 

(c.)  We  have  the  authority  of  Dulong  and  of  Dr.  Thomson,  that 
the  red  fuming  acid  distilled  into  a  cold  receiver  from  nitrate  of  lead, 
is  really  anhydrous  nitrous  acid. 

(d.)  ItJ  is  very  corrosive — intensely  acid — odor  very  pungent, — 
color,  yellowish  orange — at  common  temperatures,  it  is  a  fuming  li- 
quid, but  evaporates  rapidly  and  boils  at  82°§  Fahr.  The  exhala- 
tions are  the  common  nitrous  acid  vapors,  which,  when  once  mingled 
with  other  gases,  require  a  very  intense  cold  to  condense  them. 

*  Elements,  Vol.  I,  p.  120.  t  Ann.  de  Chira.  et  de  Phys.  Vol.  I,  p.  405. 

i  It  will  be  observed  that  this  description  applies  also  to  what  Gay-Lussac  consid- 
ered as  hypo-nitrous  acid ;  see  his  memoir,  Ann.  de  Chim.  etde  Phys.  T.  I,  p.  405. 

§  Berzelius  remarks  that  nitrous  acid  of  the  same  density  with  nitric  that  boils  at 
236°,  boils  at  160°. 


460  NITROUS  ACID. 

(e.)  Action  of  water.  To  form  liquid  nitrous  acid,  nothing  more 
is  necessary  than  to  add  this  vapor  to  water — mixed  with  a  large 
quantity  of  this  fluid,  it  becomes  nitric  acid,  which  remains  colorless 
in  the  water,  while  a  quantity  of  nitric  oxide  gas  escapes  into  the  air, 
producing  the  usual  red  fumes. 

But  if  the  nitrous  acid  is  added  to  a  very  little  water,  the  gas  is 
retained  and  the  fluid  becomes  green  ;  with  an  intermediate  quantity  of 
water,  the  anhydrous  nitrous  acid,  when  dropped  in,  emits  at  first,  a 
considerable  quantity  of  red  fumes,  which  however  diminish  as  more 
acid  is  added,  and  finally  cease. 

In  the  progress  of  the  addition  of  the  acid  to  the  water,  (as  has 
been  already  stated  under  the  hypo- nitrous  acid,)  the  liquid  passes 
through  shades  of  greenish  blue,  and  green  of  various  tints,  and  be- 
comes at  length,  orange  yellow,  which  is  the  color  of  the  acid  itself. 
These  changes  of  color  are  evidently  owing  to  a  mixture  of  differ- 
ent proportions  of  the  three  acids,  and  of  the  nitric  oxide.* 

(f.)  Action  on  animals;  highly  irritating  and  suffocating  in 
the  glottis ;  it  should  be  avoided  as  much  as  possible.  In  the  nu- 
merous experiments  of  the  laboratory,  in  which  nitrous  vapors  are  dis- 
engaged, it  sometimes  produces  permanent  injury,  and  often  a  dis- 
tressing stricture  of  the  chest,  with  a  continued  sense  of  pressure  and 
suffocation. 

(g.)  Action  on  combustibles.  A  candle  burns  in  this  vapor  with 
some  brilliancy,  and  phosphorus  burns  with  splendor — ignited  charcoal 
continues  to  burn,  but  with  a  dull  red  light. 

(h.)  By  calculation  from  the  weight  of  the  elements  and  their  con- 
densation, this  acid,  in  the  aerial  form,  must  iveigh  65.3  grains,  at 
a  medium  temperature  and  pressure.' 

(*".)  Action  on  colors. — It  is  scarcely  necessary  to  add  that  this 
acid  reddens  litmus  and  affects  the  other  test  colors,  as  the  acids  gen- 
erally do. 

(j.)  The  nitrous  acid  cannot  be  combined  directly  with  the  bases; 
it  affords  with  potassa,  for  instance,  nitrate  and  hypo-nitrite,  without 
any  proper  nitrite. f 

3.  Test  for  nitrous  acid. — We  owe  to  Gay-Lussac   the  know- 
ledge of  the  fact  that  the  red  sulphate  of  manganese  becomes  instantly 
colorless  by  the  action  of  the  nitrous  acids  ;  which,  by  detaching  oxy- 
gen, bring  it  to  the  state  of  wrhite  sulphate,  while  nitric  acid  has  no 
such  effect. 

4.  REPRESENTATIVE   NUMBER  AND  CONSTITUTION. — As  nitrous 
acid  is  formed  from  2  volumes  of  nitric  oxide,   consisting  of  equal 
volumes  of  oxygen  and  nitrogen,  with  the  addition  of  one  volume  of 


*  For  an  ingenious  theoretical  explanation,  more  in  detail,  see  Turner's  Elements, 
2d  Ed.  p.  225. 

t  Ann.  de  Chim.  et  de  Phya.  T.  I,  p.  410. 


NITROUS  ACIDS.  461 

oxygen,  it  consists  obviously  of  4  equivalents  of  oxygen  32,  and  1  of 
nitrogen  14,  which  make  the  number  representing  it,  46. 

5.  USES. — Most  of  the  acids  of  this  class  used  in  chemistry  and  the 
arts,  and  even  in  medicine,  are,  as  already  stated,  rather  nitrous  than 
nitric  acids,  or  rather  mixtures  of  the  two  or  even  three  varieties.* 

In  medicine,  this  fact  is  of  no  moment,  because  the  acid  is  always 
given  largely  diluted  with  water,  and  in  this  state,  it  is  a  weak  nitric 
acid  ;  and  indeed,  in  most  of  the  arts,  it  is  used  in  a  state  of  dilution. 
For  the  purposes  of  oxidation  and  combustion,  the  nitrous  acids  are 
used  indiscriminately  with  the  nitric ;  and  the  highly  fuming  acids,  if 
equally  concentrated,  are  thought  to  be  even  better  for  some  brilliant 
experiments,  such  as  the  combustion  of  oils,  of  charcoal  and  of  phos- 
phorus. In  chemical  analysis,  the  nitric  acid  is  generally  employed  ; 
the  nitrous  is  resorted  to  only  occasionally. 

APPENDIX  TO  THE  HISTORY  OF  THE  NITROUS  ACIDS. 

1 .  Application  of  nitric  oxide  gas. — It  is  obvious,  from  the  pre- 
ceding statements,  that  nitric  oxide  gas  and  oxygen  gas,  are  mutu- 
ally tests.     To  know  whether  there  is  in  any  gas  a  mixture  of  free 
oxygen  or  of  common  air,  it  is  necessary  only  to  add  a  little  nitric  ox- 
ide, when,  if  there  is  any  uncombined  oxygen  gas  present,  the  red 
fumes  will  appear.     So  far  as  this  fact  goes,  the  nitric  oxide  is  an  im- 
portant agent  in  the  hands  of  the  chemist,  but,  as  regards  the  amount  of 
oxygen  present,  there  has  been  much  diversity  in  the  results  obtained 
in  different  modes  of  operating.     As  the  causes  of  this  diversity  could 
not  be  fully  understood  until  we  had  become  acquainted  with  the  ni- 
trous acids,  this  subject  has  been  reserved  for  the  present  place. 

2.  Common  air.    When,  in  a  glass  receiver  over  ivater,  nitric  oxide 

fas  is  mixed  with  common  air,  the  red  fumes  appear,  and  by  ming- 
ng  them  in  proper  proportions  and  in  a  proper  manner,  the  ivhole  of 
the  oxygen  will  be  withdrawn,  and  the  nitrogen  will  be  left — the  ni- 
trous acid  being  absorbed  by  the  water. 

3.  Oxygen  gas. — In  the  same  manner,  oxygen  gas  ivill  be  absorb- 
ed only  with  more  energy,  and  it  can  be  known  in  either  case,  which 
gas  is  in   excess,  by  adding  cautiously  and  in  small  quantities,  either 
oxygen  gas  or  nitric  oxide  ;  if  there  is  a  residuum  of  either  gas,  there 
will  be  red  fumes,  on  adding  the  other.     If  pure  oxygen  gas  is  em- 
ployed, and  pure  nitric  oxide,  in  proper  proportions  over  water,  the 
absorption  will  be   entire,  and   either  gas,  by  adding  the  other,  can 
be  completely  withdrawn  from  any  mixture  of  gases. 

*  They  are  generally,  described  as  nitric  acid,  holding  in  solution  variable  quan- 
tifies of  nitric  oxide  gas ;  but  the  more  correct  view  appears  to  be  that  in  the  text 
(and  on  p.  457  d.)  I  have  always  found  that  the  fumes  obtained  by  heating  or  dilu- 
ting the  colored  and  fuming  acids,  are  still  more  red  and  fuming,  and  indeed,  it  seems 
impossible  that  nitric  oxide  gas,  should  be  in  contact  with  nitric  acid,  without  de- 
composing it,  and  taking  enough  of  its  oxygen,  both  to  form  and  to  leave  nitrous  acid, 
and  the  same  effect  will  of  course  be  produced  by  any  combustible  body. 


462  NITROUS  ACIDS. 

4.  Apparent  caprice. 

(a.)  It  has  been  found,  however,  that  the  amount  of  oxygen  ab- 
sorbed, is  very  different  in  different  cases,  and  that  it  is  influenced  by 
the  proportion  in  which  the  gases  are  mixed — the  time  that  elapses 
after  they  are  mixed — the  size  and  form  of  the  vessels — the  greater 
or  smaller  surface  of  the  water  over  which,  and  the  rapidity  with 
which,  the  mixture  is  made ;  and  perhaps  by  other  causes,  such  as 
agitation,  temperature  and  order  of  mixture. 

(b.)  According  to  Davy,  when  large  quantities  of  nitric  oxide  gas 
are  added  to  small  quantities  of  oxygen  in  vessels  of  large  diameter, 
the  absorption  is  from  2  to  3  of  nitric  oxide  for  1  of  oxygen — but  if 
large  quantities  of  oxygen  are  added  to  small  quantities  of  nitric  ox- 
ide gas  in  narrow  tubes,  the  absorption  is  from  1  to  1.5  of  oxygen  in 
volume,  and  2  of  the  nitric  oxide  gas. 

(c.)  Surface  of  water. — In  general,  the  larger  the  surface  of  the 
water,  the  more  rapid  the  absorption — and  therefore  for  want  of  time, 
less  oxygen  is  combined  ;  in  such  case,  more  of  the  nitrous  and  less 
of  the  nitric  acid  will  be  formed. 

(d.)  Cause  of  the  variable  absorption. — Dr.  Priestley,  supposing 
that  the  nitric  oxide  and  oxygen  combined  in  only  one  proportion, 
very  early  employed  them  in  eudiometry — but  he  was  ignorant  of  the 
fact  that  they  combine  in  three  proportions  ;  producing  hypo-nitrous, 
nitrous  and  nitric  acids,  and  that  it  is  the  varying  production  of  one 
or  another  of  these,  and  in  different  proportions,  that  creates  the  ap- 
parent caprice. 

(e.)  Can  the  uncertainty  be  removed  ? — Dr.  Henry,  in  his  Ele- 
ments— Mr.  Dalton,  in  the  10th  Vol.  of  the  Annals  of  Philosophy, 
and  Gay-Lussac,  in  the  2d  Vol.  p.  247,  of  the  Memoires  d'Arceuil, 
have  given  minute  directions  how  this  may  be  with  more  or  less 
certainty  effected. 

(/.)  The  process  of  Gay-Lussac,  resembling  the  original  one  of 
Dr.  Priestley,  is  worthy  of  being  mentioned. 

In  a  wide  jar,  a  common  tumbler  glass,  or  a  tube  not  less  than  1 J 
inch  in  diameter,*  add  100  measures  of  nitric  oxide,  to  100  of  com- 
mon air ;  the  absorption  will  be  complete  in  half  a  minute  or  a  min- 
ute ;  the  residue  being  measured  in  a  graduated  tube,  will  indicate  a 
diminution  of  84  measures  out  of  the  200 ;  one  fourthf  of  the  di- 
minution is  oxygen,  =21,  and  84—21  =  63,  the  proportion  of  nitric 
oxide  gas  that  has  been  acidified. 

In  applying  this  process  to  mixed  gases,  containing  sometimes  more 
and  sometimes  less  than  the  oxygen  in  the  air,  the  result  was  found 
to  be  correct.  When  the  proportion  of  oxygen  was  greater  than  in 


*  Murray. 

t  The  division  by  four  seems  to  be  founded  on  experience  only,  as  no  reason  ap- 
pears why  that  number  should  give  in  this  case  a  uniform  result. 


NITROUS  ACIDS.  453 

the  air,  the  quantity  of  nitric  oxide  should  of  course  be  increased,  that 
it  may  be  present  in  excess. 

(g.)  The  processs  of  Davy. — Nitric  oxide  gas  being  largely  and 
readily  absorbable  by  the  green  sulphate,  and  the  green  muriate 
(proto,)  of  iron,  in  that  condition  will  attract  powerfully  the  oxygen 
of  the  air. 

The  nitric  oxide  which  is  to  be  used,  should  be  previously  agita- 
ted in  a  tube,  with  one  of  these  solutions,  in  order  to  determine 
whether  there  is  nitrogen  mixed  with  it.  A  strong  watery  solu- 
tion of  one  of  the  salts  just  named,  the  acid  being  also  saturated  with 
the  oxide  of  iron,  is  next  to  be  fully  impregnated  with  the  ni- 
tric oxide ;  it  should  be  kept  in  small  divided  portions  in  close  vials, 
and  applied  as  it  is  wanted,  in  Dr.  Hope's  Eudiometer,  or  in  some 
other  adequate  instrument. 

The  protosulphate  of  iron  is  preferred,  but  the  solution  is  liable  to 
spontaneous  decomposition,  the  protoxide  of  iron  attracting  oxygen, 
both  from  the  water  and  the  nitric  oxide,  and  the  nitrogen  of  the  lat- 
ter, combining  with  the  hydrogen  of  the  former,  ammonia  is  gener- 
ated. Gas  is  said  also  to  be  emitted. — See  Davy's  researches. 

Dr.  Hare  remarks,  "  as  nitric  oxide  consists  of  a  volume  of  nitro- 
gen and  a  volume  of  oxygen  uncondensed,  to  convert  it  into  nitrous 
acid  which  consists  of  a  volume  of  nitrogen,  and  two  volumes  of  ox- 
ygen, would  require  one  volume  of  oxygen.  Of  course,  if  nitrous 
acid  be  the  product,  one  third  of  the  deficit  produced,  would  be 
the  quantity  of  atomspheric  oxygen  present.  This  would  be  too 
much  to  correspond  with  the  formula  of  Gay-Lussac." 

"  Supposing  hyponitrous  acid  produced,  only  half  as  much  oxygen 
would  be  required,  as  is  necessary  to  produce  nitrous  acid  ;  so  that 
instead  of  the  two  volumes  of  nitric  oxide  taking  one  volume,  they 
would  take  only  a  half  volume.  The  ratio  of  J  in  2.j,  is  the  same 
as  1  in  5,  or  one  fifth,  which  is  too  little  for  Gay-Lussac's  rule." 

"  The  formula  recommended  by  Dr.  Thomson,  agreeably  to  which, 
J  of  the  deficit  is  to  be  ascribed  to  oxygen  gas,  is  perfectly  consist- 
ent with  the  theory  of  volumes,  and  much  more  consonant  with  the 
results  of  my  experiments,  than  that  recommended  by  the  celebrated 
author  of  that  admirable  theory."* 

*  "  The  late  Professor  Dana  ingeniously  reconciled  Gay-Lussac's  statement,  with 
the  theory  of  volumes,  by  suggesting  that  a  half  volume  of  oxygen  may  take  one 
volume  of  the  nitric  oxide,  and  another  half  volume  of  oxygen,  two  volumes. 
Vol.  Vol. 

£  oxygen  takes  1  oxide  and  forms  nitrous  acid. 

&  oxygen  2  oxide  and  forms  hyponitrous  acid. 

Deficit  due  to  oxygen  is  as  1  to  3 

This  result  is  evidently  dependent  upon  the  contingencies,  which  may  prevent 
nitrous  acid  from  being  the  predominant  product." 


464  NITRATES. 

Antiseptic  properties  of  nitric  oxide. — Nitric  oxide  is  thought  to 
be  an  antiseptic.  Dr.  Priestly  says  that  it  renders  bladders  in  which 
it  has  been  kept  imputresible. 

He  tried  many  experiments  on  the  preservation  of  meats  by  this 
gas.  It  generally  saved  them  from  putrefaction,  and  even  stopped 
the  progress  of  putrefaction  already  begun,  but  meats  preserved  in  it 
had  always  a  bad  taste. 

NITRATES  OF  ALKALIES. 

A  highly  important  and  interesting  class  of  salts ;  the  principal  ni- 
trate, that  of  potash,  having  been  known  from  remote  antiquity. 

GENERAL    CHARACTERS. 

1.  Soluble,  and  crystallizable  by  the  cooling  of  the  hot  solution. 

2.  At  a  red  heat,  detonating  with  combustibles. 

3.  Decomposed  by  sulphuric  acid,  nitric  or  nitrous  acid  being 
evolved. 

4.  Producing  chlorine  and  dissolving  gold  leaf,  when  decomposed 
by  muriatic  acid. 

5.  Totally  decomposed  by  heat,  and  (nitrate  of  ammonia  except- 
ed,)  affording  oxygen,  mixed  more  or  less  with  other  gases. 

NITRATE  OF  POTASSA. 

1.  SYNONYMES. 

Nitre — salt  petre. — The  nitre  of  the  scriptures  is  carbonate  of 
soda.* 

2.  HISTORY. — Known  to  the  Romans;  to  the  Chinese,  from  re- 
mote antiquity,  and  to  the  earliest  chemists. 

(b.)  Roger  Bacon,  in  the  thirteenth  century,  mentions  it  under 
the  name  of  nitre.  Although  the  subject  of  experiments  for  many 
centuries,  Hooke  and  Mayhow,  in  the  17th  century,  having  come 
very  near  discovering  its  real  character,  and  Hales,  in  the  beginning 
of  the  18th,  having  extracted  from  it  by  heat,  a  great  quantity  of  gas, 
its  nature  was  not  understood  till  the  era  of  the  modern  chemistry. 

3.  PREPARATION. — By  saturating  pure  nitric  acid  with  potassa, 
or  its  carbonate,  and  then  evaporating  and  crystallizing.     But  it  is 
not  necessary  to  prepare  it,  as  it  is  found  abundantly  in  commerce, 
and  sufficiently  pure  for  most  purposes  in  chemistry. 

4.  PHYSICAL  PROPERTIES. 

(a.)  The  most  common  form  of  the  crystals  is  that  of  the  six 
sided  prism,  with  a  wedge-shaped  termination. 

*  The  word  nitre  is  mentioned  only  twice  in  the  sacred  writings,  viz.  Prov.  xxv, 
20.  and  Jeremiah,  ii,  22.  It  has  been  already  mentioned  (p.  251,  Soda,)  that  in  the 
first  intsance,  allusion  is  made  to  an  effervescence  produced  by  an  acid,  and  in  the 
second  to  a  detergent,  or  cleansing  property ;  neither  of  which  belong  to  nitrate 
of  potash,  but  both  of  them  to  the  carbonate  of  soda — the  natron  of  the  Greeks — 
the  nitrum  of  the  Latins.  With  this  understanding,  the  allusions  are  appropriate 
and  beautiful ;  otherwise  unmeaning ;  and  this  use  is  sustained  by  Pliny,  and  other 
ancient  authors.  The  carbonate  of  soda  is  used  largely  in  Great  Britain  in  washing. 


NITRE.  465 

(b.)  More  commonly,  however,  it  is  in  crystalline,  striated  or 
channeled  masses,  which,  when  of  considerable  length,  are  called 
stick  nitre. 

Sc.)  Primitive  form,  a  right  rhombic  prism — incidence  of  the  lat- 
planes,  109.50;  ratio  between  one  side  of  the  base  and  the 
height,  nearly  :  1  :  0.48. 

Cleavage,  "  parallel  to  all  the  faces  of  the  primitive,  and  also  to  a 
plane  passing  through  the  two  short  diagonals  of  the  bases.* 

Nitre  sometimes  crystallizes  in  tables,  or  laminae,  and  in  the  prism 
of  six  sides,  the  two  opposite  ones  are  commonly  broad ;  the  prism 
is  sometimes  terminated  by  18  faces  at  each  extremity,  arranged  in 
three  rows,  each  having  six  faces,  "  as  if  three  truncated  pyramids 
were  piled  on  each  other."  Sp.  gr.  1 .9603. 

(d.)  Taste,  bitterish  and  cool. 

(e.)  Brittle,  and  easily  pulverized. 

CHIEF  CHEMICAL  PROPERTIES. 

1.  ACTION    OF  HEAT. — This  salt  is  anhydrous,  and  the    small 
portion  of  water  that  is  lodged  mechanically  between  the  plates  of 
the  crystals  is  easily  dissipated  by  low  ignition. 

(a.)  It  melts  quietly  into  an  oil-like  liquid,  and  if  cooled,  congeals 
into  a  smooth  white  mass.f 

(b.)  If  the  heat  be  increased  to  redness,  we  obtain  oxygen  gas,  to  the 
amount  of  about  J  of  the  weight  of  the  nitre  employed.  The  first 
portions  are  pure,  but  after  about  }  part  has  been  withdrawn,  it  is 
obtained  more  or  less  mixed  with  nitric  oxide  gas,  and  with  nitrogen, 
which  prevail  most  towards  the  end. 

(c.)  If  the  heat  be  continued,  the  decomposition  is  entire,  and  po- 
tassa  remains  behind.  If  the  salt  be  removed  from  thejire,  when  only 
a  part  of  the  oxygen  gas  has  made  its  escape,  it  is  found  reduced  to 
the  state  of  nitrite. 

This  is  an  easy  process  for  oxygen  gas,  and  answers  very  well, 
where  we  do  not  want  it  very  pure.  It  is  usually  saved,  when  it 
is  so  good  as  to  re-light  a  candle  just  blown  out,  but  having  a  red  wick. 

In  a  gun  barrel  or  iron  bottle,  the  salt  should  be  melted  at  the  up- 
per part  first,  and  then  the  remainder  by  degrees ;  otherwise  there 
is  danger  of  an  explosion.  One  pound  of  nitre  yields  about  1200 
cubic  inches  of  oxygen  gas. 

2.  ACTION  OF  WATER. 

(a.)  Soluble  in  7  parts  of  water  at  60°  Fahr.  and  in  nearly  its  own 
weight  of  boiling  water  ;{  crystallizes  on  cooling.  When  mixed  with 

*  Levy,  Quart.  Jour,  Vol.  XV,  284,  and  Henry. 

t  When  melted,  it  is  sometimes  poured  into  moulds,  and  sold  in  round  lumps  like 
bullets,  under  the  name  Sal  prunella.  In  this  state  it  is  preferred  by  jewellers,  for 
heightening  the  color  of  their  wares. — J.  G. 

\  According  to  Dr.  Hope,  it  is  soluble  in  4  or  5  times  its  weight  of  water  at  60. 

59 


466  NITRE. 

water  it  sinks  the  thermometer  19°  during  its  solution.  With  ice  it 
produces  a  still  greater  degree  of  cold.  It  is  used  in  hot  countries  for 
cooling  wine  ;  and  the  same  portion  of  salt  by  evaporating  and  crys- 
tallizing, may  be  used  again  and  again. 

3.  ACTION  ON  COMBUSTIBLES. —  The  phenomena  are  brilliant 
and  instructive. 

(a.)  Action  of  charcoal. — If  into  melted  nitre,  charcoal  powder  be 
thrown,  it  deflagrates ;  and  if  3  parts  of  nitre  be  employed  to  1  of 
charcoal,  the  action  is  very  energetic.* 

(b.)  The  product  of  the  detonation  of  charcoal  and  nitre  is  always 
carbonic  acid  gas,  mixed  with  nitric  oxide  and  nitrogen,  and  probably 
with  oxide  of  carbon,  and  carbonate  of  potassa  remains.  If  igni- 
ted charcoal  be  held  above  melted  nitre,  it  will  burn  with  increased 
brilliancy,  owing  to  the  disengagement  of  oxygen  gas. 

(c.)  Jlction  of  sulphur. — Thrown  into  a  red  hot  crucible,  in  the 
proportion  of  3  parts  of  nitre  to  1  of  sulphur,  the  latter  burns  away  very 
completely  and  rapidly ;  the  products  are  sulphuric  and  sulphurous 
acid,  sulphate  of  potassa,  nitrogen  and  nitric  oxide  gas;  the  theory 
is  obvious.  It  has  been  already  mentioned,  that  in  the  manufacture 
of  sulphuric  acid  a  small  quantity  of  nitre,  usually  about  \  or  {,  is 
added  to  the  sulphur,  and  it  was  known  only  that  the  sulphur  was 
thus  made  to  burn  in  such  a  manner  as  to  form  sulphuric  rather  than 
sulphurous  acid.  Now  it  is  known  that  the  sulphur  decomposes  the 
nitric  acid  of  the  nitre,  by  attracting  such  a  proportion  of  its  oxygen 
as  leaves  nitric  oxide,  which  is  displaced  by  the  sulphuric  acid.  The 
nitric  oxide  meeting  with  oxygen  in  the  air,  forms  red  nitrous  acid 
vapor ;  in  the  mean  time  the  greater  part  of  the  sulphur  has  become 
sulphurous  acid ;  the  floor  of  the  leaden  chamber  is  covered  with 
water  several  inches  in  depth ;  so  that  aqueous  vapor,  sulphurous 
acid  and  nitrous  acid,  are  present,  in  mixture.  When  the  two  latter 
are  mingled  in  a  dry  state,  there  is  no  decomposition,  but  with  the  aid 
of  water  the  nitrous  acid  transfers  oxygen  to  the  sulphurous  acid  and 
converts  it  into  the  sulphuric ;  it  thus  becomes  again  nitric  oxide ;  again 
attracts  oxygen  and  transfers  it  to  the  sulphurous  acid  ;  and  thus  it 
becomes  a  vehicle  for  oxygen  between  the  atmosphere  and  the  sul- 
phurous acid.  A  small  quantity  of  water  enables  the  sulphurous  acid 
and  the  nitrous  to  unite  and  form  a  crystalline  solid,  as  appears  when 
a  drop  of  water  is  admitted  into  a  globe  containing  the  two  agents  in 
a  dry  state ;  the  same  thing  is  supposed  to  happen  in  the  leaden 
chamber,  and  the  abundant  water  on  the  floor  decomposing  this  com- 

*  The  Alchemists  performed  this  deflagration,  in  a  series  of  tubulated  receivers, 
connected  with  each  other,  and  with  a  tubulated  retort,  into  which,  when  red  hot, 
they  projected  their  mixture  of  charcoal  and  nitre,  immediately  closing  the  aperture 
of  the  retort;  their  apparatus  often  blew  up,  but  it  sometimes  escaped,  and  they 
then  carefully  collected  the  liquid  condensed  in  the  receivers  ;  this  they  called 
clyssus  of  nitre,  and  imagined  that  it  possessed  the  most  wonderful  properties  in 
alchemy. 


NITRE.  467 

pound,  enables  the  nitrous  acid  to  oxygenize  the  sulphurous  and  form 
sulphuric,  while  the  nitric  oxide  is  again  evolved,  to  perform  the  same 
function  anew.*  At  Fahlun,  in  Sweden,  they  are  enabled  to  manu- 
facture sulphuric  acid  in  small  leaden  chambers,  by  placing  upon  the 
floor  flat  glass  vessels  containing  nitric  acid,  which  is  decomposed  by 
the  sulphurous  acid  gas,  thus  evolving  nitric  oxide  gas  and  answering 
the  purpose  of  nitre,  which  is  here  omitted.  This  mode  is  less  eco- 
nomical than  the  common  one,  but  it  produces  a  purer  acid,  contain- 
ing only  .  1  or  .2  of  foreign  matter,  consisting  entirely  of  sulphate  of 
lead,  while  the  common  acid  contains  .5  or  .6  of  foreign  bodies.f 

4.  GUNPOWDER,  &tc. 

(a.)  History. — First  known  to  the  Chinese  ;  neither  its  European 
discoverer  nor  the  period  of  the  discovery  is  exactly  ascertained ; 
attributed  to  Roger  Bacon  and  to  Swartz,  a  German,  in  1320.J 

(b.)  Composition. — Gunpowder  is  an  intimate  mixture  of  nitre, 
sulphur  and  charcoal;  the  proportions  vary  in  different  manufacto- 
ries, and  for  different  purposes ;  but  those  employed  in  the  Royal 
Mills  of  England,  are  75  nitre,  15  charcoal,  10  sulphur.^  These 
are  the  proportions  generally  employed  in  other  countries.  The 
nitre,  being  the  most  expensive  article,  is  sometimes  stinted ;  this  of 
course  injures  the  quality  of  the  powder.  Common  gunpowder  often 
contains  not  more  than  .50  of  nitre.  || 

(c.)  Process  in  the  Royal  Mills  of  England. — The  ingredients 
are  as  pure  as  possible.  The  nitre  is  carefully  purified.  Common 
salt,  uncombined  potassa  and  sulphate  of  magnesia,1F  are  the  most 
common  impurities,  and  cause  the  powder  to  deliquesce.  The 
charcoal  is  made  in  ignited  iron  cylinders,  and  the  sulphur  must  be 
free  from  acid.  The  ingredients  are  separately  pulverized ;  then 

*  Ann.  de  Chim.  Vol.  LIX,  and  Davy's  Elements,  Am.  ed.  p.  1. 

t  Berzelius,  Ann.  de  Chim.  et  de  Phys.  Tome  IX,  p.  162.  The  acid  made  near 
New  York,  contains  only  .1  or  .2  of  foreign  matter. — J.  T. 

$  Gunpowder  was  not  known  in  Europe  before  the  end  of  the  thirteenth  century, 
probably  not  before  1320 ;  it  was  well  known  in  the  middle  of  the  fourteenth  cen- 
tury, and  cannon  were  used  in  Germany  before  1372 ;  first  used  by  the  English  at 
the  battle  of  Agincourt,  A.  D.  1415.  See  Nicholson's  Journal,  8vo.  series. 

§  In  France  75.    nitre,  Sweden  75.  Poland  80.  Italy  76.5 

9.5  sulphur,  16.  12.  12.5 

15.5  charcoal,  9.  8.  12.5 

100.  100.  100.  101.5 

Dr.  Watson's  essays. 
At  present,  both  in  England  and  France,  7  JVitre.  Charcoal.  Sulphur. 

common  powder  contains  $  "       -     75  12£  12£ 

Shooting  powder  for  the  sportsman,  78  12  10 

Or, 76  15  9 

Powder  for  blasting  in  mines  and  quarries,  65  15  20 

M.  Bouchet's  patent  powder,  78  12£  9£ 

The  shooting  powder  is  glazed  by  the  mutual  friction  of  the  grains  in  a  barrel, 
revolving  on  an  axis ;  the  proportion  of  nitre  and  charcoal  is  large,  to  insure  its  quick 
action.— Gray's  Op.  Chem.  p.  495.  ||  Black,  Vol.  I,  p.  432.  IT  Id. 


468  NITRE. 

mixed,  moistened  and  pounded  in  mortars,  or  ground,  to  the  consist- 
ence of  a  thick  paste,  by  large  wheels  of  stone  or  cast  iron,  shod  with 
copper.  This  mass  is  granulated,  by  passing  it  through  a  series*  of 
parchment  or  wire  sieves,  turned  by  cranks  and  covered  by  a  heavy 
piece  of  wood,  usually  lignum  vitae,  whose  motion  and  pressure  force 
the  powder  through,  in  the  form  of  grains.  It  is  next  sifted,  and 
then  dried,  in  drawers  with  canvass  bottoms,  by  hot  cylinders  or 
stoves  of  iron  placed  on  one  side  of  the  apartment,  of  which  the 
shelves  occupy  the  other  three ;  or,  as  now  practised  in  some  manu- 
factories, by  steam,  or  by  warm  air  thrown  in  from  another  apartment. f 

Gunpowder,  although  frequently  injured  by  dampness,  can  be  pre- 
served a  long  time,  as  appears  from  the  fact  that,  in  1782,  "there 
were  discovered,  at  Purfleet,  (England,)  some  barrels  of  very  small 
grained  powder,  manufactured  by  Sir  Polycarpus  Wharton,  surveyor 
of  the  ordnance  in  Charles  the  second's  reign. "J 

(d.)  Theory  of  its  combustion. — Gunpowder  is  merely  a  mechan- 
ical mixture;  no  chemical  action  takes  place  between  its  ingredients 
at  common  temperatures.^  Jit  a  red  heat  the  oxygen  of  the  nitre 
acts  on  the  sulphur  and  carbon,  with  which  it  is  intimately  blended ; 
the  combustion  is  therefore  intensely  rapid  and  violent,  and  it  happens 
equally  in  a  vacuum,  in  a  mephitic  gas,  or  in  a  dry  cavity  under  water, 
and  quite  independently  of  air  or  of  any  foreign  aid.  The  sulphur 
produces  a  rapid  combustion,  the  charcoal  contributes  largely  to 
the  formation  of  gas,  and  a  good  gunpowrder  cannot  be  made  without 
both  these  combustibles.  The  power  is  produced  by  the  sudden 
formation  and  disengagement  of  a  vast  volume  of  gases,  greatly  ex- 
panded by  the  heat. 

Gunpowder •,  wet  and  crushed  in  the  manner  of  a  squib,  maybe 
safely  although  imperfectly  burned  in  a  gun  or  pistol  barrel,  and  the 
gases  may  be  caught  in  an  air  jar  filled  with  water. — They  are  prin- 
cipally carbonic  acid,  nitrogen  and  nitric  oxide  ;  sulphurous  acid  gas 
and  sulphuretted  hydrogen,  and  some  ammonia ;  perhaps  also  carbu- 
retted  hydrogen  and  oxide  of  carbon.  Sulphuric  acid  is  produced 
and  forms  sulphate  of  potassa,  which  with  some  sulphuret,  a  little 
carbonate  of  potassa  and  charcoal,  remains.  The  smell  of  sulphu- 
retted hydrogen  gas  is  perceived  in  fire  arms,  especially  when  in 
the  act  of  being  cleaned. 

(e.)  The  volume  of  gases  produced  from  gunpowder  is,  at  60°,  250 
times,  and  at  the  moment  of  discharge  1000  times,  greater  than  that 

*  Said  to  be,  in  the  Royal  Mills  of  England,  24  in  number. 

t  For  an  account  of  the  mode  of  making  gunpowder  in  France,  see  Thenard,  5th 
ed.  Vol  III,  p.  251. 

t  Gray's  Op.  Chem. 

§  See  Am.  Jour.  Vol.  XVII,  p.  132,  where  it  appears  that  it  may  sometimes  ex- 
plode in  consequence  of  the  heat  given  out  by  sudden  compression  of  air,  if  not  of 
its  own  ingredients. 


NITRE.  469 

of  the  powder.*  As  each  additional  volume  of  gas  exerts  a  force 
equal  to  that  of  the  atmosphere,  1000  X  15  =  15000  pounds  on  a 
square  inch,  which  will  project  a  bullet  with  a  force  of  2000  feet  in 
a  second,  j-  The  general  rule  for  powder  for  heavy  shot  is  one  third 
of  the  weight  of  the  shot,  for  lighter  artillery  one  fourth.  Count 
Rumford  found  that  18  grains  of  gunpowder  raised  a  weight  of  18000 
Ibs.  The  goodness  of  gunpowder  is  judged  of  by  the  force  with 
which  it  impels  projectiles ;  it  is  measured  in  an  instrument  called  an 
eprouvette.  A  rude  analysis  of  gunpowder  is  easily  effected  by  dis>- 
solving  the  nitre  by  water  and  then  subliming  the  sulphur  out  of  the 
charcoal.  J 

(f.)  Pulvis  fulminans  or  fulminating  powder. $—*It  is  made  of  3 
parts  of  nitre,  2  pearl  ashes  and  1  sulphur,  well  dried  and  thor- 
oughly mixed,  by  gentle  trituration  in  a  warm  mortar.  It  is  placed 
in  a  spoon  and  heated  by  a  candle  or  the  embers  till  it  gradually 
blackens  and  melts,  when  it  explodes,  with  a  sharp  and  loud  report. 
If  the  heat  is  raised  too  high  or  too  rapidly,  the  powder  is  decompo- 
sed and  does  not  explode. 

(g.)  Theory. — Similar  to  that  of  gunpowder,  but  the  explosion 
happens  only  when  all  the  mass  is  melted,  and  the  gases  are  disen- 
gaged instantaneously,  whereas  the  grains  of  gunpowder ||  burn  suc- 


*  Vide  Robbing'  Essay  on  Gunnery,  and  Nich.  Jour.  IV,  258.  t  Murray. 

t  For  an  accurate  method  by  Gay  Lussac,  see  Ann.  de  Ch.  et  de  Phys.  XVI,  434. 

§  This  powder  is  used  by  sportsmen  for  priming,  to  insure  the  discharge  of  their 
fowling  pieces.  For  this  purpose  it  is  slowly  melted  over  the  fire,  care  being  taken 
to  stir  it  frequently.  When  the  fusion  is  complete,  it  is  taken  off  and  stirred  until 
cool,  which  leaves  it  in  the  state  of  a  fine  powder.  It  must  be  kept  in  close  vessels, 
since  it  rapidly  attracts  moisture  from  the  atmosphere. 

||  Composition  formerly  used  for  firing  artillery  is  60  nitre,  40  sulphur  and  20 
gunpowder;  rammed  into  a  small  pasteboard  cylinder. 

Chinese  blue  lights  for  signals,  28  nitre,  7  sulphur,  2  arsenic,  &  apart  rice  flour, 
and  water  enough  to  knead  them  into  a  stiff  paste ;  the  water  and  flour  retard  the 
combustion ;  this  paste  is  rammed  into  little  earthen  pots  and  kept  in  pitched  cloths. 

Fire  balls  to  be  thrown  into  an  enemy's  camp,  40  nitre,  15  charcoal,  3 pitch  and 
a  little  sulphur. 

It  is  not  consistent  with  the  object  of  this  work  to  enter  into  the  details  of  pyro- 
techny,  which  may  be  found  in  many  works,  Gray's  Op.  Chemist ;  Cutbush,  in  Am. 
Jour.  Vol.  VIII.  p.  118,  &c.  The  following  may  be  taken  as  examples  of  prepa- 
rations for  rockets. 

Powder  for  rockets. 

Rockets  of  one  or  two  ounces — 8  parts  gunpowder,  1  fine  soft  charcoal. 

Somewhat  larger — 10  ounces  gunpowder,  3£  saltpetre,  3  charcoal. 

Of  five  or  six  ounces  weight — 37  ounces  gunpowder,  8  saltpetre,  2  sulphur,  6 
charcoal,  2  iron  filings. 

Ten  to  twelve  ounces  weight — 17  ounces  gunpowder,  4  saltpetre,  3£  sulphur, 
1  charcoal. 

One  pound  weight — 16  ounces  gunpowder,  1  sulphur,  3  charcoal. 

Four  to  seven  pounds  weight — 31  saltpetre,  4£  sulphur,  10  charcoal. 

Still  larger — 8  pounds  saltpetre,  1|  sulphur,  2|  charcoal. 

The  contents  of  a  Congreve  rocket,  analysed  by  Gay  Lussac,  were  in  the  propor- 
tion of  720  nitre,  16  charcoal  and  234  sulphur.  A  rocket  made  upon  this  result  had 
the  same  properties  with  the  English. 


470  NITRE. 

cessively,  although  rapidly.*  This  powder  has  little  effect  on  a  ball 
when  fired  in  a  gun. 

(A.)  Another pulvis  fulminans  has  been  recently  proposed,  consist- 
ing of  nitre  2  parts,  neutral  carbonate  of  potassa  2,  sulphur  1  and 
marine  salt  6,  all  finely  powdered.  It  explodes  with  great  energy. f 

(i.)  Phosphorus. — If  a  mixture  of  phosphorus  and  nitre  be  struck 
forcibly  with  a  hot  hammer,  a  violent  detonation  takes  place,  and  jets 
of  flaming  phosphorus  dart  out  laterally  with  danger  to  the  spectators. 
It  is  not  a  proper  experiment  before  a  class. 

(/.)  Hydrogen  gas. — If  a  stream  of  this  gas  be  passed,  by  a  bent 
tube,  through  melted  nitre,  the  salt  is  decomposed  with  detonation, 
and  water  formed ;  the  experiment  requires  caution. 

(k.)  Powder  of  fusion — 3  parts  nitre,  1  sulphur,  and  1  fine  saw 
dust,  thoroughly  mixed.  If  this  mixture  is  surrounded  by  a  rim  of 
sheet  copper,  and  set  on  fire,  the  copper  instantly  melts,  being  con- 
verted at  the  same  time  into  a  sulphuret. 

(/.)  White  flux — equal  parts  of  nitre  and  crude  wine  tartar,  mixed 
and  deflagrated  in  a  red  hot  crucible. 

(m.)  Black  flux — 1  part  nitre  and  2  tartar,  deflagrated  in  the  same 
manner ;  it  is  a  mixture  of  carbonate  of  potassa  and  charcoal. 

The  substances,  under  ;,  k,  and  Z,  (especially  the  last,)  are  em- 
ployed as  fluxes,  and  for  other  purposes  in  small  metallurgic  operations. 

5.  ACTION  OF  ACIDS. 

Decomposed  by  phosphoric  and  boracic  acids,  aided  by  heat. 
Muriatic  acid  with  heat,  evolves  nitrous  acid  and  chlorine,  a  mix- 
ture with  which  the  alchemists,  used  to  dissolve  gold.    (See  chlorine.) 
Sulphuric  acid. — The  action  of  this  acid  has  been  mentioned. 

6.  COMPOSITION. — The  equivalent  of  nitrate  of  potassa  is  102  ;  it 
being  an  anhydrous  salt,  is  composed  of  1   proportion  of  dry  nitric 
acid  54-f  1  proportion  of  potassa  48  =  102.     For  100  parts,  of  the 
acid  52,94 -f  alkali  47.06  =  100. 

In  full  detail,  its  constitution  is, 

Oxygen  5  proportions,  5x8=40+   1  prop,  nitrogen,  14  =  54 

Potassium   1    proportion,   40 -}-l  proportion  oxygen,  8        =48 

102 

Thus  we  see  how  in  a  complex  compound  the  numbers  expressing 
the  combining  powers  of  all  the  principles  are  united,  according  to 
an  admirable  law. 


*  Vide  Black's  Lectures,  1,  433,  note  32.  The  difference  is  seen  when  a  train  is 
fired  on  a  board  and  another  between  two  boards  with  weights  upon  them  :  the  ra- 
pidity of  the  combustion  is  greatly  increased  by  the  reaction  of  the  flame,  as  in  the 
chamber  of  a  gun.  I  Ferussac's  Bulletin,  Aout,  1828. 


9  NITRE.  471 

7.  SOURCES  OF  NITRATE  OF  POTASSA. 

(a.)  Tliere  are  some  soils  which  contain  so  much  of  it  that  they  are 
catted  saltpetre  grounds.  In  Italy  and  Spain,  and  in  the  latter  es- 
pecially, it  is  found,  even  in  the  dust  of  the  roads  ;  and  when  the 
crops  of  wheat  fail,  the  farmers  frequently  obtain  an  indemnity,  by 
lixiviating  the  soil  for  nitre.*  In  India,  in  China,  and  in  the  eastern 
parts  of  Persia,  saltpetre  earths  are  very  common,  and  the  salt  even 
effloresces  on  the  surface  ;  and  from  these  countries  a  great  part 
of  the  nitre  used  in  Great  Britain  and  America  is  brought.  It  is 
found  in  pasture  grounds,  near  Lima,  in  South  America,  and  in 
Podolia,  a  province  of  Poland,  in  little  hillocks,  being  the  ruins  of 
habitations,  in  a  plain  country,  formerly  populous. 

(b.)  Nitre  is  usually  found  in  places  where  there  has  been  an  accu- 
mulation of  animal  and  vegetable  matters,  or  an  abundance  of  animal 
effluvia,  having  free  communication  with  the  air,  and  with  alkalies  or 
lime  ;  as  in  the  ruins  of  old  houses,  in  the  earth  of  cellars,  and  sta- 
bles, and  in  pigeon  lofts,  in  which  places  it  often  effloresces,  pro- 
vided the  walls  be  of  lime,  and  in  general  in  low  situations,  which 
have  been  frequently  impregnated  with  animal  or  vegetable  fluids  in 
a  putrescent  state.  Nitre  is  produced  in  grounds  much  trodden  by 
cattle,  and  frequently  impregnated  with  their  excrements. — Ure.  In 
such  places  the  nitre  is  constantly  reproduced,  after  being  remov- 
ed, especially  if  the  place  have  a  northern  exposure.  In  France 
the  richest  part  of  the  vegetable  mould  is  often  found  to  contain  nitre,f 
and  in  this  country,  such  sources  were  resorted  to,  to  afford  nitre 
during  the  war  of  the  revolution.  The  earthy  floors  of  the  tobacco 
houses  were  found  to  be  particularly  rich  in  this  salt. 

(c.)  Nitre  is  also  found  in  marly  and  calcareous  grounds  ;  or  rather 
another  salt  is  found  in  such  places,  greatly  resembling  nitre,  and  into 
which  it  is  easily  con  verted.  J 

(d.)  In  the  calcareous  caverns  of  the  Western  and  South  Western 
States  of  the  United  States  of  America,  there  are  vast  resources  for 
manufacturing  nitre,  derived  from  the  nitrate  of  lime,  found  in  these 
caves.  It  is  changed  into  saltpetre  by  wood  ashes — one  bushel  of 
earth,  in  some  instances,  yielding  from  3  to  10  pounds  of  the  salt. 
In  Kentucky,  there  are  masses  of  ready  formed  nitre,  mixed  in  sand- 
stone rocks. 

(e.)  In  vegetables. — Nitre  is  found  in  borage,  bugloss,  parietaria, 
hemlock,  and  the  sunflower ;  and  in  the  dried  branches  of  this  last, 

*  Black,  Vol.  II,  p.  444. 

t  They  prefer  the  earths  that  are  at  a  little  distance  from  the  surface  of  the 
ground ;  they  are  distinguished  by  their  sharp  taste  ;  it  is  a  rich  nitre  ground  that 
contains  5  per  cent. 

t  The  wells  of  great  cities  also  afford  this  salt.  In  Peale's  Museum,  in  Philadel- 
phia, is  deposited  a  quantity  of  nitre,  obtained  along  with  other  salts,  during  the 
analysis  of  the  pump  water  of  that  city. 


472  NITRE. 

as  well  as  of  other  plants,  it  is  sometimes  found  crystallized  in  nee 
dies.     It  exists  in  tobacco  ;  and  sometimes  the  stalks  of  this  plant 
contain  so  much  nitre  that  when  dried,  they  will  burn  like  a  squib. 

The  nitre  in  plants  appears  to  be  derived  from  the  soil. 

How  is  nitre  formed  ? 

(/.)  During  the  decomposition  of  bodies  containing  nitrogen,  this 
principle  has  been  supposed  to  combine  with  the  oxygen  of  the  air,  to 
form  this  acid,  and  this  unites  with  any  proper  base. 

Lime  is  often  present,  and  forms  in  this  manner  nitrate  of  lime, 
which  by  a  substitution  of  the  alkali,  from  weeds,  ashes,  &c.  is  chang- 
ed into  nitrate  of  potassa. 

(g.)  There  seems  great  reason  to  believe  that  the  atmosphere  is,  to  a 
certain  extent,  converted  by  electrical  agencies,  into  nitric  acid,  as 
nothing  more  is  necessary,  than  that  the  elements  should  unite  in 
nearly  the  reversed  proportions  in  which  they  exist  in  the  air.  There 
is  a  popular  impression  that  thunder  and  lightning,  and  also  clear 
frosty  weather,  are  favorable  to  the  production  of  nitre.  That  its 
production  depends  upon  atmospherical  phenomena,  seems  to  be 
proved  from  the  fact,  that  the  lixiviated  saltpetre  earth  becomes  im- 
pregnated again  in  a  year  or  or  two,  by  exposure  to  the  air. 

(h.)  Jlrtificial  nitre  beds. — Most  of  the  nitre  used  on  the  continent 
of  Europe,  is  produced  from  composts,  formed  of  garden  mould,  lime 
rubbish,  ashes,  and  marly  earths,  and  animal  and  vegetable  sub- 
stances, of  every  description.  The  bed  is  screened  by  a  thatched 
roof,  through  which  the  air  has  access,  although  it  does  not  circulate 
very  freely.  The  heap  is  frequently  stirred,  and  moistened  from 
time  to  time  with  the  drainings  of  the  barn  yards,  and  of  the  kitchen. 
To  favor  the  process,  situations  are  sometimes  chosen  on  the  de- 
clivities of  hills.  Moderate  light,  moderate  moisture,  a  temperature 
from  65°  to  90°,  and  (as  asserted,)  additions  of  common  salt,  pro- 
mote the  production  of  nitre. 

8.  EXTRACTION. — The  nitrous  earths,  mixed  with  quick  lime  and 
ashes,  are  placed  in  large  vats  or  barrels,  with  perforated  bottoms,  cov- 
ered with  straw,  and  sometimes  there  is  a  second  bottom,  below  the 
first,  with  a  stop  cock  between.  Water  dissolves  the  nitrates,  the 
ashes  decompose  the  nitrates  of  lime  and  magnesia,  and  the  nitrates 
of  potash,  and  other  soluble  salts,  are  drawn  off  below.  In  the  re- 
fining of  nitre,  eggs,  milk,  soap,  and  twigs  of  euphorbia,  are  used. 
The  solution  is  then  concentrated  by  heat,  and  suffered  to  crystallize. 
It  is  at  first  a  dirty  mass  with  many  impurities,  particularly  common 
salt.  From  these  it  is  purified  by  successive  solutions,  evaporations, 
and  crystallizations.  The  earthy  bases  are  precipitated  by  potassa, 
or  ashes.  Such  salts  as  are  less  soluble  than  nitre,  are  separated 
during  the  evaporation,  and  such  as  are  more  soluble,  are  drawn  off 
with  the  mother  water.  These  operations  are  repeated  three  or  four 


NITRATE  OF  SODA.  473 

times  before  the  nitre  is  sufficiently  pure  for  the  manufacture  of  gun- 
powder. 

9.  USES. — Nitre*  is  an  important  substance.  It  is  nearly  indis- 
pensable in  the  manufacture  of  the  nitric  and  sulphuric  acids.  In 
medicine  it  is  given  as  .a  diuretic,  and  cooling  remedy ;  it  is  a  pow- 
erful antiseptic,  and  is  much  used  in  the  salting  of  beef,  to  the  fibre 
of  which  it  gives  a  fine  red  color,  and  great  firmness. f 

It  is  given  only  in  inflammatory  states  of  the  body,  5  to  20  grains 
at  a  time,  and  not  exceeding  1  or  lj  drachms  in  a  day ;  it  di- 
minishes heat  and  vascular  action,  and  is  cathartic. 

In  a  dose  of  an  ounce,  it  is  a  violent  poison,  and  has  often  been 
sold  and  given  by  mistake,  for  sulphate  of  soda.  It  can  always  be 
distinguished  by  throwing  it  on  burning  coals,  when  if  genuine,  it 
will  deflagrate  ;  and  by  the  emission  of  fumes  of  nitric  acid,  when 
sulphuric  acid  is  added  to  it. 

In  Chemistry,  it  affords  oxygen  gas ;  it  imparts  oxygen  to  many 
substances  which-  cannot  be  made  to  combine  with  it  in  any  other 
way,  as  to  metallic  titanium,  which  resists  even  nitro-muriatic  acid. 
It  is  employed  in  metallurgic  operations,  in  the  assaying  of  ores,  and 
it  is  used  to  determine,  by  deflagration,  the  proportion  of  carbonace- 
ous or  other  combustible  matter  contained  in  a  soil,  in  coal,  &c.  It 
has^changed  the  whole  art  of  war ;  and  in  naval  conflicts,  gunpowder 
is,  and  must  remain,  the  principal  means  of  annoyance. 

NITRATE  OF   SODA. 

1 .  NAME  AND  PREPARATION. — Formerly  called  cubic  nitre,  from  the 
obtuse  rhomboidal  form  of  its  crystals.     It  is  prepared  by  saturating 
soda,  or  its  carbonate,  with  nitric  acid;  it  is  not  known  in  the  shops. 

2.  PROPERTIES. 

(a.)  Taste  more  bitter  than  that  of  nitre,  but  its  general  proper- 
ties very  similar. 

J^.)  Rather  more  soluble,  requiring  only  3  parts  of  water  at  60°, 
less  than  its  own  weight  at  212°. 

(c.)  Effected  by  heat,  acids  and  combustibles,  in  the  same  manner 
as  nitre,  but  is  less  fusible. 

(d.)  Slightly  deliquescent,  and  therefore  unfit  for  making  gunpow- 
der. 

3.  COMPOSITION. — According  to  Dalton,  57.6  and  42.4  base,  but 
Dr.  Henry  remarks  that  these  numbers  do  not  agree  with  equivalent 
proportions.     On  the  authority  of  Wenzel,  quoted  by  Brande,{  it  is 

*  For  the  sake  of  brevity,  I  have  generally,  in  this  article,  used  the  word  nitre  in- 
stead of  nitrate  of  potassa. 

t  Muscular  fibre  after  being  thoroughly  impregnated  with  salt,  especially  with  the 
addition  of  nitre  and  dried,  becomes  nearly  imputrescible.  In  the  Leverian  museum, 
in  London,  I  saw  beef  in  1805^  a  remnant  of  the  provisions  with  which  Lord  Anson 
performed  his  circumnavigation,  from  1739  to  1744. 

\  Tables  of  definite  proportions. 

60 


474  NITRATE  OF  AMMONIA. 

composed  of  1  proportion  of  soda  32,  and  \  of  nitric  acid  54  =  86, 
its  equivalent. 

4.  USES. — Proust  suggested  that,  for  economy,   it  might  be  em- 
ployed in  artifical  fire  works,  and  that  5  parts  of  it,  with  1  of  char- 
coal and  1  of  sulphur,  will  burn  three  times  as  long  as  common  gun- 
powder,  and   of  course  make  a  more  enduring   exhibition.     When 
thrown  on  a  shovel  full  of  burning  coals  it  produces  a  peculiar  orange 
yellow  flame. 

5.  NATURAL  SOURCES. — It  had  been  thought  that  this  salt  was  un- 
known as  a  natural  production,  but  it  has  been,   within  a  few  years, 
discovered   in  Peru,  in  the   district  of  Atacama,  near  the  port  of 
Yquique  ;  it  is  in  strata  of  variable  thickness,  under  clay,   extending 
fifty  leagues,  and  in  some  places  it  is  quite  pure.     The  proprietor  had, 
at  the  date  of  the  account,  obtained  from  it  40000  quintals.* 

NITRATE   OF    AMMONIA. 

1.  HISTORY  AND  NAME. — Long  known  ond  formerly  called  nitrvm 
flammans  and  semivolatile.     Our  accurate  knowledge  of  its  properties 
is  derived,  principally,  from  Berthollet  and  Davy. 

2.  PREPARATION. 

(a.)  Bring  into  contact,  in  a  glass  globe  with  two  necks,  the  vapor 
of  strong  nitric  acid  and  ammoniacal  gas,  (in  an  apparatus  like  that 
on  p.  385,)  when  nitrate  of  ammonia  will  be  precipitated,  at  first 
concrete,  but  which  will  soon  deliquesce  and  then  crystallize  in  prisms. 

(b.)  The  best  mode  is  to  saturate  diluted  nitric  acid  with  con- 
crete carbonate  of  ammonia;  evaporate  with  a  gentle  heat  and  crys- 
tallize, f  If  the  evaporation  has  been  performed  between  70°  and 
100°  Fahr.  the  crystals  are  hexahedral  prisms  crowned  by  long 
hexahedral  pyramids;  if  at  212°,  they  are  in  silky  fibres;  if  at  300°, 
the  solution  concretes  without  crystallization. 

3.  PROPERTIES. 

(a.)   Taste,  bitter  and  cool.     Sp.gr.  1.5785. 

(b.)  Soluble  at  60°,  in  twice,  and  at  212°,  in  half  its  weight  of 
water  ; f  deliquescent. 

(c.)   The  acids,  especially  the  sulphuric,  decompose  it. 

The  fibrous  or  prismatic  crystals  melt  at  230°,  or  below  300°  ; 
ebullition,  but  without  decomposition,  commences  between  360°  and 
400° ;  decomposition  begins  at  450°,  and  between  that  and  500°,  it 
affords  the  pure  protoxide  of  nitrogen. 

*  Ann.  de  Chim.  et  de  Phys.  XVIII,  p.  442,  and  Thenard,  III,  265. 

t  A  few  embers,  under  an  earthen  dish,  are  sufficient:  hot  coals  would  volatilize 
and  decompose  the  salt.  The  common  aquafortis  need  not  be  diluted.  The  solu- 
tion is  in  a  good  state  to  crystallize,  when  a  twitching  pellicle  forms  on  the  surface, 
and  when  a  knife  blade  dipped  in  the  solution  and  waved  in  the  air  is  speedily  cov- 
ered with  small  crystals. 

t  Dr.  Hope  says,  that  it  dissolves  at  50°,  in  its  own  weight  of  water,  and  gener- 
ates 46°  of  cold. 


NITRATE  OF  AMMONIA.  475 

(d.)  The  compact  nitrate  suffers  no  change  below  260° ;  from  275° 
to  300°,  it  sublimes  slowly,  without  suffering  decomposition  or  becom- 
ing fluid;  at  320°  it  melts,  and  from  340°  to  380°,  is  decomposed 
partly  sublimed,  and  yields  the  above  mentioned  gas.*  If  the  tem- 
perature does  not  rise  above  500°,  the  salt  is  ivholly  decomposed  and 
converted  into  nitrous  oxide  and  water,  in  the  proportion  of  about  3 
parts  of  gas  to  1  of  water. 

100  grains  of  the  salt  afford  84  cubic  inches  of  the  gas. 

The  hydrogen  of  the  ammonia,  ivith  one  proportion  of  the  oxygen 
of  the  nitric  acid  forms  water  ;  the  remainder  of  the  oxygen  and  of 
the  nitrogen,  forms  the  nitrous  oxide  gas. 

(e.)  At  600°  and  above,  this  salt  explodes  by  the  reaction  of  its 
own  elements,  being  converted  into  nitrous  acid,  nitric  oxide  gas,  wa- 
ter and  nitrogen  gas. 

(/.)  On  red  hot  iron  or  any  other  ignited  body,  it  deflagrates  beauti- 
fully with  a  rich  yellow  flame,  and  exhibits  a  singular  instance  of  a 
burning  saline  body  ;  the  reaction  of  the  oxygen  of  its  acid  with  the 
hydrogen  of  its  base,  produces  the  rapid  combustion.  Hence  its 
old  name  of  nitrum ,flammans. 

4.  USES. — They  are  limited  to  the  formation  of  nitrous  oxide, 
and  to  some  cases  in  chemistry,  when  we  wish,  by  heat,  to  oxidize 
substances,  and  to  have  no  residuum ;  the  nitrate  of  potassa  always 
leaves  that  alkali  free  or  combined,  but  the  nitrate  of  ammonia  when 
deflagrated,  leaves  nothing  behind. 

5.  ALKALIES  AND  EARTHS. — Baryta,  strontia,  potassa,  soda,  and 
lime,  by  trituration  in  the  cold,  attract  the  acid  and  liberate  the  am- 
monia. 

6.  EQUIVALENT  NUMBER  AND  COMPOSITION. — This  salt  is  com- 
posed of  acid,   1  proportion,  54,  ammonia,  17  =  71,  for  the  dry  salt, 
and  according  to  Berzelius,  1  proportion  of  water  9,  for  the  prismatic 
variety,  =80. 

The  proportions  of  Berzelius,  are  for  the  100  parts — acid,  67.625, 
base,  21.143,  water,  11.232  =  100.00f 

The  composition  according  to  Davy,  is  for  the 
Prismatic  crystals,  69.5     Fibrous,  72.5     Compact,  74.5,  acid. 

"         "  18.4         "          19.3  "          19.8,  ammonia. 

"         "  12.1         "  8.2  "  5.7,  water. 


100.  100.  100. 


*  According  to  my  experience,  the  compact  nitrate,  if  not  very  carefully  dried, 
(which  is  difficult  on  account  of  the  fluid  imbibed  by  its  pores,)  is  apt  to  puff  up  in. 
the  retort,  with  a  violent  effervescence  of  aqueous  vapor ;  while  the  dry  prismatic 
nitrate  is  perfectly  manageable,  and  is  decomposed  with  great  steadiness  and  unifor- 
mity. 

t  Ann.  de  Chim.  T.  LXXX,  p.  182. 


476  NITROUS  OXIDE. 

NITROUS  OXIDE PROTOXIDE  OF  NITROGEN. 

Remarks. — It  has  already  been  stated  that  this  oxide  has  been  re- 
served for  the  present  place,  because  it  will  be  best  understood  in  con- 
nexion with  the  salt  from  ivhich  it  is  always  obtained.  Otherwise  it 
would  naturally  have  been  introduced  after  nitrogen  and  before  its 
deutoxide,  the  nitric  oxide  gas. 

1.  HISTORY. — Discovered  by  Dr.  Priestley,  in  1772,  by  whom  it 
was  called  dephlogisticated  nitrous  air  ;  Mr.  Davy  examined  it  with 
more  particular  care,  and  called  it  nitrous  oxide. 

2.  PREPARATION. 

(a.)  The  nitric  oxide  can  be  converted  into  the  nitrous  oxide,  by 
the  action  of  various  substances  which  will  abstract  half  the  oxygen ; 
they  will  be  mentioned  in  an  appendix  to  this  article. 

(b.)  But  the  only  eligible  method  is  by  the  decomposition  of  the 
nitrate  of  ammonia  by  heat.* 

(c.)  The  solid  nitrate,  which  should  be  as  dry  as  possible,  should 
not  Jill  more  than  one  quarter  the  body  of  the  retort — a  good  Ar- 
gand's  lamp  or  a  few  live  coals  are  sufficient  for  the  decomposition, 
which  is  known  to  be  proceeding  well,  when  the  melted  materials  boil 
quietly  and  emit  small  bubbles ;  a  thin  snowy  vapor  revolving  in  the 
retort,  and  no  red  fumes  appearing.  If  the  heat  is  raised  too  high, 
the  bubbles  will  be  very  large,  and  a  reddish  tinge  in  the  retort  will 
indicate  the  formation  of  nitrous  acid  vapor. 

3.  THEORY  OF  THE  DECOMPOSITION  AND  EQUIVALENT  NUMBER. 

(«.)  The  nitrate  of  ammonia  is  composed  entirely  of  the  pondera- 
ble part  of  gases,  and  the  effect  of  the  heat  is  so  to  rearrange  them, 
by  the  exertion  of  new  affinities,  that  the  solid  is  converted,  wholly, 
into  aerial  products  ;  steam,  and  nitrous  oxide. 

(b.)  The  nitrate  of  ammonia  is  composed  of  one  proportion  of  ni- 
tric acid  54,  and  one  of  ammonia  17=71. 

The  acid  is  composed  of  nitrogen,  1  proportion,  14,  and  oxygen,  5 
proportions,  8x5=40=54. 

The  alkali  consists  of  nitrogen,  1  proportion,  14,  and  hydrogen,  3 
proportions,  1x3=3=17. 

(c.)  The  representative  or  equivalent  number  of  nitrous  oxide  is  22, 
made  up  of  I  proportion  of  nitrogen  14,  and  1  of  oxygen,  8=22. 

(of.)  During  the  decomposition,  71  grains  of  the  salt  afford  27  of 
water,  consisting  of  3  proportions,  viz.  9x3,  and  water  is  composed 
of  I  proportion  of  hydrogen  I,  and  1  of  oxygen,  8=9;  there  are 
produced  also,  44  grains  of  nitrous  oxide,  consisting  of  two  propor- 
tions, or  22x2. 


*  In  addition  to  what  has  been  already  said  under  the  nitrate  of  ammonia,  we  will 
observe  that,  notwithstanding  the  statements  under  2,  (c,  d,  and  e,)  it  is  not  necessa- 
ry to  use  a  thermometer  to  regulate  the  decomposition  of  this  salt. 


NITROUS  OXIDE.  477 

The  three  proportions  of  water  consist  ofoxy.  24+hydrog.  3=27 
two  "  nitrous  oxide  1 6  -\-nitr og.  28=44 

71* 

(e.)  This  view  supposes  the  nitrate  of  ammonia  to  be  anhydrous, 
and  all  the  water  that  appears  during  the  decomposition,  to  be  gener- 
ated and  not  evolved. 

It  is  a  beautiful  example  of  the  arrangement  of  principles  in  defi- 
nite proportions,  so  that  with  a  complete  decomposition  and  a  forma- 
tion of  new  products,  there  is  no  loss. 

4.  PROOFS  OF  THE  PURITY  OF  THE  GAS. 

(a.)  When  the  mouth  is  applied  to  a  bottle  of  it,  a  distinctly  sweet- 
ish taste  is  perceived,  without  any  corrosiveness  or  peculiar  smell.f 

(I.)  Entirely  absorbed  by  agitation  ivith  about  its  own  volume  of 
water,  that  has  been  previously  boiled,  and  become  cold  without  the 
access  of  air.  The  saturated  water  will  have  a  sweetish  taste,  and 
faint  agreeable  odor,  and  the  gas  will  be  expelled,  unaltered,  by  boil- 
ing ;  the  solution  does  not  redden  the  vegetable  blue  colors,  or  pro- 
duce any  exhilirating  effects. 

(c.)  JVb  red  fumes  are  produced  by  mingling  this  gas  with  oxygen 
gas  or  common  air,  which  would  happen  if  nitric  oxide  gas  were 
present ; 

(d.)  Nor,  on  the  other  hand,  does  nitric  oxide  gas  produce  any 
change  of  color  or  absorption,  as  it  would  do  if  free  oxygen  gas  were 
mingled  with  it. 

(e.)  It  is  not  diminished  by  agitation  with  green  sulphate  of  iron, 
which  would  be  the  fact  if  nitric  oxide  were  present. 

(/.)  It  is  not  acid. 

5.  PHYSICAL,  PROPERTIES. 
(«.)  Colorless — transparent. 

(b.)  Specific  gravity,  1.5277,  common  air  being  1. 

(c.)  Weight  for  100  cubic  inches  of  the  gas  at  medium  tempera- 
ture and  pressure,  46.596  ;  this  appears  also  from  its  constitution, 
which  is  nitrogen  100  cubic  inches,  weighing  29.652  grains,  and  ox- 
ygen, 50  cubic  inches,  weighing  16.944  grains,  =46. 596, J  the  150 
volumes  of  gases  being  condensed  into  100. 


*  Turner. 

t  Provided  it  has  stood  long  enough  over  water  to  'absorb  any  saline  or  acid  vapor, 
for  which  one  hour  and  sometimes  half  an  hour  is  sufficient. 

t  Dr.  Prout,  as  has  been  already  observed,  introduced  the  rule  that  the  atomic  or 
representative  number  of  a  gas  multiplied  into  the  specific  gravity  of  oxygen,  if  that 
be  unity,  or  of  hydrogen,  if  that  be  unity,  will  give  the  specific  gravity  of  the  gas 
in  question — thus,  if  oxygen  be  unity,  then  the  representative  number  of  nitrous 
oxide  is  2.75  and  2.75  X  by  .555  =1.526  or  the  equivalent  hydrogen  being  unity,  is 
22,  which  X  .0694  =  1.526. 


478  NITROUS  OXIDE. 

6.  ACTION  OF  COMBUSTIBLES. 

(a.)  JL  lighted  candle  burns,  with  increased  brilliancy  in  this  gas, 
and  with  a  white  flame,  which,  before  extinction,  appears  edged  with 
blue. 

(b.)  Dr.  Turner  states,  that  an  extinguished  candle  retaining  "  a 
red  wick,"  is  lighted  again  by  immersion  in  this  gas.* 

(c.)  Sulphur  burning  with  a  blue  flame,  is  immediately  extinguish- 
ed; but  with  a  white  flame,  that  is,  at  a  higher  temperature,  it  hums 
vividly,  and  the  flame  becomes  rose-colored. 

(d.)  Phosphorus  may  be  melted,  and  if  touched  with  a  red  hot  wire, 
it  may  be  even  sublimed  in  this  gas  without  burning  ;  but  if  touched 
with  a  white  hot  iron  the  phosphorus  burns  almost  explosively. 

The  jar  should  be  strong,  not  more  than  one  eighth  filled  with 
the  gas,  and  the  wire  well  curved,  so  that  it  may  be  expeditiously 
withdrawn  ;  not  unfrequently  the  jar  bursts  in  the  experiment.  The 
combustion  ceases  when  about  one  half  the  gas  is  consumed,  and 
the  product  is  phosphoric  acid,  nitrogen  being  evolved. 

(e.)  If  the  phosphorus  be  already  on  fire  when  it  is  introduced,  it 
continues  to  burn  but  with  increased  splendor,  greater  than  we  should 
infer  from  the  proportion  of  oxygen  which  the  gas  contains. 

(f.)  Charcoal,  vividly  ignited,  is  said  to  burn  in  this  gas  more  bril- 
liantly than  in  common  air,f  and  if  properly  managed  to  produce, 
for  each  measure  of  nitrous  oxide,  one  of  nitrogen,  and  half  a  meas- 
ure of  carbonic  oxide,  equivalent  to  half  a  measure  of  oxygen.f 

(g.)  Hydrogen  gas,  mingled,  volume  for  volume  with  this  gas,  ex- 
plodes by  the  contact  of  flame,  and  by  its  acid,  the  nitrous  oxide  is 
decomposed  by  spongy  platinum  at  the  common  temperature. 

With  40  hydrogen  to  39  nitrous  oxide,  there  remains  only  nitro- 
gen, and  if  the  proportion  of  hydrogen  is  smaller,  some  nitric  acid 
is  produced. §  In  general,  the  products  of  the  combustion  of  hydro- 
gen in  nitrous  oxide,  are  the  same  as  in  oxygen,  or  in  common  air, 
and  nitrogen  remains  equal  in  volume  to  the  original  gas. 

(h.)  Pyrophorus  does  not  take  flre  spontaneously  in  this  gas,  but 
it  takes  fire  if  touched  with  an  iron  strongly  heated,  but  not  to  igni- 
tion. It  is  the  only  body  which  burns  in  this  gas,  at  a  temperature 
below  ignition. 

Si.)  Phosphuretted  hydrogen  flashes  in  this  gas. 
j.)  Potassium  and  sodium  decompose  it  below  a  red  heat,  evol- 
ving nitrogen,  and  forming  alkali. 


*  This  has  never  succeeded  with  me. 

t  In  this  experiment  I  have  never  been  able  to  succeed. 

*  Henry.  §  Ibid. 


NITROUS  OXIDE.  479 

(k.)  "An  iron  wire  burns  in  this  gas  nearly  as  well  as  in  oxygen 
gas." 

7.  COMPOSITION. 

(a.)  The  equivalent  number  of  this  gas  has  been  already  stated 
to  be  22. 

(b.)  As  two  volumes  of  nitrous  oxide  require,  for  decomposition, 
two  volumes  of  hydrogen,  which  can  saturate  only  one  volume  of 
oxygen  ;  it  follows  that  the  residuary  nitrogen,  which  is  found  to  be 
expanded  into  two  volumes,  was  combined  with  1  measure  of  oxygen, 
and  that  the  three  were  condensed  into  two  ;  or  one  volume  of  ni- 
trogen combines  with  half  a  volume  of  oxygen,  and  the  volume  and 
a  half  occupy  one  volume,  as  before  stated  under  specific  gravity ; 
one  volume  of  nitrogen,  or  1  proportion,  is  14,  and  half  a  volume  of 
oxygen  is  8,  and  8  +  14=22. 

(c.)  Ammoniacal  gas  100  measures -\-15Q  nitrous  oxide,  produce 
a  combustible  mixture ;  the  oxygen  of  the  oxide  uniting  with  the  hy- 
drogen of  the  ammonia. 

(d.)   Olejiant  gas  burns,  when  mingled  with  this  gas  and  ignited. 

(e.)  Carbonic  oxide  1  vol.  -{-nitrous  oxide  1  vol.  fired  by  the  elec- 
tric spark,  over  mercury,  produce  1  vol.  carbonic  acid,  and  1  vol.  of 
nitrogen. 

This  method  of  analysing  nitrous  oxide  was  introduced  by  Dr. 
Henry.* 

Let  1 100  measures  of  nitrous  oxide,  proved,  by  agitation  with 
green  sulphate  of  iron,  to  be  free  from  nitric  oxide,  be  fired  with  a 
slight  excess,  say  110  or  115  measures  of  pure  carbonic  oxide, f  and 
100  measures  of  carbonic  acid  will  be  obtained. 

(f.)  If  this  gas  be  electrized  in  a  tube  over  mercury,  it  is  partially 
decomposed,  being  converted  into  nitrous  acid,  and  common  air,  and 
a  similar  effect  is  produced  by  passing  it  through  a  thoroughly  ignited 
porcelain  tube,  glazed  within  and  without. 

8.  CONDENSATION  OF  NITROUS  OXIDE. 

(a.)  Effected  by  Mr.  Faraday,^  by  means  similar  to  those  that  have 
been  already  described  in  the  case  of  other  gases.  Some  nitrate  of 
ammonia,  rendered  very  dry,  by  a  partial  decomposition  by  heat,  in 
the  air,  was  placed  in  the  end  of  a  recurved  tube,  sealed  at  both  ex- 
tremities ;  the  end  containing  the  salt  was  then  heated,  while  cold 
was  applied  to  the  other  end,  by  a  mixture  of  ice  and  snow. 

(b.)  Two  fluids  were  obtained,  the  one  water,  with  a  little  nitrous, 
acid  and  oxide,  and  the  other,  floating  upon  it,  being  very  mobile> 
limpid,  and  colorless,  was  the  liquified  nitrous  oxide. 


*  Ann.  of  Phil.  N.  S.  Vol.  VII,  p.  299. 

t  Previously  washed  with  a  solution  of  caustic  potash. 

t  Phil.  Trans.  1823,  p.  195. 


480  NITROUS  OXIDE. 

(c.)  It  was  so  volatile}  that  the  warmth  of  the  hand,  although  un- 
der so  great  a  pressure,  converted  it  into  vapor,  and  it  boiled  readily 
by  the  difference  between  0  and  50°.  In  refractive  power  it  was  in- 
ferior to  any  known  fluid,  not  excepting  even  the  other  condensed 
gases.  It  remained  fluid  at  — 10°.  When  the  tube  was  opened  in 
the  air,  the  fluid  instantly  burst  into  gas,  and  another  tube  being 
opened  under  water,  the  fluid  rushed  again  into  the  form  of  gas, 
which  was  collected. 

(d.)  To  estimate  the  pressure,  a  trumpet  shaped  capillary  tube, 
containing  a  globule  of  mercury,  after  being  graduated,  by  the  pas- 
sage of  the  mercury  through  the  different  parts  of  the  tube,  was  seal- 
ed at  one  end,  and  introduced  into  the  larger  tube,  before  it  was 
closed.  The  movement  of  the  mercury  indicated  the  pressure,  and 
when  it  became  stationary,  the  force,  at  45°,  appeared  to  be  equal  to 
50  atmospheres,  and  50  X  15  =  750  Ibs.  upon  the  square  inch.  At  32° 
the  pressure  was  44  atmospheres,  and  15  X  44 =660  pounds  on  the 
square  inch  ;  12  degrees  of  temperature  having  added  to  its  pressure 
7  atmospheres,  or  105  pounds,  or  nearly  9  pounds  for  each  degree. 
Mr.  Faraday  always  subtracted  1  atmosphere  for  the  air  in  the  tubes 
when  the  experiment  began. 

9.     EFFECTS  ON  ANIMAL  LIFE. 

(a.)  Warm  blooded  animals,  confined  in  nitrous  oxide  speedily 
die*  and  fishes  expire  in  water  impregnated  with  it.f  For  many 
years  after  its  discovery,  no  suspicion  was  entertained  that  it  was  res- 
pirable. 

(b.)  This  gas  is  not  only  respirable,  but  it  is  the  most  powerful 
stimulant  known. ,f 

(c.)  This  was  first  ascertained  by  Sir  H.  Davy,  in  a  series  of 
trials  on  respiration,  some  of  them  very  hazardous,  which  he  made 
upon  his  own  person ;  the  results  may  be  found  in  his  Researches, 
from  which  the  following  passage  is  extracted,  p.  487. 

"  Having  previously  closed  my  nostrils,  and  exhausted  my  lungs, 
I  breathed  four  quarts  of  nitrous  oxide  from  and  into  a  silk  bag. 
The  first  feelings  were  similar  to  those  produced  in  the  last  experi- 
ment, (giddiness) ;  but  in  less  than  half  a  minute,  the  respiration  be- 
ing continued,  they  diminished  gradually,  and  were  succeeded  by  a 
sensation  analogous  to  gentle  pressure  on  all  the  muscles,  attended 
by  a  highly  pleasurable  thrilling,  particularly  in  the  chest  and  the  ex- 


*  Dr.  Ure,  (Diet.  2d  Ed.  p.  619,)  says  that  mice  die  more  speedily  than  when  im- 
mersed in  nitrogen,  hydrogen,  or  carbonic  acid. 

t  The  blood  acquires  a  purple  color  in  consequence  of  the  respiration  of  this  gas, 
and  after  death  the  muscles  of  animals  are  found  to  have  lost  their  irritability. 

t  It  is  said  that  if  a  little  sulphate  or  muriate  of  ammonia  be  mixed  with  this  ni- 
trate, this  salt  will  not  afford  an  exhilirating  gas. — Ure. 


NITROUS  OXIDE.  481 

tremities.  The  objects  around  me  became  dazzling,  and  my  hear- 
ing more  acute.  Towards  the  last  inspiration  the  thrilling  increased, 
the  sense  of  muscular  power  became  greater,  and  at  last  an  irresist- 
ible propensity  to  laughter  was  indulged  in ;  I  recollect  but  indis- 
tinctly what  followed  ;  I  know  that  my  motions  were  various  and 
violent.  These  effects  soon  ceased  after  respiration.  In  ten  min- 
utes I  had  recovered  my  natural  state  of  mind.  The  thrilling  in  the 
extremities  continued  longer  than  the  other  sensations." 

(d.)  "  The  effects  of  the  nitrous  oxide  on  the  human  system  are 
analagous  to  a  transient,  peculiar,  various,  and  generally  very  viva- 
cious ebriety." — Dr.  Hare. 

(e.)  It  differs  from  all  other  diffusible  stimuli  in  not  being  attend- 
ed by  any  subsequent  depression  ;  in  general,  on  the  contrary  the 
violent  effects  gradually  subside  into  cheerfulness,  and  manifest  them- 
selves by  gayety  and  activity,  which  sometimes  continue  for  hours, 
and  even  in  particular  cases  for  days. 

(f.)  The  general  dose  is  from  4  to  6  or  S  quarts  of  the  gas.  JIX 
(g.)  It  is  breathed  into  and  from  a  silk  bag,  or  an  air 
jar  furnished  with  a  stop  cock,  of  a  wide  bore,  or  with 
a  arge  bent  tube,  as  in  the  annexed  cut :  and  the  action 
ofl  the  lungs  may  be  relieved  by  having  an  assistant  to  hold 
the  jar  over  the  well  of  the  pneumatic  cistern,  so  that  it, 
may  rise  and  fall;  a  small  gasometer  is  still  more  con-= 
venient. 

(h.)  The  effects  are  not  always  agreeable.  Some  persons  are  not 
excited,  but  are  rather  depressed,  and  also  fatigued,  by  the  constrained 
mode  of  breathing.  Some  become  faint  and  fall  as  in  a  Jit  or  swoon; 
but  they  in  general  soon  recover,  as  if  from  a  troubled  dream  or  a  turn 
of  nightmare ;  some  are  rendered  apparently,  apoplectic,  and  others 
are  thrown  into  a  temporary,  but  often  violent  delirium,  and  in  such 
cases  the  subsiding  feelings  are  disagreeable. 

(i.)  There  is  good  ground  for  caution,  and  it  would  now  be 
proper  that  the  practice  of  breathing  the  nitrous  oxide  should  be  dis- 
continued, except  for  medical  purposes.* 

Remark. — Although  we  can  offer  no  satisfactory  theory  to  account 
for  the  action  of  the  nitrous  oxide,  it  cannot  but  be  regretted,  that  so 
powerful  a  stimulus  both  of  our  physical  and  inellectual  powers  should 

*  Among  multitudes  to  whom  I  have  administered  this  gas,  about  6  out  of  8  have 
been  agreeably  affected  ;  but  there  has  been  very  great  variety  in  the  appearances, 
influenced,  in  most  cases,  apparently,  by  the  physical  and  moral  temperament  of  the 
subject.  I  have  seen  not  a  few  cases  attended  by  symptoms  so  violent  and  alarming 
that  I  have  been  very  glad  when  they  have  subsided.  I  have  personally  known 
no  instance  of  fatal  effects,  either  immediate  or  remote ;  but  some  have  thought 
themselves  injured  for  a  considerable  period,  and  it  has  always  been  a  subject  of 
anxiety  lest  some  idiosyncrasy  should,)  produce  an  unhappy  termination.  The  ex- 
perience of  Thenard,  Vanquelin,  and  their  companions  was  altogether  painful. 
See  Thenard's  Chem. 

61 


482  NITROUS  OXIDE. 

remain  a  subject  of  mere  curiosity  or  merriment.  Differing  from 
every  other  stimulus,  in  not  producing  depression  correspondent  to 
the  excitement;  why  should  it  not  be  employed  as  a  general  tonic  and 
as  a  comforting  reviving  remedy  ?  In  cases  of  great  debility,  it  clear- 
ly ought  not  to  be  used  in  such  doses,  as  to  produce  violent  effects, 
but  rather  such  as  are  gentle  and  longer  continued,  which  might  then 
be  more  frequently  renewed.  It  would  be  proper  to  begin  with  di- 
luting the  gas  one  half  or  more,  with  common  air,  and  the  strength 
and  quantity  might  thus  be  graduated  to  the  state  and  strength  of  the 
patient.  A  larger  gasometer  being  employed,  the  desired  dose 
might  be  drawn  off  into  a  smaller  one,  and  the  gases  being  used  over 
the  same  water,  there  need  be  no  loss  by  absorption.  In  the  Ameri- 
can Journal,  Vol.  V,  p.  196,  may  be  seen  an  account  of  a  person 
whose  health  of  body  and  mind  was  restored  by  the  respiration  of  this 
gas;  and  although  it  was  attended  by  the  singular  circumstance, 
that  he  had  acquired  suddenly  such  a  taste  for  sweets,  that  he  cra- 
ved sugar  and  molasses  on  all  his  food,  even  that  of  an  animal  kind, 
and  this  taste  was  freely  indulged,  still  his  health  was  permanently 
invigorated,  and  the  acquired  taste  gradually  left  him.* 


*  Apparatus  for  evolving  and  preserving  nitrous  oxide  gas. — Dr.  Hare. 

A,  represents  a  copper  vessel  of  about  18  inches  in  height,  and  nine  inches  in 
diameter,  which  is  represented  as  heing  divided  longitudinally  in  order  to  show  the 
inside.  The  pipe,  B,  proceeds  from  it  obliquely,  as  nearly  from  the  bottom  as  possible. 

Above  that  part  of  the  cylinder  from  which  the  pipe  proceeds,  there  is  a  diaphragm 
of  copper,  perforated  like  a  cullender.  A  bell  glass  is  surmounted  by  a  brass  cock, 
C,  supporting  a  tube  and  hollow  ball,  from  which  proceed,  on  opposite  sides,  two 
pipes,  terminating  in  gallows  screws,  D  D,  for  the  attachment  of  perforated  brass 
knobs,  soldered  to  flexible  leaden  pipes  communicating  severally  with  leathern  bags, 
F  F.  The  larger  bag,  is  capable  of  holding  about  fifty  gallons,  the  smaller  one 
about  fifteen  gallons. 

The  beak  of  the  retort  must  be  long  enough  to  eriter  the  cylinder,  so  that  the  gas 
in  passing  from  the  mouth  of  the  beak,  may  rise  under,  and  be  caught  by  the  dia- 
phragm. This  is  so  hollowed  as  to  cause  it  to  pass  through  the  perforations  already 
mentioned,  which  are  all  comprised  within  a  circle,  less  in  diameter,  than  the  bell 
glass.  The  gas  is,  by  these  means,  made  to  enter  the  bell  glnss,  and  is,  previously 
to  its  entrance,  sufficiently  in  contact  with  water,  to  be  cleansed  from  the  acid  vapor 
which  usually  accompanies  it.  On  account  of  this  vapor,  the  employment  of  a 
small  quantity  of  water  to  wash  the  gas,  is  absolutely  necessary  ;  and  for  the  same 
reason,  it  is  requisite  to  have  the  beak  of  the  retort  so  long,  as  to  convey  the  gas  into 
the  water,  without  touching  the  metal;  otherwise,  the, acid  vapor  will  soon  corrode 
the  copper  of  the  pipe,  B,  so  as  to  enable  the  gas  to  escape.  But  while  a  small 
quantity  of  water  is  necessary,  a  large  quantity  is  productive  of  waste,  as  it  absorbs 
its  own  bulk  of  the  gas.  On  this  account,  I  contrived  this  apparatus,  in  preference 
to  using  gazometers  or  air  holders,  which  require  larger  quantities  of  water. 

The  seams  of  the  bags  are  closed  by  means  of  rivets,  agreeably  to  the  plan  of 
Messrs.  Sellers  &  Pennoch  for  fire  hose.  The  furnace  is  so  contrived,  that  the  coals, 
being  situated  in  a  drawer,  G,  may  be  partially,  or  wholly  removed,  in  an  instant. 
Hence  the  operator  is  enabled,  without  difficulty,  to  regulate  the  duration  or  the  de- 
gree of  the  heat.  This  control  over  the  fire,  is  especially  desirable  in  decomposing 
the  nitrate  of  ammonia,  as  the  action  may  otherwise  become  suddenly  so  violent,  as 
to  burst  the  retort.  The  iron  netting,  represented  at  N,  is  suspended  within  the 
furnace,  so  as  to  support  the  glass  retort,  for  which  purpose  it  is  peculiarly  adapted. 
The  first  portions  of  gas  which  pass  over,  consisting  of  the  air  previously  in  the  re- 


484  NITROUS  OXIDE. 

APPENDIX  RELATING  TO  NITROUS  AND  NITRIC  OXIDE  GAS. 

1 .  Sulphite  of  potash,  pulverized  and  retaining  its  water  of  crys- 
tallization,  100  grains,  in  1  hour,  reduced  16  cubic  inches  of  nitric 
oxide  gas  to  7.8  of  nitrous  oxide. 

2.  Dry  muriate  of  tin,  dry  alkaline  sulphurets  and  iron  filings,  in 
a  few  days,  convert  the  nitric  oxide  gas  into  nitrous  oxide. 

3.  Dry  nitric  oxide  gas  and   dry  sulphuretted  hydrogen,  slowly 
decompose   each   other  ;    sulphur  is   deposited   and  nitrous  oxide 
formed. 

4.  In  all  the  above  cases,  the  presence  of  water  aids  the  decom- 
position. 

5.  Zinc,  in  contact  with  water  and  nitric  oxide  gas,  converts  the 
latter  into  nitrous  oxide,  and  ammonia  is  also  produced. 

6.  Nitrous  oxide  is  produced  during  the  solution  of  several  of  the 
metals  in  nitric  acid. 

7.  Zinc  or  tin  dissolved  in  nitric  acid,  diluted  with  five  or  six  times 
its  weight  of  water,  gives  this  gas  ;  zinc  in  large  pieces  gives  nitrous 
oxide,  till  the  acid  begins  to  be  of  a  brown  color,  when  nitric  oxide 
gas  is  formed ;  the  gas  from  the  solutions  of  the  metals  is  never  pure. 

8.  Iron  produces  it  mixed  with  nitric  oxide  gas. 

9.  A  cold  saturated  solution  of  nitrate  of  iron  gives  out  much  of  it. 

10.  Nitrate  of  zinc,  distilled  to  dryness — the  same. 

11.  If  sulphite  of  potash,  mixed  with  caustic  potash,  retaining  its 
water  of  crystallization,  be  immersed  in  an  atmosphere  of  nitric  oxide 
gas,  the  latter  will  become  nitrous  oxide  and  this  will  combine  with 
the  potash ;  the  sulphate  of  potash  and  remaining  sulphite  are  crys- 
tallized out,  and  the  compound  of  nitrous  oxide   and  potash  is  ob- 
tained pure,  except  some  carbonate  of  potash.. 

12.  This  salt  is  very  soluble  in  water ;  is  caustic  and  pungent  to 
the  taste ;  turns  green  the  alkaline  test  liquors,  and  contains  about  J 
nitrous  oxide,  which  is  not  expelled  by  boiling ;  powdered  charcoal 
mixed  with  it  burns  with  scintillation,  and  all  acids  expel  the  nitrous 
oxide. 

13.  By  similar  means  a  compound  with  soda  may  be  formed,  em- 
ploying the  sulphite  of  soda,  &c. 


tort,  are  to  be  allowed  to  escape  through  the  cock,  H.  As  soon  as  the  nitrous  oxide 
is  evolved,  it  may  be  detected  by  allowing  a  jet  from  this  cock,  to  act  upon  the  flame 
of  a  taper. 

To  obtain  good  nitrous  oxide  gas,  it  is  not  necessary  that  the  nitrate  of  ammonia 
should  be  crystallized  ;  nor  does  the  presence  of  a  minute  quantity  of  muriatic  acid, 
interfere  with  the  result.  I  have  employed  advantageously  in  the  production  of  this 
gas,  the  Concrete  mass  formed  by  saturating  strong  nitric  acid,  with  carbonate  of 
ammonia. 

The  saturation  may  be  effected  in  a  retort,  and  the  decomposition  accomplished  by 
exposing  the  compound  thus  formed  to  heat,  without  further  preparation. 


NITRATES  OF  EARTHS.  485 

NITRATES  OF  THE  EARTHS. 

General  characters. 

1.  Similar  to  those  of  the  nitrates  of  the  alkalies,  but  their  action 
on  ignited  combustible  bodies  is  less  vigorous ;  they  rather  scintillate 
than  deflagrate  on  burning  coals,  but  are  eventually  decomposed  both 
by  heat  and  by  hot  combustibles. 

2.  In  some  of  them,   as  the  nitrates  of  strontia  and  baryta,  the 
acid  is  decomposed  at  once  into  nitrogen  and  oxygen,  without  the 
formation  of  a  nitrite ;  the  base  being  left  behind. 

3.  Sulphuric  acid  evolves  the  nitric  acid. 

4.  Only  two  of  the  earthy  nitrates*  are  found  native,  the  rest  be- 
ing formed  by  art. 

NITRATE  OF  BARYTA. 

1.  DISCOVERY. — First    formed    by    Scheele   and   Bergman,   in 
1776. 

2.  PREPARATION. 

(a.)  By  decomposing  the  carbonate  of  baryta,  native  or  artificial,  by 
the  nitric  acid,  diluted  with  from  8  to  16  times  its  volume  of  water ; 
the  effervescence  is  moderate. 

(b.)  By  decomposing,  by  the  nitric  acid,  the  artificial  hydro-sulphu- 
ret  of  baryta,  formed  from  the  decomposition  of  the  sulphate  by  char- 
coal ;  or,  a  carbonate  may  first  be  formed  by  precipitating  the  baryta 
from  the  solution  of  the  sulphuret  by  the  carbonate  of  an  alkali,  and 
then  this  may  be  decomposed  by  nitric  acid. 

3.  PROPERTIES. 

(a.)  Crystals  are  easily  obtained  from  the  evaporated  solution ; 
primitive  form,  the  octahedron — sometimes  in  brilliant  triangular 
plates,  with  truncated  angles ;  sometimes  grouped  in  stars. 

(b.)  Sp.  gr.  2.9.     Taste,  sharp  and  acrid. 

(c.)  Insoluble  in  alcohol,  but  soluble  in  12  parts  of  water  at  60°, 
and  in  about  3  or  4  at  212°.  Least  soluble  of  all  the  nitrates ;  nitric 
acid  being  poured  into  a  concentrated  solution  of  muriate  of  baryta, 
causes  a  precipitate  of  the  nitrate  which  more  water  redissolves. 

Solution  of  nitrate  of  baryta  should  not  cause  a  precipitate  with 
nitrate  of  silver. 

!d.)  Air  produces  little  change  upon  this  salt, 
e.)  Decrepitates  and  feebly  scintillates  on  burning  coals, 
(f.)    Decomposed  by  ignition   in  a  crucible,   and  affords  pure 
baryta,^  by  a  theory  already  explained.     If  decomposed  in  a  porce- 


*  Those  of  lime  and  magnesia. 

t  If  the  heat  is  urged  too  far,  it  vitrifies  in  an  earthen  crucible. 


486  NITRATES  OF  EARTHS. 

lain  retort,  by  a  regulated  heat,  the  deutoxide  may  be  obtained.  (See 
note,  p.  215.) 

(g.)  Strength  of  affinity. — Not  decomposed  by  any  single  base 
or  acid,  except  by  the  sulphuric  and  the  phosphoric  ;  decomposed 
by  all  the  soluble  sulphates,  and  by  the  carbonates  of  the  alkalies. 

4.  PROPORTIONS. — This  salt  is  anhydrous.  If  it  is  a  compound 
of  1  proportion  of  nitric  acid,  and  1  of  baryta,  its  composition  should 
be  baryta,  78,  per  cent.  58.4 

nitric  acid,  54,  41.6 


Its  equivalent,   132  100. 

From  this  result,  the  analyses  of  several  of  the  most  eminent  chem- 
ists are  not  very  remote. 

Clement  and  Desormes,      40       acid,  60       base. 

Jas.  Thomson,  40.7  59.3 

Berzelius,  41.54  58.46* 

5.  USE. 

!a.)  To  afford  pure  baryta  by  its  decomposition  by  heat. 
b.)  To  detect  sulphuric  acid. — In  examining  the  nitric  acid  for 
this  purpose  by  the  nitrate  of  baryta,  the  latter  must  be  dilute  unless 
the  former  is  so,  otherwise  the  strong  nitric  acid  will  precipitate  crys- 
tals of  nitrate  of  baryta,  presenting  a  false  indication  of  impurity ; 
their  ready  solubility  in  more  water  will  however  distinguish  them. 

Remark. — After  the  expulsion  of  the  nitric  acid  by  the  compound 
blowpipe,  the  earth  of  this  salt,  if  urged  by  the  heat,  exhibits  on  char- 
coal a  deep  yellow  flame,  and  ultimately  melts. 

NITRATE  OF   STRONTIA. 

1.  DISCOVERY. — By  Dr.  Hope,  of  Edinburgh. 

2.  PREPARATION. 

(a.)  By  dissolving  carbonate  of  strontia,  1  part,  in  nitric  acid  1, 
and  water  I ;  the  action  is  rapid;  carbonic  acid  is  disengaged,  and 
the  nitrate  of  strontia,  being  evaporated  over  a  lamp,  the  crystals  pre- 
cipitate during  the  process. 

(b.)  JBy  decomposing  the  sulphate  of  strontia  by  ignition  with  char- 
coal— and  then  decomposing  the  resulting  sulphuret  by  nitric  acid  ; 
or  it  may  first  be  turned  into  a  carbonate  by  a  carbonate  of  an  alkali. 

3.  PROPERTIES. 

(a.\   The  crystals  are  octahedra  or  six  sided  prisms.-^ 
(b.)    Taste  pungent  and  cooling, 
(c.)   Sp.  gr.  3. 


*  Quoted  by  Henry. 

t  See  Ann,  of  Phil.  N.  S.  VII,  288. 


NITRATES  OF  EARTHS.  487 

(d.)  Jit  60°,  dissolves  in  1  part  of  water,  and  at  212°,  in  some- 
what more  than  half  its  weight. 

(e.)  Alcohol  does  not  dissolve  it. 

(/.)  Deliquescent  in  moist  air  ;  efflorescent  in  a  dry  air. 

(g.)  Slightly  scintillates  on  burning  charcoal,  but  with  sulphur 
and  charcoal  in  the  proportions  of  gunpowder,  it  burns  slowly  and 
emits  purple  sparkles,  and  a  fine  green  flame. 

(h.)  Decomposed  by  ignition,  and  pure  strontia  remains.* 

(i.)  A  cry 'Stalin  a  burning  candle  produces  a  beautiful  blood  red 
flame. 

(j.)  The  flame  of  boiling  alcohol  also  acquires  a  red  color  from 
this  salt. 

(k.)  Decomposed  by  the  sulphuric  and  muriatic  acids,  and  by  baryta, 
potassa,  and  soda, 

4.  PROPORTIONS. — According  to  Richter,  this  salt  contains,  (ex- 
clusively of  water,)  acid  5 1. 4 -f  48. 6,  base.     Stromeyer  gives  acid 
50.62  +  49.38,  base.     These  proportions  agree  with  the  equivalent 
weight  of  the  acid  54,  and  of  the  base  52. — Henry. 

5.  USE. — To  afford  pure  strontia,  and  as  a  test  for  sulphuric  acid  ; 
it  is  to  be  used  with  the  same  precautions  as  the  nitrate  of  baryta. 

NITRATE  OF  LIME. 

1.  NATURAL  SITUATIONS. — In  the  nitre  beds  ;  in  the  nitrous  earths, 
and  particularly  in  those  of  the  caverns  in  the  limestone  of  the  wes- 
tern American  States ;  in  the  calcareous  cement  and  plaster  of  old 
buildings  that  have  long  been  inhabited.     Its  origin,  as  regards  the 
acid,  appears  to  be  from  the  atmosphere,  aided  at  least  in  some  cases, 
by  nitrogen  from  animal  effluvia. 

2.  PREPARATION. 

(a.)  By  dissolving  lime  or  its  carbonate  in  nitric  acid,  diluted  with 
5  or  6  parts  of  water,  evaporating  to  a  syrupy  consistence,  and  then 
allowing  it  to  cool  and  crystallize.  63  parts  of  carbonate  of  lime  are 
decomposed  by  90.23  of  nitric  acid  of  the  density  1.5  and  produce 
103.05  parts  of  dry  nitrate  of  lime. 

3.  PROPERTIES. 

(a.)  The  crystals  are  six  sided  prisms,  very  acutely  terminated ; 
more  frequently  it  is  in  fine  brilliant  needles. 

!b.)   Taste  acrid  and  bitter. 
c.)  Sp.gr.  1.6.     Suffers  the  aqueous  fusion  ;  if  kept  melted  for 
fae  or  ten  minutes  and  then  poured  into  a  heated  iron  pot,  it  becomes 
phosphorescent,  and  was  formerly  called  Baldwin's  phosphorus. f 


*  If  at  the  instant  of  decomposition,  a  combustible  substance  be  brought  into  contact 
with  it,  a  deflagration  with  a  very  vivid  red  flame  is  produced.     Dr.  Hope, 
t  From  the  discoverer,  Baldwin,  who  published  an  account  of  this  fact  in  1675. 


488  NITRATES  OF  EARTHS. 

It  is  to  be  broken  up  and  preserved  in  tight  bottles.  After  "being 
exposed  to  the  sun  for  a  few  hours,  it  emits  in  the  dark  a  beautiful 
white  light." — Henry. 

(d.)  With  a  strong  heat  it  is  completely  decomposed,  and  lime 
remains. 

(e.)  It  contains  so  much  water  that  it  scarcely  acts  on  combusti- 
bles unless  previously  dried. 

(f.)  .More  deliquescent  than  any  other  salt.* 

(g.)  Water  at  60°  dissolves  4  parts  ;  boiling  water  any  quantity ; 
and  boiling  alcohol  its  own  weight.  Although  difficult  to  crystallize, 
it  will,  when  evaporated  to  a  thickish  consistence,  often  become  solid 
and  hot  by  the  slightest  agitation. 

(h.)  J^cids,  and  alkalies  and  earths  decompose  it  in  the  same  man- 
ner as  the  other  nitrates.  If  potassa  is  added  to  a  concentrated  so- 
lution it  throws  down  the  lime  nearly  solid,  because  it  absorbs  the 
water. 

4.  PROPORTIONS. 

Exclusive  of  water,  the  equivalent  number  of  nitrate  of  lime 
would  be  82,  i.  e.  acid  54,  lime  28,  and  this  would  give  for  its  con- 
stitution in  the  100  parts, 

Acid       65.86       Mr.  Dalton  found  acid       61.3       base  38.7 

Base      34.14  Philips        "  65.6  34.4 

100.00 

The  result  of  Mr.  Philips  is  very  near  to  the  regular  constitution. 
— Id. 

NITRATE  OF  MAGNESIA. 

(a.)  Of  very  little  importance;  exists  in  the  mother  waters  of 
nitre,  and  it  may  be  formed  synthetically;  crystallizes  in  minute  nee- 
dles or  in  rhomboidal  prisms;  its  taste  is  very  bitter;  sp.  gr.  1.73; 
soluble  in  half  its  weight  of  water  at  60°,  and  in  less  at  212°;  deli- 
quescent; suffers  the  aqueous  fusion;  by  more  heat  is  decomposed, 
like  the  other  nitrates,  leaving  magnesia. 

(b.)  Emits  nitrous  fumes  with  sulphuric  acid. 

(c.)   The  alkalies  precipitate  the  magnesia. 

(d.)  Action  on  combustibles  very  feeble;  it  only  scintillates  slightly 
on  burning  charcoal. 

(e.)  Composition. — According  to  Dr.  Thomson,  acid  1  propor- 
tion, 54 ;  1  of  base  20 ;  6  of  water  54  =  128,  its  equivalent,  which  gives 
percent,  acid  42.2,  base  15.6,  water  42.2=100.0. 

*  Hence  it  is  kept  very  dry  in  close  vessels,  and  used  to  dry  the  gases  ;  being  for 
that  purpose  placed  in  tubes  through  which  they  are  made  to  pass.  Impure  deli- 
quescent nitre,  generally  contains  this  salt. 


NITRITES.  489 

NITRATE  OF  MAGNESIA  AND  AMMONIA. 

1.  PREPARATION. — Formed  by  a  partial  decomposition  of  nitrate 
of  magnesia  by  ammonia,  or  of  nitrate  of  ammonia  by  magnesia,  or 
better  by  a  mixture  of  the  two  nitrates. 

2.  PROPERTIES. 

Slender  acicular  crystals;  Utter. 

Little  deliquescent;  soluble  in  11  parts  of  water  at  60°,  in 
less  at  212°,  and  the  solution  deposits  crystals  as  it  cools.* 

NITRATE    OP  ALUMINA. 

1.  PREPARATION. — The  fresh  precipitated  earth  is  washed  and 
heated  with  dilute  nitric  acid. 

2.  PROPERTIES. 

(a.)  The  solution,  which  is  always  acid,  deposits,  after  evapora- 
tion, thin  crystalline  ductile  plates. 

(b.)  Taste  sour  and  astringent ;  extremely  soluble  and  deliques- 
cent; decomposed  by  heat  without  decomposing  the  acid. 

(c.)  Decomposed  by  most  alkalies  and  earths. 

3.  COMPOSITION. — Nitrate  of  alumina,  when  dried  between  folds 
of  blotting  paper,  is  composed  of  acid  1  proportion,  base  2,  water  10, 
and  by  a  stronger  heat  it  loses  a  portion  of  its  acid. — Thomson. 

The  nitrates  of  the  other  earths  are  unimportant. 

NITRITES. 

They  cannot  be  formed  synthetically,  and  the  only  distinct  one  is 
that  of  potassa. 

1.  PREPARATION. — Fuse  nitre  in  a  crucible  till  one  proportion  of 
its  oxygen  has  escaped,  or  partially  deflagrate  it  with  charcoal. 

2.  PROPERTIES. — Deliquescent,  and  emits  red  fumes  of  nitrous 
acid  even  with  vinegar,  and  very  strikingly  with  a  strong  acid. 

It  is  not  certain  whether  this  salt  is  a  nitrite  or  hypo-nitrite. 

RECAPITULATION 

Of  some  principal  facts  relating  to  oxygen  and  nitrogen. 
1 .  Remark. — Even  a  limited  acquaintance  with  chemistry  is  suffi- 
cient to  enable  us  to  see  that  the  properties  resulting  from  chemical 
combination  are  such  as  we  cannot  always  foresee,  nor  account  for 
when  known ;  and  that  the  different  results,  obtained  from  combina- 
tions of  the  same  elements  in  different  proportions  and  in  various  de- 
grees of  condensation,  are  very  surprising. 


*  See  Thenard,  2d  ed.  Vol.  Ill,  p.  240. 
62 


490  RECAPITULATION. 

Perhaps  the  truth  of  this  observation  is  no  where  more  manifest 
than  with  respect  to  the  bodies  composed  of  oxygen  and  nitrogen. 
These  elements  constitute  the  air  that  we  breathe,  and  also  one  of 
the  most  powerful  of  the  acids ;  they  give  us  two  other  acids  scarcely 
inferior  to  the  other  in  energy,  but  possessed  of  peculiar  and  charac- 
teristic properties ;  they  produce  also  a  gas  eminently  deadly,  and 
which,  by  acquiring  more  oxygen,  passes  instantly  to  the  condition  of 
one,  or  of  the  other  of  these  acids ;  and  finally  another  gas,  deadly 
to  animals  that  are  confined  in  it,  but  which,  when  breathed  for  a 
short  time,  by  human  beings,  is  exhilirating  beyond  any  other  agent. 
These  differences,  which  have  been  fully  unfolded  in  the  preceding 
pages,  are  attributable  solely,  so  far  as  we  know,  to  difference  of 
proportion  and  to  different  degrees  of  condensation. 

2.  Dr.  Henry,   Gay-Lussac,  Dalton,  Davy  and  Thomson,  have 
contributed  the  most  important  facts,  from  which  have  been  deduced 
the  proportions,  both  by  volume   and  weight,  of  the  compounds  of 
oxygen   and  nitrogen.     Gay-Lussac  gave  us  the  law,  to  which  no 
certain  exception  has  yet  been  ascertained ;  "that  compounds,  whose 
elements  are  gaseous,  are  constituted  either  of  equal  volumes  of  those 
elements,  or  that,  if  one  of  the  elements  exceeds  the  other,  the  ex- 
cess is  by  some  simple  multiple  of  its  volume," 

It  is  obvious  that  if  gases  sustain  this  relation  by  volume,  they  must 
sustain  a  similar  one  by  weight,  for  twice,  thrice,  &LC.  the  volume 
must  be  also  twice,  thrice,  &c.  the  weight ;  the  temperature  and 
pressure  being  the  same. 

3.  The  following  numerical  statements  exhibit  the  proportions  of 
oxygen  and  nitrogen  by  volume  and  by  weight. 

By  weight  Rep.  No.   Rep. 

for  100   Equivalent      of  the     No.  of 

Measures  of  By  weight.       parts,     proportions,  elements,     the 

nit.  ox.      nit.     ox.        nit.     ox.       nil.   ox.     nit.  ox.  cornp's 
Nitrous  oxide  contains  100     50     100-f  57     63.5836.42          +1      14-j-  8     22 
Nitric  oxide,  100  100     100     114    46.68  53.40  2      14     16     30 

Hypo-nitrous  acid,        100  150     100     171     36.81  63.20  3      14     24      38 

Nitrous  acid,  100  200     100     228     30.40  69.60  4      14     32      46 

Nitric  acid,  100  250     100     285     25.97  74.03  5      14     40      54 

It  will  be  perceived  that  the  smallest  number  in  the  first,  second,  fourth 
and  fifth  tables,  is  a  divisor  of  all  the  larger  numbers  in  that  column, 
and  that  those  other  numbers  are  of  course  multiples  of  the  smallest 
number.  Most  chemists  regard  common  air  as  a  mixture  rather  than 
a  compound ;  but  the  fact  that  it  corresponds  with  definite  propor- 
tions, both  in  volume  and  in  weight,  is  perhaps  the  strongest  argument 
that  it  is  a  compound  and  not  a  mixture,  and  perhaps  no  good  reason 
can  be  assigned  why  it  should  not  be  added  to  the  acknowledged 
compounds  of  oxygen  and  nitrogen.  See  p.  197-8. 


BORACIC  ACID.  491 

4.  It  is  thought  that  all  the  compounds  of  nitrogen  and  oxygen 
are,  essentially,  gaseous  bodies ;  the  two  oxides  are  certainly  so,  and 
can  be  combined  with  water  in  only  small  proportions.     Other  com- 
binations have  so  strong   an  affinity  for  water  that  they  have  never 
been  entirely  separated  from  it.     Nitric  acid  is  of  this  description, 
and  the  two  other  acids  unite  very  largely  with  water. 

5.  In  all  the   combinations  of  oxygen  and  nitrogen  the  elements 
are  in  a  state  of  condensation,   excepting  in  the  nitric  oxide ;  in  this 
gas,  according  to  the  opinion  of  Gay-Lussac,  the  oxygen  and  nitro- 
gen have  exactly  the  same  density  as  in  their  free  state ;  but  in  the 
other  compounds  the  condensation  is  such  that  the  oxygen  gas  does 
not  add  to  the  volume ;  or  in  other  words  the  contraction  is  equal  to 
the  volume  of  the  oxygen  gas. 

6.  As  among  gases,  the  combining  proportions  correspond  with  the 
volumes ;  the  least  volume  that  enters  into  combination  represents  the 
equivalent  or  smallest  combining   quantity.     In  the  case  of  oxygen, 
however,  as  already  stated,  the  smallest  combining  proportion  is  con- 
sidered as  corresponding  with  half  a  volume,  as  in  the  composition  of 
water. 

7.  It  is  obvious  that,   as  the  compounds  of  oxygen  and  nitrogen 
differ  from  each  other  only  in  the  proportion  of  oxygen  which  they 
contain,  they  may  be  converted  into  each  other  by  adding  or  abstract- 
ing oxygen.     This  has  been  rendered  apparent  in  the  statements  that 
have  been  already  given.     Nitric  acid,  by  its  action  on  combustibles 
and  metals,  is  often  converted  into  nitrous  acid  and  nitric  or  even  ni- 
trous oxide  ;  and  nitric  oxide,  by  the  addition  of  oxygen,  forms  the 
nitrous  acids  and  perhaps  the  nitric. 

SEC.  VI. — BORON  AND  BORACIC  ACID. 

Remark. — BORON  being  a  substance  unknown  in  common  life,  it 
will  be  most  convenient  to  describe  first,  the  acid  from  which  it  is 
obtained. 

BORACIC  ACID. 

1.  NAME  AND  DISCOVERY. — The  composition  of  this  acid  being 
unknown  when  the  nomenclature  was  formed,  it  was  therefore  named 
from  the  Borax  of  commerce,  its  parent  substance. 

The  ancient  name  of  sedative  or  narcotic  salt  was  given  to  it  by 
Homberg,  a  chemist  of  the  Academy  of  Sciences  of  Paris,  who,  in 
1702,  obtained  it  by  distilling  sulphate  of  iron  and  borax. 

2.  NATURAL  SOURCES. 

(a.)  In  the  saline  form,  borax,  from  which  chemists  always  obtain 
boracic  acid,  is  a  native  alkaline  salt,  having  soda  for  its  basis.  It 


492  BORACIC  ACID. 

is  brought  to  Europe  from  the  East  Indies,  under  the  name  of  tin- 
ea], and  is  obtained  from  Boutan  and  Thibet ;  sometimes  in  small 
crystalline  masses,  found  two  yards  under  ground  ;  it  is  procured 
also  from  natural  lakes,  whose  waters,  containing  the  salt  in  solution, 
yield  it  it  by  evaporation,  and  deposit  it  in  the  solid  form,  at  the  bot- 
tom or  in  artificial  reservoirs.  In  Europe,  the  salt  goes  through  re- 
fining processes,  formerly  confined  to  Holland  but  now  practised  in 
England. 

(6.)  In  the  free  state,  found  in  the  hot  springs  of  Lipari  and 
,  and  in  the  hot  waters  of  Lake  Cherchiago,  and  Castlenuovo, 
in  Italy.  By  evaporating  120  Ib.  of  the  water,  3  oz.  of  the  concrete 
acid  are  obtained ;  12280  grs.  of  the  water  of  Lake  Castlenuovo 
yielded  120  grains  of  acid. 

Boracic  acid  is  also  found  in  the  vicinity  of  these  lakes,  adhering  to 
the  rocks  in  crystals. 

The  boracic  acid  is  now  obtained  in  such  quantities  from  Tuscany 
that  it  forms  an  important  article  of  commerce,  and  is  used  to  form 
borax  by  a  direct  combination  with  soda. 

(c.)  In  minerals.  Found  in  the  Boracite  of  Luneberg,  a  hard 
cubical  stone,  imbedded  in  gypsum,  and  containing  magnesia  as  the 
basis  ;  also  in  the  Datholite  and  in  Tourmalines,  &c. 

3.  PREPARATION. — Obtained  from  borax,  both  by  sublimation 
and  by  precipitation. 

(a.)  By  sublimation.  A  solution  of  2  Ibs.  calcined  sulphate  of 
iton,  and  2  oz.  of  borax,  is  filtered,  evaporated  to  a  pellicle,  and  sub- 
limed in  an  alembic  or  retort ;  the  boracic  acid,  in  crystals,  lines  the 
upper  cavity,  and  may  be  swept  out  with  a  feather.* 

(b.)  Or,  the  acid  may  be  obtained  of  a  beautiful  whiteness,  by  ad- 
ding to  the  borate  of  soda  J  its  weight  of  sulphuric  acid,  and  sub- 
liming.^ 

(c*)  The  usual  process  is  to  dissolve  borax  2  parts,  in  water  6 
or  8;  and  to  add  Ij  of  sulphuric  acid  diluted  with  1  of  water,  a  gen- 
tle heat  being  continued  for  a  short  time ;  it  is  set  by,  and  on  cool- 
ing, crystals  of  boracic  acid,  in  white  shining  plates  or  scales,  or  mi- 
nute prisms,  will  be  abundantly  precipitated.  They  must  be  washed 
with  cold  distilled  water,  to  remove  any  adhering  sulphuric  acid,  or 
sulphate  of  soda,  and  dried  on  blotting  paper.  The  remaining  fluid 
is  a  solution  of  sulphate  of  soda.  The  crystals  obtained  in  this  man- 
ner are  still  contaminated  by  a  little  of  the  base  of  the  borax,  and  of 
the  acid  used  to  decompose  it.  It  is  said  to  be  obtained  purer  by 
using  the  muriatic  or  the  nitric  acid,  instead  of  the  sulphuric.  Gay- 


*  Chaptal,  Vol.  I,  p.  265. 

t  The  product  by  sublimation  is  much  less  than  by  precipitation — Id. 


BORACIC  ACID,  493 

Lussae  prefers  the  muriatic,  and  the  boracic  acid  must  be  afterwards 
ignited  in  a  platinum  crucible,  to  expel  any  excess  of  the  decompos- 
ing acid. 

4.  PROPERTIES. 

(a.)   The  form  is  that  ofkexahedral  scales,  white  and  brilliant. 

(b.)  Feel,  a  little  unctuous,  like  spermaceti,  which  it  somewhat  re- 
sembles. The  sublimed  boracic  acid  is  much  more  light  and  volu- 
minous than  the  precipitated. 

!c.)   Taste,  cool,  bitterish,  and  slightly  sour;  inodorous, 
d.)  Reddens  blue  vegetable  colors,  effervesces  with  the  alkaline 
carbonates,  but  turns  turmeric  brown,  like  the  alkalies.     Its  sp.  gr. 
1 .48— after  fusion,  1.803. 

(e.)  "  When  sulphuric  acid  is  poured  upon  it,  a  transient  odor  of 
musk  is  produced." 

(/.)  This  acid  a  hydrate,  for  by  ignition  it  loses  about  43  per  cent, 
which  is  the  water  of  crystallization;  if  heat  be  suddenly  applied,  a 
large  quantity  of  acid  rises  with  the  water  of  crystallization,  and  in 
either  case  we  obtain  boracic  acid,  fused,  and  becoming  when 
cold,  a  hard  transparent  glass,  not  deliquescent,  but  partly  opaque  ; 
if  dissolved  in  hot  water,  it  crystallizes  again  on  cooling.  Authors 
are  exceedingly  at  variance  as  regards  the  solubility  of  this  acid  ; 
but  they  agree  that  it  is  much  more  soluble  in  hot  than  in  cold 
water,  the  general  statement  being  12  parts  of  cold,  and  3  or  4  of 
boiling  water.* 

(g.)  When  a  saturated  solution  of  this  acid,  in  water,  is  distilled, 
a  part  of  the  acid  passes  over,  and  crystallizes  in  the  receiver  ;  when 
solid,  it  will  melt  into  glass,  rather  than  sublime. 

(h.)  Soluble  in  5  parts  of  boiling  alcohol,  which  will  then  burn 
with  a  beautiful  green  flame ;  it  is  best  exhibited  by  dipping  a  paper 
in  the  solution,  and  setting  it  on  fire,  or  by  burning  it  from  a  watch 
or  wine  glass ;  but  sponge  does  not  shew  it  well,  as  the  yellow  color 
produced  by  the  salt  with  which  it  is  impregnated,  overpowers  the 
green.  If  the  paper  which  has  been  dipped  in  the  alcoholic  solution 
be  dried  first,  it  then  burns  with  a  yellow  flame ;  other  substances, 
which  burn  with  a  blue  flame,  as  sulphur,  burn  green  when  mixed 
with  boracic  acid.f 

5.  COMPOSITION  AND  POLARITY. — In  the  next  article,  the  de- 
composition of  this  acid  will  be  mentioned ;  we  may  now  say  that  it 
has  a  combustible  base,  called  boron,  which  by  union  with  oxygen, 
forms  boracic  acid. 


*  According  to  Murray  it  requires  5  parts  of  boiling  water,  and  2&  of  cold  ;  but 
Davy  asserts  that  it  requires  50  parts,  even  of  boiling  water, 
t  Aikin'sDict. 


494  BORACIC  ACID. 

Boron  1  proportion,  represented  by  the  same  number  as  oxygen, 
namely  8,  -{-2 prop,  oxygen  1 6,  forms  dry  boracic  acid,  having  24 
for  its  equivalent ;  the  crystallized  acid  consists  of  dry  acid  24  -j- 
water  2  proportions,  18 =42  for  the  equivalent  of  the  crystallized 
acid;  and  for  the  100  parts,  42  :  18  :  :  100  :  43  nearly,  being  the 
quantity  of  water  in  the  100  parts,  of  course  there  is  57  of  dry  acid. 
According  to  Berzelius,  crystallized  boracic  acid,  contains  .44  of 
water,  one  half  of  which  is  expelled  at  a  heat  above  212°,  and  the 
other  half  when  it  combines  with  bases,  but  it  cannot  all  be  expelled 
by  heat  alone, 

6,  POLARITY. — In  the  galvanic  circuit,  this  acid  goes  to  the  posi- 
tive pole,  and  is  therefore,  electro  negative. 

7.  USES. — It  melts  very  easily,  and  by  acting  as  a  flux,  it  favors 
the  fusion  of  minerals,  with  the  blow  pipe.     It  is  used  in  the  analysis 
of  stones,  aiding  their  fusion  in  the  crucible.     After  it  is  melted  by 
itself,  it  endures  a  white  heat  without  volatilization,  and  as  it  cools 
into  a  glass,  it  is  called  a  glacial  acid,  being  one  of  three  that  bear 
that  name,  viz.  the  phosphoric,  the  arsenical,  and  the  boracic. 

In  the  dry  way,  viz.  with  heat,  the  boracic  acid  displaces  all  the 
acids  except  the  phosphoric  ;  this  arises  from  its  great  fixity  and  fusi- 
bility by  which  it  is  able  to  vitrify  the  bases  of  the  salts,  even  of  the 
earthy  salts. 

BORON. 
DECOMPOSITION  OF  BORACIC  ACID. 

1.  DISCOVERY  OF  BORON. 

(a.)  The  power  of  500  pairs  of  galvanic  plates  extricates  from 
moistened  boracic  acid  a  peculiar  olive  colored  combustible  basis,  first 
ascertained  by  Davy,  in  1807. 

2.  PROCESS. 

(a.)  Better  obtained  by  heating  very  pure  vitreous  boracic  acid 
along  with  potassium,  in  tubes  of  green  glass  or  copper,  iron  or 
brass  ;  preferably  the  last. 

(b.)  12  or  14  grains  of  each  substance  were  employed  ;  but  8  grains 
of  boracic  acid  will  saturate  20  grains  of  potassium.  At  302°  Fahr. 
ignition  comes  on,  a  little  hydrogen  appears,  the  potassium  is  con- 
verted into  potassa,*  and  boron  is  obtained. 


*  See  Recherches  Physico-Chimiques,  Vol.  I.  Berzelius  employs  the  fluo-borate 
of  potassa  with  potassium  in  a  crucible  ;  the  boron  is  to  be  washed  with  sal-ammoniac, 
and  lastly  with  alcohol ;  as  water  carries  some  of  it  through  the  filter.  This  process 
is  said  to  be  less  expensive  in  potassium  than  the  other. 


BORACIC  ACID.  495 

3.  PROPERTIES. 

(a.)  An  opake,  pulverulent,  olive  colored  mass,  does  not  scratch 
glass,  does  not  conduct  electricity,  is  tasteless,  inodorous,  insoluble  in 
water,  ether,  alcohol  and  oils,  and  does  not  affect  blue  colors. 

(b.)  Burns  in  atmospheric  air,  at  a  heat  below  that  of  boiling 
olive  oil,  or  at  about  600°,  with  a  red  light,  sparkles  like  charcoal, 
and  produces  boracic  acid,  the  coating  of  which,  on  the  boron,  soon 
stops  the  combustion. 

(c.)  Not  fused  or  volatilized  by  a  white  heat,  in  close  vessels,  but 
becomes  dense  enough  to  sink  in  sulphuric  acid  of  the  sp.  gr.  1.844, 
hence  its  sp.  gr.  must  be  nearly  2. 

(d.)  The  heat  of  a  spirit  lamp  makes  it  burn  brilliantly  in  oxygen 
gas,  and  boracic  acid  sublimes.* 

(e.)  It  burns  spontaneously  in  chlorine  gas,  and  forms  a  new  gas, 
which  when  brought  into  contact  with  atmospheric  air,  smokes  as 
much  as  fluoboric  gas.  Freed  from  excess  of  chlorine,  by  standing 
over  mercury  it  becomes  colorless,  and  is  rapidly  absorbed  by  water ; 
its  composition  is  chlorine,  90.743,  boron,  9.257  =  100. — Berzelius. 

(jf.)  Niti'ic  acid  converts  it  into  boracic  acid,  while  nitric  oxide 
gas  is  liberated. 

(g.)  It  dissolves  in  hot  sulphuric  acid  with  effervescence,  and  pot- 
ash throws  down  a  black  precipitate. 

(h.)  Muriatic  acid  acquires  a  green  color,  but  its  action  is  feeble, 
and  there  is  no  solution. 

(i.)  With  fixed  alkalies,  it  forms  pale  olive-colored  compounds, 
from  which  muriatic  acid  throws  down  dark  precipitates. 

(j.)  Sulphur  dissolves  it  by  long  fusion,  and  acquires  an  olive  tint 
— little  action  with  phosphorus,  none  with  mercury. 

(k.)  It  burns  vividly,  when  mixed  with  chlorate  or  nitrate  of  potash, 
and  thrown  into  a  red  hot  crucible. 

(I.)  Boron  heated  in  the  vapor  of  sulphur,  unites  with  it,  with  the 
appearance  of  combustion — producing  a  sulphuret,  which  is  white  and 
opake,  and  which,  when  thrown  into  water,  gives  off  sulphuretted 
hydrogen  and  forms  boracic  acid. 

4.  EQUIVALENT  NUMBER  AND  POLARITY. 

The  equivalent  of  boron  is  8,  as  already  stated.  In  the  galvanic 
circuit,  it  goes  to  the  negative  pole. 

5.  NATIVE  BORON. 

Boron  is  to  be  regarded  as  a  peculiar  combustible  ;  a  little  resem- 
bling carbon  in  fixity  in  the  fire,  but  it  is  unlike  it  in  being  a  non-con- 
ductor of  electricity. 


*  There  is  a  black  residuum  which  produces  more  boracic  acid  by  being  heated 
again  in  oxygen  gas. 


496  BORATES. 

BORATES  OF  ALKALIES  AND  EARTHS. 

General  properties, 

1.  In  the  humid  way,  decomposed  by  all  acids  except  the  car- 
bonic. 

2.  In  the  dry  way,  the  action  is  often  reversed,  especially  where 
the  acid  of  the  other  body  has  a  tendency  to  become  gaseous. 

3.  Boracic  acid  attracts  the  earths  more  forcibly  than  the  alkalies. 

4.  Alkaline  borates  are  very  soluble  in  water  ;  the  earthy  the  re- 
verse. 

5.  The  boracic  acid  being  feeble,  it  neutralizes  the  alkaline  bases 
imperfectly,  and  hence  the  borates  of  the  alkalies  have  alkaline  char- 
acters. 

6.  Borates  are  very  fusible. 

7.  Digested  with  strong  sulphuric  acid,  the  residue  imparts  to  al- 
cohol the  power  of  burning  with  a  green  flame. 

BORATE  OF  POTASSA. 

1.  PROCESS. 

(a.)  Boil  boracic  acid  in  caustic  potash,  either  to  saturation  or  so 
as  to  leave  a  slight  excess  of  alkali. 

(b.)  In  the  latter  case,  it  crystallizes  in  pretty  large  four  sided 
prisms — taste  sub-alkaline. 

2.  PROPERTIES. 

(a.)  Not  altered  by  the  air — by  heat,  swells,  foams,  and  runs  into 
a  clear  glass. 

(6.)  Decomposed  by  lime,  baryta,  and  magnesia. 

BORAX. 

BI-BORATE  OF  SODA,  formerly  called  sub-borate. 

1.  PREPARATION. — It  can  be  formed  synthetically,  but  this  is  un- 
necessary, as  it  is  abundant  in  commerce. 

2.  PROPERTIES. 

(a.)  Turns  vegetable  blues  green;  taste,  cool,  sweetish,  and  sub- 
alkaline. 

(b.)  Soluble  in  12*  parts  of  cold  water,  and  in  6  of  boiling  ;  slight- 
ly efflorescent ;  deposits  crystals  by  cooling ;  prisms  with  6  irregular 
sides.  Phosphoresces  by  collision  of  its  crystals. 

(c.)  Suffers  the  aqueous  fusion,  is  very  much  inflated,  and  at  igni- 
tion becomes  a  pellucid  glass  ;  soluble  again  in  water. f 


t  Provided  it  were  melted  in  a  silver  crucible  or  hastily  in  one  of  earth,  for  it  H 
prone  to  corrode  earthen  crucibles. 


BORATES.  497 

(d.)  Sp.  gr.  1.74 — after  fusion,  flies  and  cracks  to  pieces  in 
cooling. 

(e.)  Action  of  the  acids  as  already  mentioned  under  boracic  acid, 
and  the  general  characters  of  the  borates. 

(/.)  If  only  the  excess  of  soda  be  neutralized  by  an  acid,  the  whole, 
by  evaporation  becomes  a  confusedly  crystallized  mass,  containing  all 
the  ingredients. 

(g.)  The  excess  of  alkali  can  also  be  saturated  by  boracic  acid;  the 
salt  takes  up  nearly  half  its  weight,  and  ceases  to  affect  the  blue  col- 
ors, to  effloresce,  to  taste  alkaline,  and  to  crystallize  in  the  same  form 
as  borax. 

(h.)  Baryta,  strontia,  lime,  and  magnesia,  decompose  borax. 

(i.)  Potash  also  decomposes  it,  but  there  is  no  precipitate,  because 
soda  dissolves  borate  of  potash. 

(j.)  Borax  fluxes  silica  into  a  transparent,  and  alumina  into  an 
opake  glass  ;  the  ingredients  being  in  equal  proportions,  the  com- 
pound is  insoluble  in  the  mineral  acids,  but  a  great  excess  of  borax 
makes  it  soluble. 

(k.)  The  borax  of  the  shops  exhibits  an  imperfect  crystallization, 
with  a  figure  approaching  to  the  hexahedral  prism.  The  crystals 
are  slightly  efflorescent. 

3.  COMPOSITION  AND  REPRESENTATIVE  NUMBER. 

Gmelin,    acid,  35.60,    base,  17.80,    water,  46.6  =  100  )         , 

Thomson,          31.51,  20.42,  48.0=100  j n< 

The  representative  number  of  boracic  acid  has  already  been  stated 
as  being  24.     According  to  Dr.  Thomson,  this  salt  is  composed  of 
2  proportions  of  boracic  acid,  =48 

1         "  soda,        -  -    =32 

8         "  water,  -         -         -          =72 


Its  equivalent,       152 
In  the  100  parts,  acid  31.58,  soda  21.05,  water  47.37. 

4.  MISCELLANEOUS. — The  natural  and  commercial-  history  of  this 
salt  has  been  already  given  under  boracic  acid.  In  addition  to  the 
localities  already  named,  it  is  found  in  China,  in  Peru,  in  Transyl- 
vania and  Saxony.* 

The  crude  borax  brought  from  the  East  Indies  and  the  Levant,  is  al- 
ways enveloped  in  an  oleaginous  matter  ;  which  Vauquelin  found  to  be 
a  soap  with  soda  for  its  base.  It  is  believed  that  the  natives  cover  it 
with  a  film  of  oil  to  prevent  its  efflorescence,  and  it  is  said  to  be  mois- 
tened by  sour  milk  for  the  same  purpose. 

It  is  purified  by  repeated  solutions  and  crystallizations,  in  vessels  of 
lead  ;  they  obtain  from  the  tincal  .80  of  borax,  and  they  expose  it 

*  Thenard,  III,  90. 
63 


498  BORATES. 

to  heat  as  a  preparatory  operation,  to  burn  off  the  oily  or  fatty  matter 
which  surrounds  it.  Formerly  the  manufacture  was  confined  to 
Holland,  and  it  seems  not  to  have  been  known  that  an  addition  of 
soda  was  necessary  to  saturate  the  boracic  acid. 

Borax  is  now  abundantly  manufactured  in  France,  by  the  combi- 
nation of  the  boracic  acid,  obtained  from  Tuscany,  with  soda;  the 
French  consume,  annually,  about  25  tons,  and  they  no  longer  import 
the  tincal. 

In  forming  borax  in  France,  they  dissolve  1200  Ibs.  of  carbonate 
of  soda  in  1000  Ibs.  of  water,  and  add,  by  20  Ibs.  at  a  time,  600  Ibs. 
of  Tuscan  boracic  acid  ;  the  processes  are  conducted  in  leaden  boil- 
ers, by  repeated  solutions  and  crystallizations,  and  many  circumstan- 
ces must  be  attended  to  in  order  to  obtain  large  and  handsome  crys- 
tals. 100  Ibs.  of  the  best  Tuscan  boracic  acid,  containing  about 
half  its  weight  of  the  pure  acid,  produce  about  150  of  refined  bo- 
rax ;  but  as  the  acid  is  not  always  pure  and  there  is  some  loss  in  the 
processes,  the  product  is  ordinarily  not  more  than  140  or  142  Ibs.  of 
borax  from  100  of  boracic  acid.* 

5.  USES.— Formerly  used  internally  as  a  sedative,  and  still  employ- 
ed to  form  a  gargle  to  remove  the  aphthous  crust  from  the  mouths  of 
children  ;  it  is  a  flux  for  the  blowpipe ;  for  the  vitreous  materials  of 
artificial  gems  or  pastes,  and  for  the  glazing  of  porcelain.  Known 
from  remote  antiquity,  and  it  is  mentioned  by  Pliny  as  chrysocolla  or 
gold  glue,  in  allusion  to  its  use  in  soldering  the  precious  metals ; 
from  which  it  removes  impurities,  preventing  also  oxidation. 

BORATE  OF  AMMONIA. 

1.  PROCESS. — By  digesting  boracic  acid  with  ammonia,  we  obtain 
small  rhomboidal  octahedra. 

2.  PROPERTIES. 

(a.)  Taste  sharp ;  turns  the  blue  vegetable  test  liquors  green ; 
undergo  slight  efflorescence  in  the  air. 

(b.)  The  ammonia  is  expelled  by  heat  and  the  boracic  acid  is  left; 
according  to  Lassone,f  the  entire  salt  melts  into  a  grayish  glass,  and 
gives  after  solution,  the  same  crystals  as  before. 

(c.)  Decomposed  by  the  fixed  alkalies  both  in  the  moist  and  dry 
way, 

BORATE  OF  BARYTA. 

Add  boracic  acid  to  barytic  water,  and  a  white,  insipid,  insoluble 
powder  precipitates. 

BORATE  OF  STRONT1A. 

1.  Same  mode  of  formation  ;  a  copious  precipitate. 

2.  Prone  to  an  excess  of  base;  soluble  in   130  parts  of  boiling 
\vater,  and  is  scarcely  affected  by  cold  water. 

*  Gray's  Op.  Chem.  p.  526.  t  Aikin,  Vol.  I,  p.  156. 


FLUORIC  ACID.  499 

BORATE  OF  LIME. 

1.  PROCESS. — Mix  boracic  acid  or  borax  with  lime  water,  or  any 
soluble  salt  of  lime. 

2.  PROPERTIES. 

(a.)  A  white,  insoluble,  insipid  powder ;  fusible  at  ignition. 

(b.)  Chalk  2,  and  boracic  acid  1,  at  ignition,  produce  a  yellow 
glass  so  hard  as  to  strike  fire  ;  with  the  reverse  proportions,  the  mat- 
ter often  runs  through  the  crucible. 

BORATE   OF  MAGNESIA. 

1.  PROCESS. — By  long  digestion  of  boracic  acid  with  magnesia; 
or  a  mixture  of  any  soluble  borate  with  any  soluble  magnesian  salt, 
produces  this  combination. 

2.  PROPERTIES. — An  insoluble  and  insipid  precipitate,  without 
any  crystalline  form ;  fusible,  at  ignition,  into  a  white  semi-transpa- 
rent glass. 

The  bi-borate  of  magnesia  is  found  native  at  Luneberg,  Germany, 
under  the  name  of  the  boracite  ;  it  is  in  small  cubical  crystals,  often 
highly  modified. 

BORATE  OF  ALUMINA. 

1.  Newly  precipitated  and  undried  alumina  is  digested  with  bo- 
racic acid. 

2.  Evaporation  gives  a  viscid  mass,  through  which  minute  crystals 
are  interspersed  ;  taste  astringent. 

SEC.  VII. — FLUORIC  ACID. 

Remark. — In  order  to  entitle  the  fluoric  acid  to  a  place  here,  strict 
method  would  require  that  a  combustible  basis  should  have  been  prov- 
ed to  exist  in  this  acid,  and  that  this  base  should  be  described  in  con- 
nexion with  the  acid.  But  as  we  have  no  decisive  proof  as  to  the 
nature  of  the  fluoric  radical,  the  present  arrangement  can  be  consid- 
ered as  provisional  only ;  for  it  remains  yet  to  be  seen  whether  fluo- 
ric acid  is  composed  of  a  combustible  basis  and  oxygen,  or  of  a 
peculiar  principle,  analogous  to  iodine  and  chlorine,  and  hydrogen, 
or  whether  it  has  a  composition  entirely  peculiar ;  for  all  analogy 
leads  to  the  opinion  that  it  is  compound. 

1.  HISTORY. — Re-discovered  by  Scheele,  A.  D.  1771  ;*  for  it  ap- 
pears to  have  been  first  obtained  (A.  D.  1670,)  by  the  artist  Shank- 
hard,  at  Nuremburg;  and  also  by  Pauli,  at  Dresden,  A.  D.  1725, 
who  employed  it,  as  Shankhard  had  done,  to  corrode  glass,  but 


Vide  Scheele's  Essays,  Vol.  I. 


500  FLUORIC  ACID. 

the  subject  was  forgotten,  till  Mr.  Scheele  revived  it.  The  acid  of 
Scheele  was,  however,  impure,  and  it  was  not  till  Gay-Lussac  and 
Thenard  obtained  it,*  that  it  was  known  in  purity. 

2.  ORIGIN  AND  NAME. — Exists  abundantly  in  the  beautiful  mine- 
ral called  Derbyshire  spar ;  it  being  found  in  great  quantities  in  tha.t 
county,  in  England.     This  mineral  is  called  also  fluor,  or  fluor  spar, 
because,  being  fusible,  it  is  used  as  a  flux  for  ores.     It  is  usually 
crystallized  in  cubes,  with  an  octahedral  nucleus,  which  gives,  by  con- 
tinued dissection,  octahedra  and  tetrahedra.     When  pure,  it  is  white, 
but  it  is  most  commonly  colored. 

Jls  the  fluor  spar  affords  the  acid  in  question,  the  name,  fluoric 
acid,  was  bestowed,  because  the  composition  was  then,  as  it  is  still,  un- 
known. 

3.  PREPARATION. 

(a.)  Gay-Lussac  and  Thenard  employed  a  leaden  cylinder,  con- 
nected by  a  recurved  leaden  tube,  with  another  leaden  vessel  for  a  re- 
ceiver ;  the  latter  was  kept  cold  by  ice. 

(b.)  Finding  lead  so  liable  to  fusion,  I  have  used  a  silver  alembic, 
with  a  capacity  of  16  fluid  ounces,  its  head  and  tube  2j,  and  the  tube 
fitted  tight  to  a  silver  bottle  of  3J  oz.  the  latter  furnished  with  a 
ground  silver  stopper,  to  preserve  the  acid,  and  to  save  the  necessity 
of  pouring  it  into  another  vessel. 

(c.)  In  the  alembic  are  placed  2  oz.  of  pure  fluor  spar,  and  4  oz. 
of  strong  sulphuric  acid ;  the  receiver  is  surrounded  by  ice  or  snow, 
and  a  few  live  coals  are  placed  beneath  the  alembic,  whose  head  is 
made  securely  tight  by  a  lute  of  finely  powdered  pipe  clay,  placed  in 
the  joint,  and  a  rag,  smeared  with  the  same,  is  bound  tightly  over  it. 
The  receiver  should  not  be  pressed  hard  home,  so  as  to  be  accurate- 
ly tight  upon  the  tube,  but  a  little  room  should  be  left  for  the  escape 
of  the  vapor  of  the  acid. 

(d.)  The  apparatus  should  be  under  a  well  drawing  flue,  the  hands 
protected  by  thick  gloves,  and  the  receiver,  when  moved,  should  be 
grasped  by  small  tongs,  furnished  with  curvatures,  to  fit  the  neck  of 
the  bottle. f  In  about  half  an  hour,  the  process  will  be  through,  and 

*  Recher.  Phy.-Chim.  Vol.  II. 

t  As  represented  in  the  annexed  figures,  which  being  made  with  corresponding 

c==o  «=-°°~ 


flexions,  and  of  various  sizes,  from  those  that  are  very  delicate  and  adapted  to  sustain 
the  minutest  flasks  by  the  neck,  to  such  as  will  lift  a  heavy  crucible,  or  a  basin,  are 
highly  convenient. 


FLUORIC  ACID.  501 

on  shaking  the  bottle,  the  movement  of  the  liquid  fluoric  acid  will 
be  distinctly  perceived.* 

4.  PROPERTIES. 

(a.)  An  exceedingly  volatile  fluid;  extremely  corrosive,  suffoca- 
ting',  and  dangerous. 

(b.)  Jit  32°  Fahr.  it  is  a  colorless  fluid.  Sp.  gr.  1.0609,  and  by 
gradual  additions  of  water,  its  density  is  increased  to  1.25.f 

(c.)  Retains  its  liquid  form  at  60°,  if  preserved  in  well  stopped 
silver  bottles  :J  those  of  lead  answer  but  imperfectly,  as  the  acid  cor- 
rods  them  and  escapes. 

Sd.)  Does  not  congeal  at  —4°  Fahr. 
e.)   When  strong,  emits  into  the  air  dense  white  fumes,  which  evi- 
dently arise  from  a  combination  with  the  watery  vapor. 

(f.)  Potassium  burns,  or  rather  detonates  in  the  liquid  fluoric 
acid ;  hydrogen  gas  is  disengaged,  and  a  solid  white  substance  is 
formed.  This  experiment  must  be  performed  in  a  metallic  vessel ; 
a  platinum  crucible  or  capsule  answers  well. 

(§•.)  Dropped  into  water,  it  hisses  like  a  hot  iron,  and  there  is 
great  agitation,  and  even  ebullition,  especially  when  water  is  added  to 
the  acid. 


*  See  Am.  Jour.  Vol.  XVI,  p.  354. 

With  the  proportion  of  acid  mentioned  in  the  text,  (that  of  Gay-Lussac  and  The- 
nard,)  the  silver  alembic  is  sometimes  attacked,  and  corroded  through  and  through, 
as  I  have  more  than  once  experienced.  If  we  diminish  the  quantity  of  acid,  using 
3  to  2  of  fluor,  or  even  equal  weights,  the  danger  to  the  vessel  is  much  diminish- 
ed, but  the  product  of  fluoric  acid  is  less,  and  the  residuum  in  the  alembic  is  much 
more  difficult  to  remove.  To  a  certain  extent,  the  smaller  the  proportion  of  sulphu- 
ric acid  used,  the  stronger  and  more  fuming  is  the  fluoric  acid  obtained.  A  similar 
effect  is  produced  by  previously  heating  the  sulphuric  acid,  for  some  time,  near  to  its 
boiling  point.  The  reason  is  obvious ;  it  is  the  water  of  the  sulphuric  acid  that 
serves  to  condense  the  fluoric  acid,  otherwise  incoercible,  at  least  at  the  tempera- 
ture of  ice,  and  under  the  ordinary  pressure,  and  therefore,  the  less  in  quantity, 
and  the  stronger  the  sulphuric  acid,  (provided  it  is  sufficient  for  the  decomposition,) 
the  more  concentrated  will  be  the  fluoric  acid.  I  have  known  the  latter  so  active 
as  to  be  of  very  difficult  condensation  ;  blowing  out  the  silver  ground  stopper  with 
violent  puffs,  and  rapidly  wasting  away  by  its  own  evaporation.  A  little  water  in 
the  receiver,  however,  prevents  this,  and  if  our  object  is  to  etch  on  glass,  a  diluted 
acid  is  much  preferable.  The  strong  acid  of  Gay-Lussac  is  needed  only  to  display 
its  own  dangerous  and  wonderful  energy,  and  too  much  caution  cannot  be  recom- 
mended to  those  who  prepare  it. 

t  This  is  said  to  be  unlike  other  fluids,  but  is  it  however,  really  an  exception  ? 
Alcohol  and  water,  and  sulphuric  acid  and  water,  acquire  by  union,  a  gravity  great- 
er than  the  mean.  This  acid  appears  to  attract  water  with  more  energy  than  the 
sulphuric,  much  more  heat  is  evolved  by  the  condensation,  and  the  density  ought 
to  be  increased  considerably. 

t  In  silver  bottles,  with  well  ground  stoppers,  in  a  cellar,  it  can'be  kept  the 
year  round;  but  from  lead  bottles,  however  well  ground  and  luted,  it  almost  always 
makes  its  escape,  corroding  the  lead ;  and  glass  vessels  in  the  vicinity  are  extensive- 
ly covered  with  a  white  deposit  of  silica,  rendering  them  opake.  This  eeffct  men- 
tioned by  Dr.  Thomson,  (First  Principles,  Vol.  II,  p.  165.)  I  have  often  seen. 


502  FLUO-SILICIC  ACID. 

(A.)  Respiration.  The  vapor  is  extremely  dangerous  in  the 
lungs  ;  and  should  be  anxiously  avoided. 

(i.)  Contact  with  the  body.  This  also  is  dangerous  ;  excepting 
prussic  acid,  there  is  perhaps  no  agent  so  deleterious.  It  instantly 
disorganises  the  skin ;  painful  and  obstinate  ulcers  are  formed,  for 
it  seems  to  penetrate  into  the  very  tissue  of  the  parts  ;  there  is  a 
general  irritation  of  the  system,  and  sometimes  extirpation  of  the  in- 
jured portion  is  the  only  remedy.  Even  contact  with  the  vapors 
floating  about  should  be  avoided,  for  they  immediately  irritate  the 
skin,  and  may  produce  permanent  injury.  J 

(j.)  Fluoric  acid,  largely  diluted  in  vessels  of  lead,  platinum  or 
silver,  has  a  decidedly  acid  taste,  and  reddens  the  vegetable  blues. 

(&.)  It  forms  salts  with  the  salifiable  bases  ;  "  and  with  acids  weak- 
er than  itself,  it  produces  compounds,  in  which  the  latter  serve  as  a 
kind  of  base."  By  dilution  with  water,  these  acids  suffer  a  partial 
decomposition,  and  deposit  a  portion  of  their  base  ;  of  this  description 
are  fluo-boric,  and  fluo-silicic  acids,  which  will  be  described  in  then 
places. 

(/.)  The  constitution  and  combining  weight  of  fluoric  acid  will  be 
mentioned  at  the  conclusion  of  the  whole  subject. 

FLUO-SILICIC  ACID  GAS. 

The  action  of  fluoric  acid  upon  silica  is  so  peculiar,  as  to  merit  a 
distinct  consideration. 

The  strong  acid  ofGay-Lussac  instantly  soils  glass  ;  attacking  it  with 
as  much  energy  as  sulphuric  acid  does  an  alkali ;  heat  is  evolved,  and 
instead  of  having  its  volatility  diminished,  it  becomes,  by  this  union, 
permanently  aeriform  ;  a  true  gas  ;  although  before  only  a  vapor. 

1.  PREPARATION. 

(a.)  This  gas  is  of  course  produced,  whenever  the  ordinary  process 
for  fluoric  acid  is  performed  in  glass  vessels,  but  it  is  usual  to  add  half 
as  much  pulverized  glass  asfluor  spar  to  the  mixture  of  equal  parts  of 
the  latter,  and  strong  sulphuric  acid. 

(b.)  In  the  latter  case,  the  glass  retort  will  be  much  less  corroded, 
but  in  my  experiments  it  has  always  been  attacked  in  some  degree, , 


I  Gay-Lussac  and  Thenard  mention  (Recher.-Phys.  Chim.  Tom.  II,  p.  11,)  that 
some  of  their  assistants  suffered  severely  for  a  month,  from  exposure  for  a  few  min- 
utes to  the  acid  vapor,  coming  in  contact  with  the  fore  finger  and  thumb ;  and  a  dog 
upon  whose  back,  deprived  of  hair  at  that  place,  six  drops  of  this  acid  were  allowed 
to  fall,  suffered  extremely,  and  in  a  few  hours  died  in  agony.  They  state  that  the 
effect  is  not  always  perceived  till  7  or  8  hours  after  the  contact  of  the  vapor,  and 
that  even  when  it  is  too  feeble  to  be  observed,  it  produces  in  a  few  hours,  acute 
pain,  loss  of  sleep,  and  fever.  Similar  results  have  several  times  been  observed  in 
my  laboratory. 


FLUO-SILIC1C  ACID.  503 

and  if  not  protected  by  the  mixture  of  glass,  it  is  usually  eaten  through 
and  through. 

(c.)  Even  with  the  addition  of  glass,  I  have  never  failed  to  find  the 
vessels  covered  by  an  opake  white  crust  of  silica,*  less  remarkable 
however  than  when  the  fluor  and  sulphuric  acid  alone  are  mingled, 

2.  PROPERTIES. 

(a.)  Received  over  mercury,  it  is  a  gas,  colorless  and  invisible  ; 
it  extinguishes  a  burning  candle,  but  shows  a  blue  border  surround- 
ing the  red  flame ;  it  smokes  in  the  air,  producing  a  dense  fog  like 
muriatic  acid  gas,  which,  in  odor,  it  strongly  resembles  ;  the  cloud  is 
produced  by  the  combination  of  the  acid  gas  with  the  atmospheric  wa- 
ter, silica  being  at  the  same  time  deposited,  in  a  state  of  minute  di- 
vision. 

(b.)  It  is  fatal  to  animals  confined  in  it,  and  is  suffocating  to  the 
experimenter;  but  its  properties  are  so  repressed  by  combination 
with  the  silica,  that  it  is  not  particularly  dangerous  to  inhale  a  little  of 
it  mixed  with  the  air  of  the  room. 

(c.)  Sp.gr.  3.6111,  air  being  1,  and  100  cubic  inches  at  60°  Fahr. 
and  30  inches  barometer,  weigh  110.138  grains. — Thomson. 

(d.)  Dr.  John  Davy,  by  decomposing  it  by  liquid  ammonia,  found 
that  61.4  of  the  weight  of  the  gas  is  silica.  Dr.  Thomson,  from  40 
cubic  inches  of  the  gas  (=44.05  grains,)  obtained  27.14  silica,  which 
is  at  the  rate  of  61.60  per  cent.  It  is  indeed  most  singular,  that  a 
very  volatile  vapor,  by  corroding  siliceous  bodies  and  becoming  charg- 
ed with  more  than  60  per  cent,  of  a  naturally  very  Jixed  and  almost 
unalterable  earth,  should  become  a  gas,  which,  when  dry,  is  perma- 
nent. 

(e.)  Water.  This  fluid  absorbs  about  263  times  its  volume  of 'this 
gas,  and  the  solution  does  not  corrode  glass  vessels.  During  the  so- 
lution, one  third  of  the  silica  is  deposited,  and  the  remainder  with  the 
fluoric  acid  is  retained  in  the  water,  and  was  called  by  Dr.  Davy, 
sub-silicated  fluoric  acid.  It  is  sour  and  reddens  litmus. 

(/.)  The  precipitate  is  a  gelatinous  hydrate  of  silica,  and  after  be- 
ing washed  and  ignited,  it  is  regarded  by  Berzelius  as  pure.  It  af- 
fords perhaps  the  easiest  method  of  obtaining  that  earth. 

(<§"•)  Silicated  fluoric  acid  gas,  when  passing  into  the  receiver, 
often  becomes  cloudy  from  the  precipitation  of  the  silica  by  the  moisture 
of  the  air. 

(h.)  If  distilled  into  a  receiver  containing  water,  it  becomes  cover- 
ed with  a  siliceous  crust,  which  eventually  covers  the  water,  and  then 


*  This  may  be  presented  by  covering  them  with  a  coat  of  bees  wax,  or  probably 
copal  varnish,  but  this  last  I  have  not  tried.  It  is  said,  however,  that  dry  glass  is  not 
attacked  by  silicattd  fluoric  acid  gas. 


504  FLUO-S1LICIC  ACID. 

the  condensation  ceases;  but  if  the  receiver  be  shaken,  the  crust 
will  break  and  fall,  and  the  condensation  will  go  on  again. 

(i.)  If  the  gas  be  let  up  through  water  standing  over  mercury,  the 
silica  is  deposited  in  the  form  of  vertical  tubes. 

(j.)  When  moist  substances  are  placed  in  an  atmosphere  of  silica- 
ted  fluoric  acid  gas,  they  become  encrusted  with  it,  so  as  to  resemble 
petrifactions ;  moistened  sponge,  frogs,  lizards,  &c.  may  be  envelop- 
ed in  this  manner,  and  covered  with  a  siliceous  coat. 

(k.)  Silicated  fluoric  acid  gas  condenses  ammoniacal  gas  ;  1  vol. 
of  the  former  to  2  of  the  latter  ;  and  it  would  seem  that  the  combina- 
tion takes  place  in  no  other  proportion  ;  the  product  is  a  dry  white 
acidulous  salt,  from  which  water  precipitates  silica,  and  if  the  solution 
be  boiled  in  glass  vessels,  they  are  corroded  with  energy. — Henry. 

(I.)  By  combining  the  silicated  fluoric  acid  gas  with  liquid  ammo- 
nia, a  pure  fluate  of  ammonia  is  obtained,  while  the  silica  is  all  pre- 
cipitated. This  fluate  of  ammonia  may  then  be  decomposed  by  sul- 
phuric acid,  and  fluoric  acid  obtained  free  from  silica. 

(m.)  This  gas  unites  with  other  bases,  and  forms  compounds  that 
have  been  called,  as  Berzelius  thinks  improperly,  fluo-silicates.* 

3.  ETCHING  UPON  GLASS. 

(a.)  In  consequence  of  the  energy  with  which  fluoric  acid  acts 
upon  glass,  it  is  necessary  only  to  protect  it  where  we  would  not  choose 
to  have  it  corroded,  and  to  expose  it  in  those  places  where  we  would 
wish  an  indelible  trace. 

(b.)  Sees  wax^  forms  a  good  protection,  but  one  stilt  better  is  made 
of  this  substance  and  turpentine  melted  together  and  spread  over  the 
warm  glass,  until  an  even  coating  is  obtained  ;  a  rim  or  border  of  the 
same  substance  is  made  to  surround  the  glass,  and  then  the  pure  fluid 
acid,  diluted  to  such  a  degree  that  it  does  not  smoke,  may  be  poured  on, 
and  the  glass  should  be  carefully  turned  till  the  whole  is  thoroughly 
moistened.  Two  or  three  minutes  are  ordinarily  sufficient  to  com- 
plete the  etching,  and  the  same  portion  of  acid  will  etch  a  number  of 
plates  successively.^ 

(c.)  Those  who  have  not  a  proper  distilling  apparatus  may  effect 
the  same  object,  but  much  more  tardily  and  imperfectly,  by  allowing 
the  vapor  of  the  fluoric  acid,  as  it  rises  from  an  open  vessel  of  tin  or 
lead  to  strike  the  glass  plate,  but  there  is  danger  of  corroding  it  on 
the  wrong  side,  unless  that  too  is  protected  ;  and  also  of  melting  and 
disfiguring  the  varnish  by  the  contact  of  the  hot  acid. 

*  See  his  memoir,  Ann.  de  Chim.  et  de  Phys.  Tom.  XXVII,  and  Ann.  of  Philos. 
N.  S.  quoted  by  Henry. 

t  Isinglass  is  also  mentioned  by  Mr.  Murray,  as  a  protection,  but  this  I  have  never 
tried. 

+  Am.  Jour.  Vol.  VI,  p.  355.  I  find  this  process  easy  and  always  successful;  an 
engraver  prepares  the  plates,  and  the  etching  is  done  in  the  laboratory. 


FLUO-BORIC  ACID.  505 

(d.)  Diamonds  and  various  gems  have  been  exposed  to  the  action 
of  fluoric  acid,  but  without  much  effect.* 

FLUO-BORIC  ACID  GAS. 

1.  HISTORY. — This  singular  compound   was  obtained  about  the 
same  time  by  Gay-Lussac  and  Thenard  and  by  Sir  H.  Davy,  although 
the  former  gentlemen  first  published  their  observations.     Both  had 
the  same  object  in  view,  that  of  obtaining  fluoric  acid  gas  free  from 
water. 

2.  PROCESS. 

(a.)  A  coated  iron  tube;  vitreous  boracic  acid  1  part  and  fluor 
spar  2,  with  heat. 

(6.)  An  easier  way  is  to  distil,  in  a  glass  retort,  1  part  vitreous 
boracic  acid,  2  fluor  spar  and  12  strong  sulphuric  acid.\  Common 
crystallized  boracic  acid  answers  perfectly  well.f 

3.  PROPERTIES. 

(a.)  Colorless  and  transparent,  and,  over  mercury,  permanently 
aeriform.  It  reddens  litmus. 

(b.)  Sp.  gr.  2.36;  at  60°  Fahr.  and  30  in.  bar.  100  cubic  inches 
of  this  gas  weigh  72.044  grains. § 

(c.)  Extinguishes  flame  and  life;  very  pungent  and  suffocating, 
but  less  so  than  fluo-silicic  acid  gas. 

(d.)  The  bubbles  of  this  gas  break,  in  a  moist  air,  in  dense  white 
fumes  almost  like  snow. 

(e.)  This  arises  from  the  strong  attraction  of  the  gas  for  water, 
which  it  detects  in  almost  every  other  gas  and  precipitates  in  a  cloud, 
to  the  density  of  which  the  boracic  acid,  as  well  as  the  moisture, 
probably  contributes. 

(f.)  Water  absorbs  700  volumes  of  this  gas  and  acquires  the  sp. 
gr.  1.77;  although  it  increases  in  volume.  The  acid  thus  formed  is 
dense,  fuming  and  highly  corrosive,  and  considerably  resembles  sul- 

*  Other  stones  were  also  tried.  The  agate  lost  its  transparency  and  color ;  the 
avanturine  its  brilliant  particles,  and  appeared  like  a  gray  pebble ;  the  bloodstone 
became  soft  and  brittle,  and  its  beautiful  colors  were  changed  and  became  dull ; 
garnets  were  corroded,  and  assumed  a  dark  red  color,  and  the  gypsum  of  Mont- 
martre  and  the  sandstone  of  Fontainbleau  were  dissolved.  Rock  crystal  is  not  at- 
tacked so  readily  as  glass,  owing  to  its  stronger  aggregation.  (Gray's  Op.  Chem.  p. 
457.)  The  minerals  generally  lost  weight,  and  the  effects  may  be  referred  either  to 
the  affinity  of  the  fluoric  acid  for  silica  or  for  the  other  constituents  of  the  stones. 
Fluoric  acid  is  useful  in  giving  indelible  labels  upon  glass  for  the  laboratory ;  and 
attempts  have  been  made,  on  the  score  of  economy,  to  substitute  glass  plates,  cor- 
roded by  fluoric  acid,  instead  of  copper  plates,  and  a  funeral  piece  in  honor  of  Scheele 
was  executed  in  that  way;  but  it  is  difficult  to  sustain  the  glass  and  prevent  it  from 
cracking  in  the  press. 

t  J.  Davy,  Phil.  Trans.  1812. 

t  The  previous  vitrification  adds  considerably  to  the  trouble  of  the  experiment, 
»nd  for  a  class  experiment  presents  no  important  advantage. 

§  Thomson,  First  Prin.  Vol.  II,  p.  179. 

64 


606  FLUORIC  PRINCIPLE. 

phuric  acid.  It  requires  a  heat  above  212°  to  make  it  boil,  and  it 
condenses  again  in  striae ;  it  chars  animal  and  vegetable  substances 
like  the  sulphuric  acid;  it  blackens  paper,  and  forms  a  true  ether 
with  alcohol.  On  glass  it  has  no  effect,  its  affinity  for  silica  being  evi- 
dently supplanted  by  that  of  the  boracic  acid. 

(g.)  It  unites  with  ammoniacal  gas  in  3  proportions ;  in  equal 
measures,  if  the  ammonia  be  first  introduced  into  the  tube  ;  the  com- 
pound is  then  solid  and  neutral ;  if  the  fluo-boric  gas  pass  in  by  bub- 
bles, the  combination  is  liquid,  and  in  the  proportion  of  2  ammonia  to 
1  of  the  acid  gas.  If  to  this  last  more  fluo-boric  gas  be  admitted,  it 
is  absorbed  and  the  product  still  remains  liquid.  Heat  expels  part 
of  the  ammonia  from  both  the  fluid  compounds,  and  a  solid,  volatile 
&n4  unaltered  by  heat,  is  obtained.* 

Nature  of  the  fluoric  principles. 

1.  REMARK. — Three  acids,  the  boracic,  the  fluoric  and  the  muri- 
atic, were,  for  many  years,  mentioned  in  connexion,  as  undecomposed 
bodies.     The  boracic,   as  we  have   seen,  has  been  satisfactorily  de- 
composed,  and  the  analysis  has  been  confirmed  by  synthesis.     Its 
constitution  is  in  perfect  accordance  with  that  of  most  of  the  other 
acids,  as  it  consists  of  a  combustible  base  and  oxygen..     The  muriatic 
acid,  as  we  shall  soon  see,  is  now  regarded,  by  the  chemical  world, 
as  a  compound  of  an  inflammable  basis,  namely,  hydrogen,  not  how- 
ever with  oxygen,  but  with  chlorine,  which  is  admitted  as  a  principle 
analogous  to  oxygen,  fluoric  remains  for 

2.  COMPOSITION  OF  FLUORIC  ACID. — In  the  researches  of  Sir  H. 
Davy,  of  Gay-Lussac  andThenard,  and  of  Berzelius,  maybe  found 
most  of  the  facts  relating  to  this  investigation.     It  would  occupy  too 
much  room  to  recite  them   here  in  detail. f     Potassium  and  sodium 
can  both  be  made  to  burn  vividly  in  fluo-boric  and  fluo-silicic  acid 
gas,  and  a  combustible  substance  makes  its  appearance,  but  it  is  evi- 
dently the  basis  of  the  boracic  acid  in  the  first  case   and  of  silica  in 
the  second  j  and  accordingly,  when  they  are,  respectively,  made  to 
burn  in  oxygen  gas,  boracic  acid  and  silica  are  reproduced.     Those 
experiments  may  therefore  be  regarded   as  affording  a  convenient 
method  of  decomposing  boracic  acid   and  silica ;  and  in  that  view 
they  are  valuble,  and  the  method  by  fluo-silicic  gas  or  the  fluo-silicate 
of  soda  and  potassa  is  the  most  valuable   one  which  we  possess  for 
obtaining  the  basis  of  silica.  (See  p.  277.)     Potassium,   as  already 
stated,  burns  vividly,  and  even  with  explosion,  in  the  strongest  liquid 
fluoric  acid  that  has  hitherto  been  obtained.     As  that  fluid  is  always 


*  Henry,  Vol.  I,  p.  366. 

t  See  Recherches  Physico-Chimiques,  Tom.  II,  Phil.  Trans,  for  1813  and  1814, 

d  the  scientific  journals  of  the  day. 


FLUORIC  ACID.  507 

procured  by  the  aid  of  sulphuric  acid,*  there  would  seem  to  be  no 
reason  to  doubt  that  it  must  contain  water,f  the  decomposition  of 
which,  according  to  the  opinion  of  Gay-Lussac  and  Thenard,  affords 
the  hydrogen  which  is  evolved  and  supplies  oxygen  to  the  potassium, 
by  which  it  becomes  potassa  and  unites  with  fluoric  acid  to  form  an 
acid  fluate  of  potassa.  In  this  experiment,  therefore,  there  seems  no 
reason  to  admit  that  the  fluoric  acid  is  decomposed,  and  it  would  be 
premature  to  say  that  it  consists  of  oxygen  and  a  combustible  basis, 
although  such  a  constitution  is  certainly  both  very  possible  and  very 
probable. 

On  the  whole,  we  must,  for  the  present,  and  until  additional  re- 
searches shall  clear  up  the  difficulty,  rank  fluoric  acid  among  the  un- 
decomposed  bodies :{  although  from  analogy,  I  have  placed  it  with 
bodies  known  to  be  compound. 

EQUIVALENT  OF  FLUORIC  ACID. 

Dr.  Thomson,^*  has  concluded  that  the  representative  number  of 
fluoric  acid  is  10,  and  Berzelius  has  formed  the  same  conclusion  5 
this  is  upon  the  supposition  that  the  fluates  are  compounds  of  fluoric 


*  It  would  seem  that  the  fluoric  acid  exists  anhydrous  in  fluo-silicic  and  fluo-boric 
gas,  and  in  its  own  saline  compounds,  fluor  spar,  &c.  but  that  it  cannot  be  separated, 
in  its  pure  state,  from  its  combinations,  except  by  the  aid  of  an  acid  that  contains 
water. 

t  Especially  if  the  sulphate  of  lime  remaining  in  the  distilling  vessel  be,  as  it 
doubtless  is,  anhydrous  ;  for  besides  the  strong  affinity  of  the  fluoric  acid  for  water, 
the  residuum  in  the  vessel  is  usually  heated  to  a  degree  that  expels  all  water  from 
the  natural  hydrous  sulphates  of  lime,  and  1  have  found  it  very  hard  to  detach. 

t  Deference  to  the  opinions  of  very  able  men,  and  to  the  practice  of  some  of  the 
most  respectable  chemical  authors,  would  have  led  me  to  place  the'  hypothetical 
principle  fluorine,  in  the  text  and  in  the  tabular  arrangement.  But  it  appears  plain 
that  fluorine  would  never  have  been  thought  of,  but  for  the  supposed  analogies  with 
chlorine,  which  controverted  topic  was  keenly  agitated  about  the  time  of  the  princi- 
pal modern  researches  upon  fluoric  acid,  and  the  extension  of  these  analogies,  by  the 
discovery  of  iodine,  almost  at  the  same  period,  seemed  to  make  it,  in  a  sense,  neces- 
sary to  admit  the  existence  of  a  similar  principle  in  fluoric  acid.  These  analogies 
may  be  mentioned  again,  after  we  have  gone  through  with  the  history  of  chlorine 
and  iodine.  For  the  present,  however,  it  may  be  remarked  that  there  is  no  decisive 
experiment,  proving  the  existence  of  fluorine. 

When  Sir  H.  Davy  galvanized  the  strongest  liquid  fluoric  acid,  an  inflammable 
gas,  doubtless  hydrogen,  was  disengaged  at  the  negative  pole,  and  the  platinum  wire" 
was  rapidly  corroded  at  the  positive  ;  while  a  chocolate  colored  powder  collected 
on  the  wire.  As  it  does  not  appear  to  have  been  examined,  we  are  in  na  condition 
to  decide  whether  it  was,  as  imagined,  a  compound  of  fluorine  with  platinum,  or  an 
oxide  of  that  metal.  We  do  not  know  whether  the  solvent  powers  of  the  fluoric 
acid,  great  as  they  are,  may  not  have  been  so  exalted  by  the  galvanic  energy,  that 
this  agent  may  have  become  capable,  in  its  acid  character,  of  attacking  even  plati- 
num, while  it  would  be  even  possible  that  the  oxygen  requisite  to  oxidize  the  metal 
may  have  been  derived  from  the  water  which  would  then  give  out  the  hydrogen,  its 
other  element  at  the  negative  pole. 

To  me  it  appears  premature,  to  place  fluorine,  a  principle  purely  hypothetical,, 
along  side  with  chlorine  and  iodine,  whose  distinct  existence  and  peculiar  energy 
are  manifested  in  so  many  remarkable  forms. 

§  First  Prin.  Vol.  II. 


508  FLUATES. 

acid,  and  an  oxidated  combustible  or  metallic  base ;  if  therefore  die 
fluoric  acid  contains  one  proportion  of  oxygen  8,  the  base  will  be  ex- 
pressed by  2.* 

EQUIVALENT  OF  FLUO-SILICIC  ACID. 

Reasoning  upon  the  per  centage  of  silica  in  fluoric  acid  gas,  (61.4 
John  Davy,)  its  constitution  is  inferred  to  be, 

1  proportion  of  fluoric  acid,  =10 

1          "  silica,  16 

26,  which  would  ap- 
pear to  be  its  equivalent  number. f 

EQUIVALENT  OF  FLUO-BORIC  ACID. 

Upon  the  same  authority,  it  is  stated  at 

1  proportion  fluoric  acid,  10 

I          "         boracic  acid,  -     24 

34 

FLUATES. 

General  characters. 

Upon  the  supposition  that  they  are  compounds  of  fluoric  acid  and 
oxidated  bases,  rather  than  of  fluorine  and  bases,  or  that  they  are 
fluates  and  not  fluorides. 

1 .  Formed  synthetically,  by  the  union  of  pure  fluoric  acid  with 
the  base,  or  by  double  exchange  of  a  solution  of  an  alkaline  fluate 
with  the  intended  base  combined  with  some  acid  in  a  soluble  form. 

2.  The  neutral  fluates  with  fixed  bases,  fusible  at  high  temperatures, 
and  in  close  vessels ;  if  dry,  not  decomposed  by  any  degree  of  heat. 

3.  Fluates  of  alkalies  and  alkaline  earths  not  decomposed  by  heat, 
even  when  aided  by  the  affinity  of  combustibles. 

4.  No  anhydrous  acid  except  the  vitreous  boracic  decomposes  them 
by  heat  alone,  and  this  only  by  combining  at  the  moment  of  decom- 
position with  the  fluoric  acid. 

5.  Decomposed  by  being  moderately  heated  with  sulphuric,  muri- 
atic, phosphoric  and  arsenic  acids. 


*  If  the  fluates  are  regarded  as  fluorides,  that  is,  compounds  of  fluorine  with  a 
metal  or  combustible,  then  its  equivalent  is  obtained  by  adding  to  that  of  fluoric  acid 
the  weight  of  one  proportion  of  oxygen  supposed  to  exist  in  the  metallic  base  ;  upon 
the  supposition  that  the  salts  are  fluates,  this  will  give  10-1-8=18,  for  the  number 
representing  fluorine. 

t  Thomson's  First  Prin.  Vol.  II,  p.  176. 


FLUATES.  509 

6.  The  vapor,  which  rises,  corrodes  glass ;  this  effect  is  decisive 
as  to  the  presence  of  fluoric  acid. 

7.  Alkaline  fluates  deliquescent  and  difficult  to  crystallize. 

8.  There  are  five  native  fluates ,  namely — 

a.)  Fluor-spar  or  fluate  of  lime — the  most  important. 
b.)  The  double  fluate  of  soda  and  alumina,  called  the  cryolite, 
c.)  The  fluate  of  cerium. 

d.)  The  double  fluate  of  cerium  and  yttria,  and  what  some  choose 
to  call — 

(e.)  The  fluo-silicate  of  alumina — the  topaz. — Turner. 

FLUATE  AND  BI-FLUATE  OF  POTASSA. 

1 .  PREPARATION.  — FLUATE  . 

(a.)  Caustic  potash  and  fluor  spar  do  not  produce  this  compound 
by  heat,  but  carbonate  of  potash  and  fluor  do  by  double  exchange. 

(b.)  Water  being  added,  the  carbonate  of  lime  is  precipitated,  and 
the  fluate  ofpotassa  is  dissolved. 

(c.)  Formed  by  saturating  pure  liquid  fluoric  acid  with  potassa,* 
much  heat  is  disengaged. 

2.  PROPERTIES. 

(a.)  JL  gelatinous  deliquescent  mass,  difficult  to  crystallize — as- 
sumes a  foliated  form  if  evaporation  is  pushed  to  dryness. 

(b.)  Suffers  the  aqueous,  and  afterwards  the  igneous  fusion,  by 
heat. 

(c.)  Fluate  of  potassa  acts  upon  silica  and  glass,  especially  when 
aided  by  heat,  and  even  spontaneously  in  the  course  of  a  day  or  two, 
and  a  triple  compound  is  formed  of  earth,  acid,  and  alkali. 

(d.)   The  sulphuric  acid  expels  the  fluoric  with  brisk  effervescence. 

BI-FLUATE. 

1.  FORMATION  AND  PROPERTIES. — This  salt  is  readily  formed  by 
leaving  the  acid  in  excess,  and  is  easily  converted  into  the  neutral 
fluate  by  heating  it  to  redness,  which  expels  one  proportion  of  fluoric 
acid.     The  bi-fluate  crystallizes  in  square  tables  with  the  edges  re- 
placed ;  it  is  very  soluble  in  water. 

2.  COMPOSITION. — 1  proportion  neutral  fluate,  and  1  of  fluoric 
acid;  by  ignition,  it  leaves  74.9  of  neutral  fluate,  and  the  remainder 
is  composed  of  11.5  of  water,  13.6  acid.f 


*  Or  its  carbonate. 

t  Berzelius,  Ann.  ele  Chim.  etde  Phys.  Tom.  XX VII. 

Addition  to  fluate  of  potassa. — It  is  common  in  laboratories,  to  pass  silicated  flu- 
oric acid  gas  through  water  ;  gelatinous  silica  is  deposited,  containing  fluoric  acid, 
and  an  acid  fluate  of  silica  remains  in  the  water.  If  to  this  fluid,  caustic  potash,  or 
its  carbonate,  be  added,  there  is  formed  an  acid  fluate  of  silica  and  potassa  soluble 


510  PLUATES. 

FLUATE  OF  SODA. 

1.  PREPARATION. 

(a.)  In  the  same  manner  as  the  preceding,  and  also  by  decompos- 
ing the  acid  fluate  of  silica  by  soda.* 

(b.)  Dr.  Thomson  formed  itf  by  passing  fluo-silicic  gas,  to  satura- 
tion, through  solution  of  carbonate  of  ammonia,  which  was  then  de- 
composed by  carbonate  of  soda,  added  by  little  and  little  ;  after  evap- 
oration to  dryness  in  a  silver  vessel,  resolution  and  filtration  to  get  rid 
of  a  little  silica,  it  was  again  evaporated  and  crystallized.  The  crys- 
tals are  small  and  crackle  between  the  teeth. 

2.  PROPERTIES. 

(a.)  In  transparent  crusts  like  ice;  after  the  expulsion  of  the  water 
of  crystallization  forms  opaque  white  crusts,  becoming  again  transpa- 
rent by  immersion  in  water. 

(b.)  Not  deliquescent  or  efflorescent ;  a  little  more  soluble  in  hot 
than  in  cold  water ;  effervesces  vigorously  with  sulphuric  acid ;  taste 
bitter  and  styptic  ;  but  not  so  strong  as  the  fluate  of  potassa ;  suffers 
the  aqueous  fusion. 

FLUATE  OF  AMMONIA. J 

1.  PREPARATION. 

(a.)  Pulverized  fluor  1  part  and  sulphate  of  ammonia  2 ;  heat 
them  in  a  subliming  apparatus  ;  ammoniacal  gas  is  liberated  at  first, 
and  then  fluate  of  ammonia  sublimes  and  incrusts  the  capital. 


in  6  or  7  hundred  parts  of  water;  the  filtered  fluid,  on  evaporation,  gives  a  fluate  of 
silica  and  potassa,  gelatinous,  very  transparent,  tasteless,  without  effect  on  blue 
colors — becoming  pulverulent  with  a  mild  heat,  and  with  ignition,  exhales  silicated 
fluoric  acid  gas.  Both  the  powder  and  the  jelly  effervesce  vigorously  with  sulphuric 
acid. 

Caustic  potash,  soda  and  ammonia,  in  the  cold,  do  not  decompose  it  in  24  hours; 
potassa  and  soda  dissolve  it  with  heat. 

It  is  not  possible,  by  potash,  to  extract  pure  silica  from  silicated  fluoric  acid  gas, 
for  it  forms  with  it  an  insoluble  triple  salt.  Gay-Lussac  and  Thenard,  in  Recher.  Ph. 
Ch.  T.  II,  p.  20. 

*  The  effect  of  soda  upon  the  acid  fluate  of  silica,  is  very  different  from  that  of  po- 
tassa. There  -is  no  prompt  precipitate,  but  boiling  produces  readily  a  transparent 
jelly  of  pure  silica,  while  the  fluid  is  pure  fluate  of  soda.  In  this  manner,  pure 
silica  may  be  advantageously  prepared  even  from  the  insoluble  fluate  of  silica,  which 
is  completely  decomposed  by  soda,  with  the  same  results  as  are  obtained  from  the 
acid  fluate.— Id. 

t  First  Principles,  Vol.  II,  p.  168. 

J  Ammonia  affects  the  acid  fluate  of  silica  in  a  manner  very  different  from  potassa, 
and  even  from  soda.  It  promptly  precipitates  pure  gelatinous  silica,  opake,  and 
white,  but  a  little  silica  remains  in  solution  in  the  fluate  of  ammonia,  as  appears  from 
its  repeated  precipitation,  on  the  addition  of  pure  ammonia,  from  lime  to  time,  after 
evaporation. 

Ammonia  also  decomposes  the  solid  acid  fluate  of  silica,  as  perfectly  as  the  fluid. 

Pure  silica  then  can  be  obtained  by  ammonia,  from  either  of  them,  although  we 
cannot  in  this  way  obtain  a  pure  fluate  of  ammonia,  as  we  do  a  pure  fluate  of  soda  in 
the  parallel  process  with  that  alkali. — Id. 


FLUATES.  5J1 

(b.)  Saturate  pure  liquid  fluoric  acid  with  caustic  or  carbonated 
ammonia;  it  is  at  first  neutral,  but  by  evaporation  becomes  acid,  and 
does  not  crystallize. 

2.  PROPERTIES. — By  a  continued  heat  it  evaporates,  in  thick  white 
vapors  ;  the  taste  is  sharp, 

It  is  a  useful  fluate,  being  in  a  convenient  form  to  be  employed  as 
a  test  of  lime,  &LC. 

FLUATE  OF  BARYTA.* 

1.  PROCESS. 

(a.)  By  mingling  pure  fluoric  acid  with  barytic  water,  solid  pure 
baryta,  or  the  native  or  artificial  carbonate. 

(b.)  To  nitrate  or  muriate  of  barytes,  add  fluoric  acid,  or  any 
alkaline  fluate. 

2.  PROPERTIES. 

(a.)  A  pulverulent,  fleecy  precipitate,  sparingly  soluble  in  water, 
decomposed  by  lime  water,  and  by  sulphuric  acid. 

(b.)  Soluble  in  an  excess  of  fluoric  acid,  and  in  the  nitric  and 
muriatic  acids. 

(c.)  Sometimes  fluoric  acid  is  used  to  distinguish  between  lime 
and  baryta,  because  the  compound  with  the  latter  is  more  soluble 
than  with  the  former. 

FLUATE    OF    STRONTIA. 

Substituting  strontia  and  its  soluble  salts,  for  baryta  and  its  similar 
salts,  the  facts  with  respect  to  this  fluate  are  the  same  as  with  re- 
spect to  the  preceding,  and  their  properties  are  very  similar. 

FLUATE    OF    LIME. 

Remark. — As  ths  native  fluate  of  lime  exists  in  abundance,  there 
is  no  occasion  to  form  it  by  art. 

1.  PREPARATION. — It  may  however  be  done,  by  processes  per- 
fectly analogous  to  those  which  have  been  stated  with  respect  to 
baryta  and  strontia,  substituting  lime  water,  with  fluoric  acid,  or  bet- 
ter, the  soluble  salts  of  lime,  with  solutions  of  the  alkaline  fluates  ; 
perhaps  the  best  is  fluate  of  ammonia,  with  nitrate  of  lime ;  the  in- 
soluble precipitate  is  washed  and  dried, 

2.  PROPERTIES. 

(«.)  Lime  and  fluoric  acid  reciprocally  take  each  other  from  every 
thing  else,\  and  are  therefore  mutually  tests ;  the  soluble  alkaline 


*  If  the  acid  fluate  of  silica  be  poured  into  a  solution  of  the  muriate,  or  nitrate 
of  baryta,  in  a  few  minutes  a  multitude  of  small  crystals  are  precipitated  ;  they  are 
very  hard,  insoluble  in  water,  and  in  nitric  and  muriatic  acids,  and  suffer  no  alter- 
ation from  being  heated  with  lampblack.  There  can  be  no  doubt  that  they  are  a 
triple  compound  of  fluoric  acid,  silica,  and  baryta. 

t  Some  doubt  is  intimated  relative  to  fluate  of  magnesia. — Aikins,  Diet.  Vql.  I,  p 
441. 


512  FLUATES. 

fluates  are  generally  used   for  this  purpose,  especially  the  fluate  of 
ammonia. 

(b.)  Soluble  in  fluoric  acid,  and  in  the  nitric  and  muriatic. 

(c.)   The  native  fluate  is  phosphorescent  on  hot  iron. 

(d.)  Insipid — not  affected  by  air — at  51°  W.  fuses  into  a  trans- 
parent glass. 

(e.)  Decomposed  by  sulphuric  acid,  with  evolution  of  fluoric  acid 
gas,  as  already  stated. 

NATURAL  HISTORY. — This  belongs  to  mineralogy,  and  the  uses 
of  the  mineral  to  the  arts ;  but  it  may  be  briefly  stated  here,  that 
hitherto  only  one  mine  has  been  discovered  that  affords  the  massive 
fluor,  in  pieces  of  sufficient  size  and  firmness  to  admit  of  their  be- 
ing wrought.  This  mine  it  at  Castleton,  in  Derbyshire,  England, 
and  is  called  the  spar  rnine.J  I  saw  it  in  1805,  when  it  was  far 
from  being  exhausted. 

FLUATE  OF  MAGNESIA. 

1.  PREPARATION. 

(a.)  Carbonate  of  the  earth  and  liquid  fluoric  acid,  with  a  mild 
heat ;  there  is  effervescence  ;  near  saturation,  the  salt  falls  down 
chiefly  in  a  gelatinous  precipitate,  probably  mixed  with  silica. 

(b.)  Soluble  salts  of  magnesia,  mingled  with  liquid  fluoric  acid 
or  with  solutions  of  alkaline  fluates. 

2.  PROPERTIES. — Scarcely  soluble  in  water  ;  rather  more  so  in 
alcohol ;  not  decomposed  by  heat,  nor  by  any  acid,  but  soluble  in  the 
strong  acids. 

The  Brucite,  or  Condrodrite  contains  a  native  fluate  of  magnesia. 

FLUATE    OF    ALUMINA. 

1.  PROCESS. 

Sa.)  The  earth  precipitated  from  alum  is  soluble  in  fluoric  acid. 
b.)  Alum  and  alkaline  fluates  decompose   each  other,  and  pro- 
duce fluate  of  alumina,  and  sulphate  of  alkali. 

2.  PROPERTIES. 

(a.)  The  pulverulent  compound  becomes  gelatinous  by  evapora- 
tion, but  does  not  crystallize. 


}  In  that  mine,  it  is  not,  as  every  where  else,  mixed  with  other  spars,  and  with 
metallic  matters,  but  constitutes  entire  veins  by  itself;  these  veins  lie  imbedded  in 
solid  limestone,  and  are  wrought  for  the  sake  of  the  fluate  of  lime  only,  which  is 
manufactured  into  articles  of  furniture,  as  candle  sticks,  salt-cellars,  ink  stands,  &c., 
and  into  the  most  beautiful  ornaments  for  houses  and  palaces,  as  urns,  vases,  pyra- 
mids. 

In  this  mine,  attached  to  the  walls  and  roofs,  are  the  most  beautiful  crystallized 
incrustations,  and  regular  stalactites  of  carbonate  of  lime,  some  of  which  last  have 
reached  the  floor,  and  form  continued  pillars,  and  as  they,  and  the  incrustations  are 
generally  of  a  snowy  whiteness,  they  present  a  very  brilliant  spectacle  when  those 
dark  regions  are  lighted  up  with  candles. 


SELENIUM.  513 

(b.)  Insipid,  insoluble  in  water,  but  soluble  in  an  excess  of  acid. 

(c.)  The  compound  of  alumina,  fluoric  acid,  and  soda,  may  be 
made  to  crystallize,  and  is  even  found  native  in  the  cryolite;  and 
in  the  topaz,  fluoric  acid  is  combined  with  fluoric  acid. 

The  properties  of  thet  fluate  of  silica  have  been  incidentally  detail- 
ed, perhaps  to  a  sufficient  extent.  The  following  facts  may  how- 
ever be  advantageously  recapitulated. 

FLUATE    OF    SILICA. 

1.  This  compound  is  always  formed  when  fluoric  acid  is  obtained 
in  glass  vessels ;  more  perfectly  if  a  little  powdered  flint  or  sand  be 
mixed  with  the  materials. 

2.  Silica  is  thus  suspended  in  the  gaseous  form,  and  is  permanent 
over  quicksilver. 

3.  Water  throws  down  a  part  of  it. 

4.  Glass  vessels  are  corroded' both  by  liquid  and   gaseous  fluoric 
acid ;  Bergman  obtained  crystals  from  a  fluoric  solution,  which  Four- 
croy  regards  as  fluate  of  silica. 

5.  Alkalies  decompose  the  fluate  of  silica,  and  triple  compounds 
are  often  thus  formed. 

6.  A  similar  compound  is  formed  when  fluoric  acid  attacks  glass ; 
softer  siliceous  stones  that  contain  no  alkali,  are  attacked  by  fluoric 
acid,  with  more  difficulty. 

7.  Fluate  of  silica  is  decomposed  by  heat. 

Remarks. — It  is  very  probable  that  the  progress  of  chemical 
analysis  will  bring  to  light  more  native  combinations  ,of  earths,  with 
the  fluoric  acid ;  a  number  have  been  added  within  a  few  years. 

Gay-Lussac  and  Thenard  remark,  that  they  had  a  quantity  of 
fluor  of  the  purest  and  most  beautiful  appearance,  in  which  the  eye, 
aided  by  a  magnifier,  did  not  enable  them  to  discover  any  silex, 
which  nevertheless  yielded  silicated  fluoric  acid  gas. 

The  fluates  of  zirconia,  glucina,  and  yttria  are  formed  upon  the 
same  principles  as  the  other  earthy  fluates,  but  are  of  no  impor- 
tance.* 

SEC. — VIII. — SELENIUM. 

1.  DISCOVERY. — By  Berzelius,  in  1818.  The  iron  pyrites  of 
Fahlun,  in  Sweden,  afford  by  sublimation,  sulphur,  which  being  em- 
ployed in  the  manufacture  of  sulphuric  acid,  a  reddish  substance  f 
was  constantly  deposited  in  the  bottom  of  the  leaden  chambers.  It 
was  principally  sulphur,  but  on  burning  it,  an  odor  like  that  of  decay- 

*  See  Recher.  Phys.-Chim.  Tom.  II,  p.  27. 

t  In  this  substance,  besides  the  selenium,  Berzelius  found  mercury,  tin,  cop- 
per, zinc,  iron,  lead,  and  arsenic. 

65 


514  SELENIUM. 

ed  horse  radish  was  j>erceived,  and  on  closer  examination,  a  peculiar 
substance  was  discovered,  to  which  the  name  of  selenium  was  given. 
It  has  been  discovered  in  the  form  of  sulphuret  of  selenium,  among 
the  volcanic  products  of  the  Lipari  islands ;  at  Clausthal,  in  the 
Hartz  mountains,  in  combination  with  lead,  cobalt,  silver,  mercury 
and  copper  ;  in  several  varieties  of  sulphur,  in  the  sulphuric  acid  of 
Nordhausen,  and  in  that  manufactured  from  the  sulphur  of  pyrites, 
from  the  isle  of  Anglesea. 

2.  NAME. — From  2eX>jvif],    the  moon,  in   analogy  with  tellurium, 
from  tellus ;  the  substance  having  some  resemblance  to  tellurium, 
and  having  at  first  been  mistaken  for  it  by  Berzelius.* 

3.  PROCESS. — The  process  of  Berzelius  being  very  long,  the 
shorter  one  of  Lewenau  is  here  abridged. 

The  red  deposit  1  Ib.  is  placed  in  a  2  quart  tubulated  retort, 
whose  sides  must  not  be  soiled ;  it  is  placed  in  the  sand  bath,  and 
connected  with  a  large  globular  receiver,  joined  by  a  Woulfe's  tube, 
to  a  flask  full  of  water,  and  all  properly  luted. 

Nitro  muriatic  acid,  composed  of  8  muriatic,  sp.  gr.  1.2,  to  4  of 
nitric,  sp.  gr.  1.5,j*  was  now  introduced  by  portions,  to  the  bottom 
of  the  retort,  intervals  being  allowed  for  the  subsidence  of  the  effer- 
vescence, and  of  the  heat. 

Red  vapors  escaped,  the  liquid  in  the  retort  became  dark  gray, 
and  that  in  the  Woulfe's  bottle,  reddish  yellow. 

The  fluid  being  distilled  over  in  the  retort,  a  reddish  yellow  gas 
was  disengaged,  and  near  the  end,  small  yellow  stellated  crystals 
lined  the  neck  of  the  retort,  which  disappeared  with  the  increase  of 
the  heat ;  most  of  the  liquid  having  thus  passed,  more  acid  was  ad- 
ded in  portions,  and  a  violent  action  ensued  at  every  addition,  the 
water  in  the  flask  being  several  times  changed,  as  it  became  satura- 
ted with  the  acid  vapors.  All  the  liquors  being  redistilled  from 
the  retort,  an  insoluble  residuum,  of  a  deep  red  color,  supposed  to 
be  selenium,  now  occupied  its  bottom  and  sides.  To  dissolve  it, 
l£  Ibs.  of  fuming  nitric  acid  was  next  added,  and  distilled  nearly  to 
dryness.  The  residuum  was  then  washed  with  boiling  distilled 
water,  till  it  came  off  tasteless,  and  the  filtered  fluid  was  of  a  light 
yellow.  J  This  fluid  contained  the  selenium  in  the  form  of  selenic 
acid,  and  to  precipitate  it,  (neglecting  the  metals  that  might  be  in  so- 
lution,) recently  prepared  sulphite  of  ammonia,  in  large  excess,  was 
added,  which  threw  down  the  selenium  in  the  form  of  large  cinnabar 


*  See  Ann.  de  Chim.  et  de  Phys.  Vol.  IX,  and  Ann.  Phil.  Vol.  VIII,  N.  S.  and 
Vol.  XIII. 

t  The  author  speaks  of  12  Ibs.  of  the  mixed  acid,  but  this  seem?  disproportioned 
Jo  the  size  of  the  retort. 

J  The  distilled  fluid  was  found  to  be  slightly  seleniferous. 


OXIDE  OF  SELENIUM.  515 

colored  flakes.  When  the  solution  was  strong,  the  precipitation  was 
immediate ;  if  dilute,  it  was  more  tardy,  and  the  color  varied  from 
bright  red  to  dark  gray.  The  selenium  was  washed  with  5  or  6 
parts  of  cold  distilled  water,  till  muriate  of  baryta  gave  no  precipitate, 
and  lastly,  it  was  dried  in  the  shade. 

The  selenium  still  contained  in  the  liquor  is  obtained  by  concen- 
tration, by  evaporating  to  two  thirds  the  bulk,  and  the  addition  of 
more  sulphite  of  ammonia,  and  finally  by  immersing  bars  of  zinc, 
taking  care  that  these  do  not  remain  in  too  long,  and  thus  mix  their 
own  substance  with  the  selenium.* 

4.  PROPERTIES. 

(a.)  Color  various  ;  if  rapidly  cooled,  dark  brown,  or  gray,  or  of 
a  leaden  color,  and  metallic  lustre,  it  often  resembles  polished  he- 
matite ;  when  in  powder  of  a  deep  red,  adheres  by  pounding,  and  its 
surface  gray  and  smooth. 

(b.)  It  is  not  hard,  but  it  is  brittle;  fracture  conchoidal,  of  the 
color  of  lead,  and  perfectly  metallic;  lustre  vitreous. 

(c.)  Sp.  gr.  between  4.31,  and  4.32. 

(d.)  Jit  212°  soft  and  ductile,  like  Spanish  wax,  and  may  be 
kneaded  between  the  fingers,  or  drawn  into  fine  translucent  threads, 
wiiich  have  a  metallic  aspect ;  "  red  by  transmitted,  but  gray  by 
reflected  light."  Becomes  quite  fluid,  at  a  temperature  considera- 
bly above  that  of  boiling  water,  and  near  that  of  boiling  mercury,  or 
about  650°,  it  boils,  and  may  be  distilled  in  a  retort,  condensing  like 
mercury,  in  metallic  drops,  or  if  a  retort  with  a  large  neck  is  used, 
or  sufficient  space  to  mix  it  with  cold  air,  in  a  light  sublimate,  of  a 
fine  cinnabar  color.  Its  vapor  is  of  a  color  between  that  of  chlorine, 
and  that  of  the  vapor  of  sulphur.  If  cooled  slowly,  it  assumes  a 
granulated  fracture,  like  that  of  cobalt. 

(e.)  At  the  boiling  point  its  vapor  is  inodorous ;  but  under  the 
blowpipe  a  piece  not  over  j\  of  a  gr.  will  Jill  a  large  room  with  the 
smell  of  horse  radish :  it  tinges  the  blowpipe  flame  of  a  fine  azure 
blue. 

(/.)  Insoluble  in  water  ;  not  altered  by  the  air. 

(g.)  A  non-conductor  of  heat  and  electricity,  and  does  not  become 
electric  by  friction. 

OXIDE  OF  SELENIUM. 

(a.)  The  peculiar  odor  is  developed  when  the  exterior  flame  of 
the  blowpipe  is  applied,  and  is  caused  by  the  combination  of  selenium 


*  The  sulphureous  deposit  examined  by  Mr.  Lewenau  was  from  ^  sulphuric  acid 
manufactory,  in  Hungary :  it  was  much  richer  than  that  of  Sweden,  and  afforded 
591.82  grs.  to  the  pound  of  the  crude  substance,  of  which  484.16  was  from  the  first 
precipitate.— Ann.  Phil.  N.  S.  Vol.  VIII,  p.  106.  In  one  instance,  the  material  of 
Sweden  gave  Berzelius  only  0.0015  of  its  weight. 


516  SELENIOUS  ACID. 

with  oxygen,  forming  a  gaseous  oxide  of  selenium*  and  like  arsenic 
it  is  odorous  only  while  combining  with  oxygen  at  a  high  temperature. 

(b.)  Formed  best  by  heating  selenium  in  a  close  glass  vessel,  with  a 
limited  quantity  of  air,  which  is  to  be  washed  to  remove  the  selenic 
acid,  a  little  of  which  is  formed  at  the  same  time  ;  the  water  acquires 
the  smell  of  the  gas,  and  feebly  reddens  litmus. 

The  oxide  of  selenium  is  only  sparingly  soluble  in  water,  and  does 
not  combine  with  alkalies.  Its  composition  has  not  been  ascertained, 
but  it  is  supposed  to  be  one  proportion  of  each  of  the  constituents. 

SELENIOUS  ACID. 

1.  PROPERTIES. 

(a.)  Selenium  is  combustible.  Heated  in  a  flask  filled  with  oxy- 
gen gas,  selenium  evaporates  with  the  odor  of  oxide  of  selenium,,  but 
without  inflaming,  and  exactly  as  it  would  do  in  common  air ;  but 
if  heated  in  a  glass  ball  of  an  inch  in  diameter,  and  supplied  with 
oxygen  gas  at  the  moment  of  ebullition,  it  burns  with  a  feeble  flame, 
white  towards  the  base,  and  green,  or  bluish  green  on  the  edges  :  the 
selenium  is  completely  consumed,  oxygen  gas  is  absorbed,  and  the 
remaining  ga§  has  the  odor  of  oxide  of  selenium.  The  product  is  a 
sublimate  of  selenious  acid. 

(b.)  Hot  nitric  acid  dissolves  selenium,  and  forms  on  cooling  large 
prismatic  crystals  of  selenic  acid,  longitudinally  striated,  and  resem- 
bling almost  exactly  those  of  nitrate  of  potash. 

(c.)  This  acid  is  still  better  prepared  by  the  aid  of  nitro-muriatic 
acid.  A  white  residuum  is  left  on  evaporation,  and  by  an  increased 
heat  the  selenious  acid  sublimes,  and  is  condensed  in  the  colder  part 
of  the  apparatus  in  very  longf  needles  of  four  sides.  The  vapor  of 
the  acid  has  a  deep  yellow  color  much  resembling  that  of  chlorine, 
but  not  so  deep  as  that  of  the  vapor  of  the  selenium  itself. 

(d.)  Selenious  acid  has  a  peculiar  lustre  which  it  quickly  loses  on 
being  exposed  to  the  air  ;  the  crystals  adhere  and  it  gains  weight  so 
fast  that  it  is  difficult  to  weigh  it  accurately.  Taste  acid,  leaving  a 
slightly  burning  sensation. 

(e.)  Readily  soluble  in  cold  and  almost  without  limit  in  hot  water, 
from  which,  by  rapid  cooling,  it  crystallizes  in  grains,  and  more  slow- 
ly in  prisms,  and  spontaneously  in  acicular  radiated  groups.  Very 
soluble  in  alcohol  and  giving  with  that  fluid  by  distillation  an  etherial 
odor,  intermediate  between  that  of  nitre  and  sulphuric  ether. 

(f.)  Sulphuric  acid,  selenic  acid,  and  alcohol  in  mixture  produce 
by  distillation,  a  most  insupportable  odor.  Decomposition.  Easily  af- 


*  Which  Berzelius  thinks  analogous  to  the  oxide  of  carbon,  although  ho  has  not 
been  able  to  isolate  and  shew  it  separately. 

t  In  a  large  retort  they  are  sometimes  two  inches  or  more  long. 


SELENIC  ACID.  517 

fected  by  all  bodies  having  a  strong  affinity  for  oxygen,  as  sulphurous 
and  phosphorous  acids,  alkaline  sulphites,  and  sulphuretted  hydrogen, 
and  metallic  zinc,*  by  all  of  which  it  is  precipitated.  Zinc  throws 
it  down  in  the  form  of  red,  brown,  or  blackish  flakes  :  sulphuretted 
hydrogen  in  an  orange  precipitate,  fusible  a  little  above  212°,  sub- 
limed in  close  vessels,  burning  in  the  air  and  producing  selenic  and 
sulphurous  acids. 

(g.)  Selenium  is  soluble  in  oils;  it  unites  with  the  metals  usually  with 
ignition,  forming  seleniurets  commonly  of  a  gray  color  and  metallic 
lustre.  The  seleniuret  of  potassium  is  soluble  in  water  with  efferves- 
cence. The  acids  disengage  from  it  seleniuretted  hydrogen,  whose 
odor  is  like  that  of  sulphuretted  hydrogen  but  excessively  offensive. 

This  gas  is  soluble  in  water,  combines  with  the  alkalies,  and  pre- 
cipitates metallic  salts  of  a  dark  color. 

2.  EQUIVALENT  NUMBER. — Berzelius  from  his  investigations  con- 
cludes that  selenious  acid  consists  of 

Selenium,  71.261  100.00 

Oxygen,  28.739  40.33 

If  it  is  composed  of  one  proportion  of  base  and  two  of  oxygen,  the 
equivalent  number  of  selenium  will  be  40+2  oxygen  16=56ybr  tht 
equivalent  of  selenic  acid. 

SELENIC  ACID. 

The  acid  just  described  has  been  hitherto  called  by  this  name,  but 
another  acid  has  been  discovered  containing  an  additional  equivalent 
of  oxygen,  and  which  is  therefore  called  selenic  acid. 

1.  PREPARATION. — Omitting  the  tedious  process  upon  the  selenitic 
ores,f  we  may  describe  that  which  commences  with  the  preceding 
acid,  the  selenious. 

(a.)  It  is  neutralized  by  soda,  and  by  fusion  with  nitre  or  with  ni- 
trate of  soda  it  is  converted  into  seleniate  of  soda  and  crystallized. 

(b.)  This  seleniate  is  decomposed  by  nitrate  of  lead,  which  gives 
an  insoluble  seleniate. 

(c.)  This  is  decomposed  by  a  stream  of  sulphuretted  hydrogen, 
which  precipitates  the  lead  as  a  sulphuret  and  liberates,  without  de- 
composing the  selenic  acid  ;  the  excess  of  sulphuretted  hydrogen  be- 
ing expelled  by  heat,  the  selenic  acid  remains  diluted  with  water. 

2.  PROPERTIES. 

(a.)  Colorless;  not  decomposed  below  576°  Fahr.  but  above  that 
emits  oxygen  and  becomes  selenious  acid. 

(b.)  Sp.  gr. — When  concentrated  at  329°,  it  is  2.524 ;  if  at  512°, 
it  is  2.60 ;  and  if  at  545°,  it  is  2.625  ;  but  a  little  selenious  acid  is 


Mixed  with  muriatic  acid. 

Edin.  Jour,  of  Science,  No.  XVI,  p.  294,  and  Turner,  2d  ed.  p.  350. 


518  SELENIUM. 

then  present.  Concentrated  at  a  heat  above  576°,  and  deducting 
the  selenious  acid  present,  it  appeared  to  contain  15.75  water. 

(c.)  Attracts  water  powerfully,  and  by  combining  with  it,  evolves 
as  much  heat  as  sulphuric  acid. 

(d.)  Boiled  with  muriatic  acid,  selenious  acid  is  deposited  and 
chlorine  liberated,  and  the  solution  dissolves  gold  but  not  platinum ; 
it  resembles  aqua  regia,  and  probably  contains  it. 

It  unites  with  alkaline  bases  and  forms  salts,  which  are  with  diffi- 
culty decomposed  by  sulphuric  acid,  which  it  appears  strongly  to  re- 
semble. 

(jf.)  Selenic  acid  dissolves  iron  and  zinc,  with  disengagement  of 
hydrogen  gas. 

3.  ITS  EQUIVALENT. — It  appears  to  contain  3  equivalents  of  oxy- 
gen, 24-f-l  of  selenium,  40  =  64. 

CLASSIFICATION. — Selenium  resembles  the  metals  in  sp.  gr.,  and 
metallic  lustre,  and  in  most  of  its  chemical  properties,  but  it  is  a  non- 
conductor of  heat  and  electricity.  Berzelius  ranked  it  with  the  met- 
als, and  it  has  a  considerable  resemblance  to  tellurium,  but  it  is  rather 
more  like  sulphur,  and  on  the  whole  seems  to  form  a  connecting  link 
between  the  combustibles  and  the  metals.  Its  combination  with  hy- 
drogen appears  to  be  particularly  noxious,  and  it  is  probable  that  it 
often  renders  sulphuretted  hydrogen  more  noxious,  since  there  is  reason 
to  believe  that  it  is  not  unfrequently  present  i«*that  gas,  as  sulphur  is 
often  contaminated  by  it.  It  is  obtained  by  heating  the  seleniuret  of 
iron  with  muriatic  acid,  by  an  obvious  theory.  The  gas  is  acid  and 
has  been  called  hydro-selenic  acid  and  seleniuretted  hydrogen.  It  is 
colorless,  fetid,  irritates  and  paralyses  the  membrane  of  the  nose  for 
some  hours,  so  that  the  sense  of  smell  is  destroyed  ;  it  is  dissolved  by 
water  and  stains  the  skin  brown.  It  is  decomposed  by  the  air  and 
leaves  selenium.  With  all  the  metallic  solutions  it  forms  seleniurets.* 

Selenium  being  as  yet  a  substance  very  difficult  to  be  obtained,  we 
must  refer,  for  numerous  additional  particulars  and  for  the  history  of 
the  seleniates,,  to  the  elaborate  mempir  of  Berzelius,  in  the  ninth  vol- 
ume of  the  Annales  de  Chimie  et  de  Physique. 


*  Turner,  2d  ed.  p.  356. 


END  OF  VOL.  1. 


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